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authorChris Johns <chrisj@rtems.org>2016-10-07 11:13:16 +1300
committerChris Johns <chrisj@rtems.org>2016-10-07 11:13:16 +1300
commitf233256327e8a01a1236dbdd0f91701bc229936b (patch)
tree418c22a848fda4c88cbe08404a76b7a36b3cd3d3 /cpu_supplement
parente6fe68d51d51bebecb645369f7e0beec6b694a9a (diff)
downloadrtems-docs-f233256327e8a01a1236dbdd0f91701bc229936b.tar.bz2
Clean up the CPU Supplement.
Diffstat (limited to '')
-rw-r--r--cpu_supplement/altera_nios_ii.rst8
-rw-r--r--cpu_supplement/arm.rst100
-rw-r--r--cpu_supplement/atmel_avr.rst100
-rw-r--r--cpu_supplement/blackfin.rst120
-rw-r--r--cpu_supplement/ephiphany.rst45
-rw-r--r--cpu_supplement/index.rst59
-rw-r--r--cpu_supplement/intel_amd_x86.rst340
-rw-r--r--cpu_supplement/lattice_micro32.rst168
-rw-r--r--cpu_supplement/m68xxx_and_coldfire.rst362
-rw-r--r--cpu_supplement/mips.rst74
-rw-r--r--cpu_supplement/openrisc_1000.rst37
-rw-r--r--cpu_supplement/port.rst498
-rw-r--r--cpu_supplement/powerpc.rst556
-rw-r--r--cpu_supplement/preface.rst90
-rw-r--r--cpu_supplement/renesas_m32c.rst11
-rw-r--r--cpu_supplement/sparc.rst1111
-rw-r--r--cpu_supplement/sparc64.rst625
-rw-r--r--cpu_supplement/superh.rst90
-rw-r--r--cpu_supplement/xilinx_microblaze.rst11
19 files changed, 1985 insertions, 2420 deletions
diff --git a/cpu_supplement/altera_nios_ii.rst b/cpu_supplement/altera_nios_ii.rst
index e1e3c43..f0f994b 100644
--- a/cpu_supplement/altera_nios_ii.rst
+++ b/cpu_supplement/altera_nios_ii.rst
@@ -1,5 +1,8 @@
.. comment SPDX-License-Identifier: CC-BY-SA-4.0
+.. COMMENT: COPYRIGHT (c) 2014 Hesham ALMatary <heshamelmatary@gmail.com>
+.. COMMENT: All rights reserved.
+
Altera Nios II Specific Information
###################################
@@ -12,8 +15,3 @@ Thread-Local Storage
====================
Thread-local storage is not implemented.
-
-.. COMMENT: COPYRIGHT (c) 2014 Hesham ALMatary <heshamelmatary@gmail.com>
-
-.. COMMENT: All rights reserved.
-
diff --git a/cpu_supplement/arm.rst b/cpu_supplement/arm.rst
index 05dda39..64fc156 100644
--- a/cpu_supplement/arm.rst
+++ b/cpu_supplement/arm.rst
@@ -1,31 +1,37 @@
.. comment SPDX-License-Identifier: CC-BY-SA-4.0
+.. COMMENT: COPYRIGHT (c) 1988-2009.
+.. COMMENT: On-Line Applications Research Corporation (OAR).
+.. COMMENT: All rights reserved.
+
ARM Specific Information
########################
-This chapter discusses the`ARM architecture <http://en.wikipedia.org/wiki/ARM_architecture>`_
-dependencies in this port of RTEMS. The ARMv4T (and compatible), ARMv7-A,
-ARMv7-R and ARMv7-M architecture versions are supported by RTEMS. Processors
-with a MMU use a static configuration which is set up during system start. SMP
-is supported.
+This chapter discusses the *ARM architecture*
+(http://en.wikipedia.org/wiki/ARM_architecture) dependencies in this port of
+RTEMS. The ARMv4T (and compatible), ARMv7-A, ARMv7-R and ARMv7-M architecture
+versions are supported by RTEMS. Processors with a MMU use a static
+configuration which is set up during system start. SMP is supported.
**Architecture Documents**
-For information on the ARM architecture refer to the`ARM Infocenter <http://infocenter.arm.com>`_.
+For information on the ARM architecture refer to the *ARM Infocenter*
+(http://infocenter.arm.com/).
CPU Model Dependent Features
============================
-This section presents the set of features which vary
-across ARM implementations and are of importance to RTEMS. The set of CPU
-model feature macros are defined in the file:file:`cpukit/score/cpu/arm/rtems/score/arm.h` based upon the particular CPU
-model flags specified on the compilation command line.
+This section presents the set of features which vary across ARM implementations
+and are of importance to RTEMS. The set of CPU model feature macros are
+defined in the file :file:`cpukit/score/cpu/arm/rtems/score/arm.h` based upon
+the particular CPU model flags specified on the compilation command line.
CPU Model Name
--------------
-The macro ``CPU_MODEL_NAME`` is a string which designates
-the architectural level of this CPU model. See in:file:`cpukit/score/cpu/arm/rtems/score/arm.h` for the values.
+The macro ``CPU_MODEL_NAME`` is a string which designates the architectural
+level of this CPU model. See in :file:`cpukit/score/cpu/arm/rtems/score/arm.h`
+for the values.
Count Leading Zeroes Instruction
--------------------------------
@@ -51,32 +57,32 @@ Multilibs
The following multilibs are available:
-# ``.``: ARMv4T, ARM instruction set
+#. ``.``: ARMv4T, ARM instruction set
-# ``thumb``: ARMv4T, Thumb-1 instruction set
+#. ``thumb``: ARMv4T, Thumb-1 instruction set
-# ``thumb/armv6-m``: ARMv6M, subset of Thumb-2 instruction set
+#. ``thumb/armv6-m``: ARMv6M, subset of Thumb-2 instruction set
-# ``thumb/armv7-a``: ARMv7-A, Thumb-2 instruction set
+#. ``thumb/armv7-a``: ARMv7-A, Thumb-2 instruction set
-# ``thumb/armv7-a/neon/hard``: ARMv7-A, Thumb-2 instruction set with
- hard-float ABI Neon and VFP-D32 support
+#. ``thumb/armv7-a/neon/hard``: ARMv7-A, Thumb-2 instruction set with
+ hard-float ABI Neon and VFP-D32 support
-# ``thumb/armv7-r``: ARMv7-R, Thumb-2 instruction set
+#. ``thumb/armv7-r``: ARMv7-R, Thumb-2 instruction set
-# ``thumb/armv7-r/vfpv3-d16/hard``: ARMv7-R, Thumb-2 instruction set
- with hard-float ABI VFP-D16 support
+#. ``thumb/armv7-r/vfpv3-d16/hard``: ARMv7-R, Thumb-2 instruction set with
+ hard-float ABI VFP-D16 support
-# ``thumb/armv7-m``: ARMv7-M, Thumb-2 instruction set with hardware
- integer division (SDIV/UDIV)
+#. ``thumb/armv7-m``: ARMv7-M, Thumb-2 instruction set with hardware
+ integer division (SDIV/UDIV)
-# ``thumb/armv7-m/fpv4-sp-d16``: ARMv7-M, Thumb-2 instruction set with
- hardware integer division (SDIV/UDIV) and hard-float ABI FPv4-SP support
+#. ``thumb/armv7-m/fpv4-sp-d16``: ARMv7-M, Thumb-2 instruction set with
+ hardware integer division (SDIV/UDIV) and hard-float ABI FPv4-SP support
-# ``eb/thumb/armv7-r``: ARMv7-R, Big-endian Thumb-2 instruction set
+#. ``eb/thumb/armv7-r``: ARMv7-R, Big-endian Thumb-2 instruction set
-# ``eb/thumb/armv7-r/vfpv3-d16/hard``: ARMv7-R, Big-endian Thumb-2
- instruction set with hard-float ABI VFP-D16 support
+#. ``eb/thumb/armv7-r/vfpv3-d16/hard``: ARMv7-R, Big-endian Thumb-2 instruction
+ set with hard-float ABI VFP-D16 support
Multilib 1. and 2. support the standard ARM7TDMI and ARM926EJ-S targets.
@@ -93,15 +99,17 @@ Multilib 4. and 5. support the Cortex-A processors.
Multilib 6., 7., 10. and 11. support the Cortex-R processors. Here also
big-endian variants are available.
-Use for example the following GCC options
-.. code:: c
+Use for example the following GCC options:
+
+.. code-block:: shell
-mthumb -march=armv7-a -mfpu=neon -mfloat-abi=hard -mtune=cortex-a9
to build an application or BSP for the ARMv7-A architecture and tune the code
for a Cortex-A9 processor. It is important to select the options used for the
-multilibs. For example
-.. code:: c
+multilibs. For example:
+
+.. code-block:: shell
-mthumb -mcpu=cortex-a9
@@ -110,7 +118,8 @@ alone will not select the ARMv7-A multilib.
Calling Conventions
===================
-Please refer to the`Procedure Call Standard for the ARM Architecture <http://infocenter.arm.com/help/topic/com.arm.doc.ihi0042c/IHI0042C_aapcs.pdf>`_.
+Please refer to the *Procedure Call Standard for the ARM Architecture*
+(http://infocenter.arm.com/help/topic/com.arm.doc.ihi0042c/IHI0042C_aapcs.pdf).
Memory Model
============
@@ -143,13 +152,13 @@ operating system support for the FIQ it is not necessary to disable them during
critical sections of the system.
The ARMv7-M architecture has a completely different exception model. Here
-interrupts are disabled with a write of 0x80 to the ``basepri_max``
-register. This means that all exceptions and interrupts with a priority value
-of greater than or equal to 0x80 are disabled. Thus exceptions and interrupts
-with a priority value of less than 0x80 are non-maskable with respect to the
-operating system and therefore must not use operating system services. Several
-support libraries of chip vendors implicitly shift the priority value somehow
-before the value is written to the NVIC IPR register. This can easily lead to
+interrupts are disabled with a write of 0x80 to the ``basepri_max`` register.
+This means that all exceptions and interrupts with a priority value of greater
+than or equal to 0x80 are disabled. Thus exceptions and interrupts with a
+priority value of less than 0x80 are non-maskable with respect to the operating
+system and therefore must not use operating system services. Several support
+libraries of chip vendors implicitly shift the priority value somehow before
+the value is written to the NVIC IPR register. This can easily lead to
confusion.
Interrupt Levels
@@ -168,8 +177,8 @@ the stacks is usually reserved in the linker script.
Default Fatal Error Processing
==============================
-The default fatal error handler for this architecture performs the
-following actions:
+The default fatal error handler for this architecture performs the following
+actions:
- disables operating system supported interrupts (IRQ),
@@ -187,10 +196,3 @@ Thread-Local Storage
====================
Thread-local storage is supported.
-
-.. COMMENT: COPYRIGHT (c) 1988-2009.
-
-.. COMMENT: On-Line Applications Research Corporation (OAR).
-
-.. COMMENT: All rights reserved.
-
diff --git a/cpu_supplement/atmel_avr.rst b/cpu_supplement/atmel_avr.rst
index 21e2a0b..6a3ce02 100644
--- a/cpu_supplement/atmel_avr.rst
+++ b/cpu_supplement/atmel_avr.rst
@@ -1,15 +1,18 @@
.. comment SPDX-License-Identifier: CC-BY-SA-4.0
+.. COMMENT: COPYRIGHT (c) 1988-2006.
+.. COMMENT: On-Line Applications Research Corporation (OAR).
+.. COMMENT: All rights reserved.
+
Atmel AVR Specific Information
##############################
-This chapter discusses the AVR architecture dependencies in this
-port of RTEMS.
+This chapter discusses the AVR architecture dependencies in this port of RTEMS.
**Architecture Documents**
-For information on the AVR architecture, refer to the following
-documents available from Atmel.
+For information on the AVR architecture, refer to the following documents
+available from Atmel.
TBD
@@ -18,15 +21,15 @@ TBD
CPU Model Dependent Features
============================
-CPUs of the AVR 53X only differ in the peripherals and thus in the
-device drivers. This port does not yet support the 56X dual core variants.
+CPUs of the AVR 53X only differ in the peripherals and thus in the device
+drivers. This port does not yet support the 56X dual core variants.
Count Leading Zeroes Instruction
--------------------------------
-The AVR CPU has the XXX instruction which could be used to speed
-up the find first bit operation. The use of this instruction should
-significantly speed up the scheduling associated with a thread blocking.
+The AVR CPU has the XXX instruction which could be used to speed up the find
+first bit operation. The use of this instruction should significantly speed up
+the scheduling associated with a thread blocking.
Calling Conventions
===================
@@ -34,56 +37,51 @@ Calling Conventions
Processor Background
--------------------
-The AVR architecture supports a simple call and return mechanism.
-A subroutine is invoked via the call (``call``) instruction.
-This instruction saves the return address in the ``RETS`` register
-and transfers the execution to the given address.
+The AVR architecture supports a simple call and return mechanism. A subroutine
+is invoked via the call (``call``) instruction. This instruction saves the
+return address in the ``RETS`` register and transfers the execution to the
+given address.
-It is the called funcions responsability to use the link instruction
-to reserve space on the stack for the local variables. Returning from
-a subroutine is done by using the RTS (``RTS``) instruction which
-loads the PC with the adress stored in RETS.
+It is the called funcions responsability to use the link instruction to reserve
+space on the stack for the local variables. Returning from a subroutine is
+done by using the RTS (``RTS``) instruction which loads the PC with the adress
+stored in RETS.
-It is is important to note that the ``call`` instruction does not
-automatically save or restore any registers. It is the responsibility
-of the high-level language compiler to define the register preservation
-and usage convention.
+It is is important to note that the ``call`` instruction does not automatically
+save or restore any registers. It is the responsibility of the high-level
+language compiler to define the register preservation and usage convention.
Register Usage
--------------
-A called function may clobber all registers, except RETS, R4-R7, P3-P5,
-FP and SP. It may also modify the first 12 bytes in the caller's stack
-frame which is used as an argument area for the first three arguments
-(which are passed in R0...R3 but may be placed on the stack by the
-called function).
+A called function may clobber all registers, except RETS, R4-R7, P3-P5, FP and
+SP. It may also modify the first 12 bytes in the caller's stack frame which is
+used as an argument area for the first three arguments (which are passed in
+R0...R3 but may be placed on the stack by the called function).
Parameter Passing
-----------------
-RTEMS assumes that the AVR GCC calling convention is followed.
-The first three parameters are stored in registers R0, R1, and R2.
-All other parameters are put pushed on the stack. The result is returned
-through register R0.
+RTEMS assumes that the AVR GCC calling convention is followed. The first three
+parameters are stored in registers R0, R1, and R2. All other parameters are
+put pushed on the stack. The result is returned through register R0.
Memory Model
============
-The AVR family architecutre support a single unified 4 GB byte
-address space using 32-bit addresses. It maps all resources like internal
-and external memory and IO registers into separate sections of this
-common address space.
+The AVR family architecutre support a single unified 4 GB byte address space
+using 32-bit addresses. It maps all resources like internal and external memory
+and IO registers into separate sections of this common address space.
-The AVR architcture supports some form of memory
-protection via its Memory Management Unit. Since the
-AVR port runs in supervisior mode this memory
+The AVR architcture supports some form of memory protection via its Memory
+Management Unit. Since the AVR port runs in supervisior mode this memory
protection mechanisms are not used.
Interrupt Processing
====================
-Discussed in this chapter are the AVR's interrupt response and
-control mechanisms as they pertain to RTEMS.
+Discussed in this chapter are the AVR's interrupt response and control
+mechanisms as they pertain to RTEMS.
Vectoring of an Interrupt Handler
---------------------------------
@@ -93,19 +91,18 @@ TBD
Disabling of Interrupts by RTEMS
--------------------------------
-During interrupt disable critical sections, RTEMS disables interrupts to
-level N (N) before the execution of this section and restores them
-to the previous level upon completion of the section. RTEMS uses the
-instructions CLI and STI to enable and disable Interrupts. Emulation,
-Reset, NMI and Exception Interrupts are never disabled.
+During interrupt disable critical sections, RTEMS disables interrupts to level
+N (N) before the execution of this section and restores them to the previous
+level upon completion of the section. RTEMS uses the instructions CLI and STI
+to enable and disable Interrupts. Emulation, Reset, NMI and Exception
+Interrupts are never disabled.
Interrupt Stack
---------------
-The AVR Architecture works with two different kind of stacks,
-User and Supervisor Stack. Since RTEMS and its Application run
-in supervisor mode, all interrupts will use the interrupted
-tasks stack for execution.
+The AVR Architecture works with two different kind of stacks, User and
+Supervisor Stack. Since RTEMS and its Application run in supervisor mode, all
+interrupts will use the interrupted tasks stack for execution.
Default Fatal Error Processing
==============================
@@ -137,10 +134,3 @@ System Reset
------------
TBD
-
-.. COMMENT: COPYRIGHT (c) 1988-2006.
-
-.. COMMENT: On-Line Applications Research Corporation (OAR).
-
-.. COMMENT: All rights reserved.
-
diff --git a/cpu_supplement/blackfin.rst b/cpu_supplement/blackfin.rst
index 41dc970..e26ceb8 100644
--- a/cpu_supplement/blackfin.rst
+++ b/cpu_supplement/blackfin.rst
@@ -1,124 +1,119 @@
.. comment SPDX-License-Identifier: CC-BY-SA-4.0
+.. COMMENT: Copyright (c) 2015 University of York.
+.. COMMENT: Hesham ALMatary <hmka501@york.ac.uk>
+
Blackfin Specific Information
#############################
-This chapter discusses the Blackfin architecture dependencies in this
-port of RTEMS.
+This chapter discusses the Blackfin architecture dependencies in this port of
+RTEMS.
**Architecture Documents**
-For information on the Blackfin architecture, refer to the following
-documents available from Analog Devices.
+For information on the Blackfin architecture, refer to the following documents
+available from Analog Devices.
TBD
-- *"ADSP-BF533 Blackfin Processor Hardware Reference."*:file:`http://www.analog.com/UploadedFiles/Associated_Docs/892485982bf533_hwr.pdf`
+- *"ADSP-BF533 Blackfin Processor Hardware Reference."* http://www.analog.com/UploadedFiles/Associated_Docs/892485982bf533_hwr.pdf
CPU Model Dependent Features
============================
-CPUs of the Blackfin 53X only differ in the peripherals and thus in the
-device drivers. This port does not yet support the 56X dual core variants.
+CPUs of the Blackfin 53X only differ in the peripherals and thus in the device
+drivers. This port does not yet support the 56X dual core variants.
Count Leading Zeroes Instruction
--------------------------------
-The Blackfin CPU has the BITTST instruction which could be used to speed
-up the find first bit operation. The use of this instruction should
-significantly speed up the scheduling associated with a thread blocking.
+The Blackfin CPU has the BITTST instruction which could be used to speed up the
+find first bit operation. The use of this instruction should significantly
+speed up the scheduling associated with a thread blocking.
Calling Conventions
===================
This section is heavily based on content taken from the Blackfin uCLinux
-documentation wiki which is edited by Analog Devices and Arcturus
-Networks. :file:`http://docs.blackfin.uclinux.org/`
+documentation wiki which is edited by Analog Devices and Arcturus Networks.
+http://docs.blackfin.uclinux.org/
Processor Background
--------------------
-The Blackfin architecture supports a simple call and return mechanism.
-A subroutine is invoked via the call (``call``) instruction.
-This instruction saves the return address in the ``RETS`` register
-and transfers the execution to the given address.
+The Blackfin architecture supports a simple call and return mechanism. A
+subroutine is invoked via the call (``call``) instruction. This instruction
+saves the return address in the ``RETS`` register and transfers the execution
+to the given address.
-It is the called funcions responsability to use the link instruction
-to reserve space on the stack for the local variables. Returning from
-a subroutine is done by using the RTS (``RTS``) instruction which
-loads the PC with the adress stored in RETS.
+It is the called funcions responsability to use the link instruction to reserve
+space on the stack for the local variables. Returning from a subroutine is
+done by using the RTS (``RTS``) instruction which loads the PC with the adress
+stored in RETS.
-It is is important to note that the ``call`` instruction does not
-automatically save or restore any registers. It is the responsibility
-of the high-level language compiler to define the register preservation
-and usage convention.
+It is is important to note that the ``call`` instruction does not automatically
+save or restore any registers. It is the responsibility of the high-level
+language compiler to define the register preservation and usage convention.
Register Usage
--------------
-A called function may clobber all registers, except RETS, R4-R7, P3-P5,
-FP and SP. It may also modify the first 12 bytes in the caller's stack
-frame which is used as an argument area for the first three arguments
-(which are passed in R0...R3 but may be placed on the stack by the
-called function).
+A called function may clobber all registers, except RETS, R4-R7, P3-P5, FP and
+SP. It may also modify the first 12 bytes in the caller's stack frame which is
+used as an argument area for the first three arguments (which are passed in
+R0...R3 but may be placed on the stack by the called function).
Parameter Passing
-----------------
-RTEMS assumes that the Blackfin GCC calling convention is followed.
-The first three parameters are stored in registers R0, R1, and R2.
-All other parameters are put pushed on the stack. The result is returned
-through register R0.
+RTEMS assumes that the Blackfin GCC calling convention is followed. The first
+three parameters are stored in registers R0, R1, and R2. All other parameters
+are put pushed on the stack. The result is returned through register R0.
Memory Model
============
-The Blackfin family architecutre support a single unified 4 GB byte
-address space using 32-bit addresses. It maps all resources like internal
-and external memory and IO registers into separate sections of this
-common address space.
+The Blackfin family architecutre support a single unified 4 GB byte address
+space using 32-bit addresses. It maps all resources like internal and external
+memory and IO registers into separate sections of this common address space.
-The Blackfin architcture supports some form of memory
-protection via its Memory Management Unit. Since the
-Blackfin port runs in supervisior mode this memory
+The Blackfin architcture supports some form of memory protection via its Memory
+Management Unit. Since the Blackfin port runs in supervisior mode this memory
protection mechanisms are not used.
Interrupt Processing
====================
-Discussed in this chapter are the Blackfin's interrupt response and
-control mechanisms as they pertain to RTEMS. The Blackfin architecture
-support 16 kinds of interrupts broken down into Core and general-purpose
-interrupts.
+Discussed in this chapter are the Blackfin's interrupt response and control
+mechanisms as they pertain to RTEMS. The Blackfin architecture support 16 kinds
+of interrupts broken down into Core and general-purpose interrupts.
Vectoring of an Interrupt Handler
---------------------------------
-RTEMS maps levels 0 -15 directly to Blackfins event vectors EVT0 -
-EVT15. Since EVT0 - EVT6 are core events and it is suggested to use
-EVT15 and EVT15 for Software interrupts, 7 Interrupts (EVT7-EVT13)
-are left for periferical use.
+RTEMS maps levels 0 -15 directly to Blackfins event vectors EVT0 - EVT15. Since
+EVT0 - EVT6 are core events and it is suggested to use EVT15 and EVT15 for
+Software interrupts, 7 Interrupts (EVT7-EVT13) are left for periferical use.
-When installing an RTEMS interrupt handler RTEMS installs a generic
-Interrupt Handler which saves some context and enables nested interrupt
-servicing and then vectors to the users interrupt handler.
+When installing an RTEMS interrupt handler RTEMS installs a generic Interrupt
+Handler which saves some context and enables nested interrupt servicing and
+then vectors to the users interrupt handler.
Disabling of Interrupts by RTEMS
--------------------------------
-During interrupt disable critical sections, RTEMS disables interrupts to
-level four (4) before the execution of this section and restores them
-to the previous level upon completion of the section. RTEMS uses the
-instructions CLI and STI to enable and disable Interrupts. Emulation,
-Reset, NMI and Exception Interrupts are never disabled.
+During interrupt disable critical sections, RTEMS disables interrupts to level
+four (4) before the execution of this section and restores them to the previous
+level upon completion of the section. RTEMS uses the instructions CLI and STI
+to enable and disable Interrupts. Emulation, Reset, NMI and Exception
+Interrupts are never disabled.
Interrupt Stack
---------------
-The Blackfin Architecture works with two different kind of stacks,
-User and Supervisor Stack. Since RTEMS and its Application run
-in supervisor mode, all interrupts will use the interrupted
-tasks stack for execution.
+The Blackfin Architecture works with two different kind of stacks, User and
+Supervisor Stack. Since RTEMS and its Application run in supervisor mode, all
+interrupts will use the interrupted tasks stack for execution.
Default Fatal Error Processing
==============================
@@ -150,8 +145,3 @@ System Reset
------------
TBD
-
-.. COMMENT: Copyright (c) 2015 University of York.
-
-.. COMMENT: Hesham ALMatary <hmka501@york.ac.uk>
-
diff --git a/cpu_supplement/ephiphany.rst b/cpu_supplement/ephiphany.rst
index ba4b4f6..fa36119 100644
--- a/cpu_supplement/ephiphany.rst
+++ b/cpu_supplement/ephiphany.rst
@@ -1,22 +1,28 @@
.. comment SPDX-License-Identifier: CC-BY-SA-4.0
+.. COMMENT: COPYRIGHT (c) 1988-2002.
+.. COMMENT: On-Line Applications Research Corporation (OAR).
+.. COMMENT: All rights reserved.
+
Epiphany Specific Information
#############################
-This chapter discusses the`Epiphany Architecture <http://adapteva.com/docs/epiphany_sdk_ref.pdf>`_
-dependencies in this port of RTEMS. Epiphany is a chip that can come with 16 and
-64 cores, each of which can run RTEMS separately or they can work together to
-run a SMP RTEMS application.
+This chapter discusses the`Epiphany Architecture
+http://adapteva.com/docs/epiphany_sdk_ref.pdf dependencies in this port of
+RTEMS. Epiphany is a chip that can come with 16 and 64 cores, each of which can
+run RTEMS separately or they can work together to run a SMP RTEMS application.
**Architecture Documents**
-For information on the Epiphany architecture refer to the`Epiphany Architecture Reference <http://adapteva.com/docs/epiphany_arch_ref.pdf>`_.
+For information on the Epiphany architecture refer to the *Epiphany
+Architecture Reference* http://adapteva.com/docs/epiphany_arch_ref.pdf.
Calling Conventions
===================
-Please refer to the`Epiphany SDK <http://adapteva.com/docs/epiphany_sdk_ref.pdf>`_
-Appendix A: Application Binary Interface
+Please refer to the *Epiphany SDK*
+http://adapteva.com/docs/epiphany_sdk_ref.pdf Appendix A: Application Binary
+Interface
Floating Point Unit
-------------------
@@ -26,9 +32,9 @@ A floating point unit is currently not supported.
Memory Model
============
-A flat 32-bit memory model is supported, no caches. Each core has its own 32 KiB
-strictly ordered local memory along with an access to a shared 32 MiB external
-DRAM.
+A flat 32-bit memory model is supported, no caches. Each core has its own 32
+KiB strictly ordered local memory along with an access to a shared 32 MiB
+external DRAM.
Interrupt Processing
====================
@@ -63,16 +69,16 @@ There are only two levels: interrupts enabled and interrupts disabled.
Interrupt Stack
---------------
-The Epiphany RTEMS port uses a dedicated software interrupt stack.
-The stack for interrupts is allocated during interrupt driver initialization.
-When an interrupt is entered, the _ISR_Handler routine is responsible for
-switching from the interrupted task stack to RTEMS software interrupt stack.
+The Epiphany RTEMS port uses a dedicated software interrupt stack. The stack
+for interrupts is allocated during interrupt driver initialization. When an
+interrupt is entered, the _ISR_Handler routine is responsible for switching
+from the interrupted task stack to RTEMS software interrupt stack.
Default Fatal Error Processing
==============================
-The default fatal error handler for this architecture performs the
-following actions:
+The default fatal error handler for this architecture performs the following
+actions:
- disables operating system supported interrupts (IRQ),
@@ -84,10 +90,3 @@ Symmetric Multiprocessing
=========================
SMP is not supported.
-
-.. COMMENT: COPYRIGHT (c) 1988-2002.
-
-.. COMMENT: On-Line Applications Research Corporation (OAR).
-
-.. COMMENT: All rights reserved.
-
diff --git a/cpu_supplement/index.rst b/cpu_supplement/index.rst
index cee7e1e..4d5c2ac 100644
--- a/cpu_supplement/index.rst
+++ b/cpu_supplement/index.rst
@@ -4,41 +4,38 @@
RTEMS CPU Architecture Supplement
=================================
-COPYRIGHT (c) 1988 - 2015.
-
-On-Line Applications Research Corporation (OAR).
-
-The authors have used their best efforts in preparing
-this material. These efforts include the development, research,
-and testing of the theories and programs to determine their
-effectiveness. No warranty of any kind, expressed or implied,
-with regard to the software or the material contained in this
-document is provided. No liability arising out of the
-application or use of any product described in this document is
-assumed. The authors reserve the right to revise this material
-and to make changes from time to time in the content hereof
-without obligation to notify anyone of such revision or changes.
-
-The RTEMS Project is hosted at http://www.rtems.org. Any
-inquiries concerning RTEMS, its related support components, or its
-documentation should be directed to the Community Project hosted athttp://www.rtems.org.
-
-Any inquiries for commercial services including training, support, custom
-development, application development assistance should be directed tohttp://www.rtems.com.
-
-
-Table of Contents
------------------
-
-.. toctree::
-
- preface
-
+ | COPYRIGHT (c) 1988 - 2015.
+ | On-Line Applications Research Corporation (OAR).
+
+The authors have used their best efforts in preparing this material. These
+efforts include the development, research, and testing of the theories and
+programs to determine their effectiveness. No warranty of any kind, expressed
+or implied, with regard to the software or the material contained in this
+document is provided. No liability arising out of the application or use of
+any product described in this document is assumed. The authors reserve the
+right to revise this material and to make changes from time to time in the
+content hereof without obligation to notify anyone of such revision or changes.
+
+The RTEMS Project is hosted at http://www.rtems.org/. Any inquiries concerning
+RTEMS, its related support components, or its documentation should be directed
+to the Community Project hosted at http://www.rtems.org/.
+
+.. topic:: RTEMS Online Resources
+
+ ================ =============================
+ Home https://www.rtems.org/
+ Developers https://devel.rtems.org/
+ Documentation https://docs.rtems.org/
+ Bug Reporting https://devel.rtems.org/query
+ Mailing Lists https://lists.rtems.org/
+ Git Repositories https://git.rtems.org/
+ ================ =============================
.. toctree::
:maxdepth: 3
:numbered:
+ preface
port
arm
atmel_avr
@@ -58,7 +55,5 @@ Table of Contents
sparc64
command
-
* :ref:`genindex`
* :ref:`search`
-
diff --git a/cpu_supplement/intel_amd_x86.rst b/cpu_supplement/intel_amd_x86.rst
index 0597f19..37ff569 100644
--- a/cpu_supplement/intel_amd_x86.rst
+++ b/cpu_supplement/intel_amd_x86.rst
@@ -1,15 +1,19 @@
.. comment SPDX-License-Identifier: CC-BY-SA-4.0
+.. COMMENT: COPYRIGHT (c) 1988-2002.
+.. COMMENT: On-Line Applications Research Corporation (OAR).
+.. COMMENT: All rights reserved.
+.. COMMENT: Jukka Pietarinen <jukka.pietarinen@mrf.fi>, 2008,
+.. COMMENT: Micro-Research Finland Oy
+
Intel/AMD x86 Specific Information
##################################
-This chapter discusses the Intel x86 architecture dependencies
-in this port of RTEMS. This family has multiple implementations
-from multiple vendors and suffers more from having evolved rather
-than being designed for growth.
+This chapter discusses the Intel x86 architecture dependencies in this port of
+RTEMS. This family has multiple implementations from multiple vendors and
+suffers more from having evolved rather than being designed for growth.
-For information on the i386 processor, refer to the
-following documents:
+For information on the i386 processor, refer to the following documents:
- *386 Programmer's Reference Manual, Intel, Order No. 230985-002*.
@@ -23,19 +27,17 @@ following documents:
CPU Model Dependent Features
============================
-This section presents the set of features which vary
-across i386 implementations and are of importance to RTEMS.
-The set of CPU model feature macros are defined in the file``cpukit/score/cpu/i386/i386.h`` based upon the particular CPU
-model specified on the compilation command line.
+This section presents the set of features which vary across i386
+implementations and are of importance to RTEMS. The set of CPU model feature
+macros are defined in the :file:`cpukit/score/cpu/i386/i386.h` based upon the
+particular CPU model specified on the compilation command line.
bswap Instruction
-----------------
-The macro ``I386_HAS_BSWAP`` is set to 1 to indicate that
-this CPU model has the ``bswap`` instruction which
-endian swaps a thirty-two bit quantity. This instruction
-appears to be present in all CPU models
-i486's and above.
+The macro ``I386_HAS_BSWAP`` is set to 1 to indicate that this CPU model has
+the ``bswap`` instruction which endian swaps a thirty-two bit quantity. This
+instruction appears to be present in all CPU models i486's and above.
Calling Conventions
===================
@@ -43,43 +45,40 @@ Calling Conventions
Processor Background
--------------------
-The i386 architecture supports a simple yet effective
-call and return mechanism. A subroutine is invoked via the call
-(``call``) instruction. This instruction pushes the return address
-on the stack. The return from subroutine (``ret``) instruction pops
-the return address off the current stack and transfers control
-to that instruction. It is is important to note that the i386
-call and return mechanism does not automatically save or restore
-any registers. It is the responsibility of the high-level
-language compiler to define the register preservation and usage
-convention.
+The i386 architecture supports a simple yet effective call and return
+mechanism. A subroutine is invoked via the call (``call``) instruction. This
+instruction pushes the return address on the stack. The return from subroutine
+(``ret``) instruction pops the return address off the current stack and
+transfers control to that instruction. It is is important to note that the
+i386 call and return mechanism does not automatically save or restore any
+registers. It is the responsibility of the high-level language compiler to
+define the register preservation and usage convention.
Calling Mechanism
-----------------
-All RTEMS directives are invoked using a call instruction and return to
-the user application via the ret instruction.
+All RTEMS directives are invoked using a call instruction and return to the
+user application via the ret instruction.
Register Usage
--------------
-As discussed above, the call instruction does not automatically save
-any registers. RTEMS uses the registers EAX, ECX, and EDX as scratch
-registers. These registers are not preserved by RTEMS directives
-therefore, the contents of these registers should not be assumed upon
-return from any RTEMS directive.
+As discussed above, the call instruction does not automatically save any
+registers. RTEMS uses the registers EAX, ECX, and EDX as scratch registers.
+These registers are not preserved by RTEMS directives therefore, the contents
+of these registers should not be assumed upon return from any RTEMS directive.
Parameter Passing
-----------------
-RTEMS assumes that arguments are placed on the
-current stack before the directive is invoked via the call
-instruction. The first argument is assumed to be closest to the
-return address on the stack. This means that the first argument
-of the C calling sequence is pushed last. The following
-pseudo-code illustrates the typical sequence used to call a
-RTEMS directive with three (3) arguments:
-.. code:: c
+RTEMS assumes that arguments are placed on the current stack before the
+directive is invoked via the call instruction. The first argument is assumed
+to be closest to the return address on the stack. This means that the first
+argument of the C calling sequence is pushed last. The following pseudo-code
+illustrates the typical sequence used to call a RTEMS directive with three (3)
+arguments:
+
+.. code-block:: c
push third argument
push second argument
@@ -87,11 +86,10 @@ RTEMS directive with three (3) arguments:
invoke directive
remove arguments from the stack
-The arguments to RTEMS are typically pushed onto the
-stack using a push instruction. These arguments must be removed
-from the stack after control is returned to the caller. This
-removal is typically accomplished by adding the size of the
-argument list in bytes to the stack pointer.
+The arguments to RTEMS are typically pushed onto the stack using a push
+instruction. These arguments must be removed from the stack after control is
+returned to the caller. This removal is typically accomplished by adding the
+size of the argument list in bytes to the stack pointer.
Memory Model
============
@@ -99,54 +97,47 @@ Memory Model
Flat Memory Model
-----------------
-RTEMS supports the i386 protected mode, flat memory
-model with paging disabled. In this mode, the i386
-automatically converts every address from a logical to a
-physical address each time it is used. The i386 uses
-information provided in the segment registers and the Global
-Descriptor Table to convert these addresses. RTEMS assumes the
-existence of the following segments:
+RTEMS supports the i386 protected mode, flat memory model with paging disabled.
+In this mode, the i386 automatically converts every address from a logical to a
+physical address each time it is used. The i386 uses information provided in
+the segment registers and the Global Descriptor Table to convert these
+addresses. RTEMS assumes the existence of the following segments:
-- a single code segment at protection level (0) which
- contains all application and executive code.
+- a single code segment at protection level (0) which contains all application
+ and executive code.
-- a single data segment at protection level zero (0) which
- contains all application and executive data.
+- a single data segment at protection level zero (0) which contains all
+ application and executive data.
-The i386 segment registers and associated selectors
-must be initialized when the initialize_executive directive is
-invoked. RTEMS treats the segment registers as system registers
-and does not modify or context switch them.
+The i386 segment registers and associated selectors must be initialized when
+the initialize_executive directive is invoked. RTEMS treats the segment
+registers as system registers and does not modify or context switch them.
-This i386 memory model supports a flat 32-bit address
-space with addresses ranging from 0x00000000 to 0xFFFFFFFF (4
-gigabytes). Each address is represented by a 32-bit value and
-is byte addressable. The address may be used to reference a
-single byte, half-word (2-bytes), or word (4 bytes).
+This i386 memory model supports a flat 32-bit address space with addresses
+ranging from 0x00000000 to 0xFFFFFFFF (4 gigabytes). Each address is
+represented by a 32-bit value and is byte addressable. The address may be used
+to reference a single byte, half-word (2-bytes), or word (4 bytes).
Interrupt Processing
====================
-Although RTEMS hides many of the processor
-dependent details of interrupt processing, it is important to
-understand how the RTEMS interrupt manager is mapped onto the
-processor's unique architecture. Discussed in this chapter are
-the the processor's response and control mechanisms as they
-pertain to RTEMS.
+Although RTEMS hides many of the processor dependent details of interrupt
+processing, it is important to understand how the RTEMS interrupt manager is
+mapped onto the processor's unique architecture. Discussed in this chapter are
+the the processor's response and control mechanisms as they pertain to RTEMS.
Vectoring of Interrupt Handler
------------------------------
-Although the i386 supports multiple privilege levels,
-RTEMS and all user software executes at privilege level 0. This
-decision was made by the RTEMS designers to enhance
-compatibility with processors which do not provide sophisticated
-protection facilities like those of the i386. This decision
-greatly simplifies the discussion of i386 processing, as one
-need only consider interrupts without privilege transitions.
+Although the i386 supports multiple privilege levels, RTEMS and all user
+software executes at privilege level 0. This decision was made by the RTEMS
+designers to enhance compatibility with processors which do not provide
+sophisticated protection facilities like those of the i386. This decision
+greatly simplifies the discussion of i386 processing, as one need only consider
+interrupts without privilege transitions.
-Upon receipt of an interrupt the i386 automatically
-performs the following actions:
+Upon receipt of an interrupt the i386 automatically performs the following
+actions:
- pushes the EFLAGS register
@@ -154,15 +145,13 @@ performs the following actions:
- vectors to the interrupt service routine (ISR).
-A nested interrupt is processed similarly by the
-i386.
+A nested interrupt is processed similarly by the i386.
Interrupt Stack Frame
---------------------
-The structure of the Interrupt Stack Frame for the
-i386 which is placed on the interrupt stack by the processor in
-response to an interrupt is as follows:
+The structure of the Interrupt Stack Frame for the i386 which is placed on the
+interrupt stack by the processor in response to an interrupt is as follows:
+----------------------+-------+
| Old EFLAGS Register | ESP+8 |
@@ -176,37 +165,33 @@ response to an interrupt is as follows:
Interrupt Levels
----------------
-Although RTEMS supports 256 interrupt levels, the
-i386 only supports two - enabled and disabled. Interrupts are
-enabled when the interrupt-enable flag (IF) in the extended
-flags (EFLAGS) is set. Conversely, interrupt processing is
-inhibited when the IF is cleared. During a non-maskable
-interrupt, all other interrupts, including other non-maskable
-ones, are inhibited.
+Although RTEMS supports 256 interrupt levels, the i386 only supports two -
+enabled and disabled. Interrupts are enabled when the interrupt-enable flag
+(IF) in the extended flags (EFLAGS) is set. Conversely, interrupt processing
+is inhibited when the IF is cleared. During a non-maskable interrupt, all
+other interrupts, including other non-maskable ones, are inhibited.
RTEMS interrupt levels 0 and 1 such that level zero
-(0) indicates that interrupts are fully enabled and level one
-that interrupts are disabled. All other RTEMS interrupt levels
-are undefined and their behavior is unpredictable.
+(0) indicates that interrupts are fully enabled and level one that interrupts
+are disabled. All other RTEMS interrupt levels are undefined and their
+behavior is unpredictable.
Interrupt Stack
---------------
-The i386 family does not support a dedicated hardware
-interrupt stack. On this processor, RTEMS allocates and manages
-a dedicated interrupt stack. As part of vectoring a non-nested
-interrupt service routine, RTEMS switches from the stack of the
-interrupted task to a dedicated interrupt stack. When a
-non-nested interrupt returns, RTEMS switches back to the stack
-of the interrupted stack. The current stack pointer is not
-altered by RTEMS on nested interrupt.
+The i386 family does not support a dedicated hardware interrupt stack. On this
+processor, RTEMS allocates and manages a dedicated interrupt stack. As part of
+vectoring a non-nested interrupt service routine, RTEMS switches from the stack
+of the interrupted task to a dedicated interrupt stack. When a non-nested
+interrupt returns, RTEMS switches back to the stack of the interrupted stack.
+The current stack pointer is not altered by RTEMS on nested interrupt.
Default Fatal Error Processing
==============================
The default fatal error handler for this architecture disables processor
-interrupts, places the error code in EAX, and executes a HLT instruction
-to halt the processor.
+interrupts, places the error code in EAX, and executes a HLT instruction to
+halt the processor.
Symmetric Multiprocessing
=========================
@@ -224,36 +209,34 @@ Board Support Packages
System Reset
------------
-An RTEMS based application is initiated when the i386 processor is reset.
-When the i386 is reset,
+An RTEMS based application is initiated when the i386 processor is reset. When
+the i386 is reset,
-- The EAX register is set to indicate the results of the processor's
- power-up self test. If the self-test was not executed, the contents of
- this register are undefined. Otherwise, a non-zero value indicates the
- processor is faulty and a zero value indicates a successful self-test.
+- The EAX register is set to indicate the results of the processor's power-up
+ self test. If the self-test was not executed, the contents of this register
+ are undefined. Otherwise, a non-zero value indicates the processor is faulty
+ and a zero value indicates a successful self-test.
-- The DX register holds a component identifier and revision level. DH
- contains 3 to indicate an i386 component and DL contains a unique revision
- level indicator.
+- The DX register holds a component identifier and revision level. DH contains
+ 3 to indicate an i386 component and DL contains a unique revision level
+ indicator.
-- Control register zero (CR0) is set such that the processor is in real
- mode with paging disabled. Other portions of CR0 are used to indicate the
+- Control register zero (CR0) is set such that the processor is in real mode
+ with paging disabled. Other portions of CR0 are used to indicate the
presence of a numeric coprocessor.
-- All bits in the extended flags register (EFLAG) which are not
- permanently set are cleared. This inhibits all maskable interrupts.
+- All bits in the extended flags register (EFLAG) which are not permanently set
+ are cleared. This inhibits all maskable interrupts.
-- The Interrupt Descriptor Register (IDTR) is set to point at address
- zero.
+- The Interrupt Descriptor Register (IDTR) is set to point at address zero.
- All segment registers are set to zero.
-- The instruction pointer is set to 0x0000FFF0. The first instruction
- executed after a reset is actually at 0xFFFFFFF0 because the i386 asserts
- the upper twelve address until the first intersegment (FAR) JMP or CALL
- instruction. When a JMP or CALL is executed, the upper twelve address
- lines are lowered and the processor begins executing in the first megabyte
- of memory.
+- The instruction pointer is set to 0x0000FFF0. The first instruction executed
+ after a reset is actually at 0xFFFFFFF0 because the i386 asserts the upper
+ twelve address until the first intersegment (FAR) JMP or CALL instruction.
+ When a JMP or CALL is executed, the upper twelve address lines are lowered
+ and the processor begins executing in the first megabyte of memory.
Typically, an intersegment JMP to the application's initialization code is
placed at address 0xFFFFFFF0.
@@ -261,62 +244,49 @@ placed at address 0xFFFFFFF0.
Processor Initialization
------------------------
-This initialization code is responsible for initializing all data
-structures required by the i386 in protected mode and for actually entering
-protected mode. The i386 must be placed in protected mode and the segment
-registers and associated selectors must be initialized before the
-initialize_executive directive is invoked.
-
-The initialization code is responsible for initializing the Global
-Descriptor Table such that the i386 is in the thirty-two bit flat memory
-model with paging disabled. In this mode, the i386 automatically converts
-every address from a logical to a physical address each time it is used.
-For more information on the memory model used by RTEMS, please refer to the
-Memory Model chapter in this document.
-
-Since the processor is in real mode upon reset, the processor must be
-switched to protected mode before RTEMS can execute. Before switching to
-protected mode, at least one descriptor table and two descriptors must be
-created. Descriptors are needed for a code segment and a data segment. (
-This will give you the flat memory model.) The stack can be placed in a
-normal read/write data segment, so no descriptor for the stack is needed.
-Before the GDT can be used, the base address and limit must be loaded into
-the GDTR register using an LGDT instruction.
-
-If the hardware allows an NMI to be generated, you need to create the IDT
-and a gate for the NMI interrupt handler. Before the IDT can be used, the
-base address and limit for the idt must be loaded into the IDTR register
-using an LIDT instruction.
-
-Protected mode is entered by setting thye PE bit in the CR0 register.
-Either a LMSW or MOV CR0 instruction may be used to set this bit. Because
-the processor overlaps the interpretation of several instructions, it is
-necessary to discard the instructions from the read-ahead cache. A JMP
-instruction immediately after the LMSW changes the flow and empties the
-processor if intructions which have been pre-fetched and/or decoded. At
-this point, the processor is in protected mode and begins to perform
-protected mode application initialization.
-
-If the application requires that the IDTR be some value besides zero, then
-it should set it to the required value at this point. All tasks share the
-same i386 IDTR value. Because interrupts are enabled automatically by
-RTEMS as part of the initialize_executive directive, the IDTR MUST be set
-properly before this directive is invoked to insure correct interrupt
-vectoring. If processor caching is to be utilized, then it should be
-enabled during the reset application initialization code. The reset code
-which is executed before the call to initialize_executive has the following
-requirements:
-
-For more information regarding the i386 data structures and their
-contents, refer to Intel's 386 Programmer's Reference Manual.
-
-.. COMMENT: COPYRIGHT (c) 1988-2002.
-
-.. COMMENT: On-Line Applications Research Corporation (OAR).
-
-.. COMMENT: All rights reserved.
-
-.. COMMENT: Jukka Pietarinen <jukka.pietarinen@mrf.fi>, 2008,
-
-.. COMMENT: Micro-Research Finland Oy
-
+This initialization code is responsible for initializing all data structures
+required by the i386 in protected mode and for actually entering protected
+mode. The i386 must be placed in protected mode and the segment registers and
+associated selectors must be initialized before the initialize_executive
+directive is invoked.
+
+The initialization code is responsible for initializing the Global Descriptor
+Table such that the i386 is in the thirty-two bit flat memory model with paging
+disabled. In this mode, the i386 automatically converts every address from a
+logical to a physical address each time it is used. For more information on
+the memory model used by RTEMS, please refer to the Memory Model chapter in
+this document.
+
+Since the processor is in real mode upon reset, the processor must be switched
+to protected mode before RTEMS can execute. Before switching to protected
+mode, at least one descriptor table and two descriptors must be created.
+Descriptors are needed for a code segment and a data segment. ( This will give
+you the flat memory model.) The stack can be placed in a normal read/write
+data segment, so no descriptor for the stack is needed. Before the GDT can be
+used, the base address and limit must be loaded into the GDTR register using an
+LGDT instruction.
+
+If the hardware allows an NMI to be generated, you need to create the IDT and a
+gate for the NMI interrupt handler. Before the IDT can be used, the base
+address and limit for the idt must be loaded into the IDTR register using an
+LIDT instruction.
+
+Protected mode is entered by setting thye PE bit in the CR0 register. Either a
+LMSW or MOV CR0 instruction may be used to set this bit. Because the processor
+overlaps the interpretation of several instructions, it is necessary to discard
+the instructions from the read-ahead cache. A JMP instruction immediately after
+the LMSW changes the flow and empties the processor if intructions which have
+been pre-fetched and/or decoded. At this point, the processor is in protected
+mode and begins to perform protected mode application initialization.
+
+If the application requires that the IDTR be some value besides zero, then it
+should set it to the required value at this point. All tasks share the same
+i386 IDTR value. Because interrupts are enabled automatically by RTEMS as part
+of the initialize_executive directive, the IDTR MUST be set properly before
+this directive is invoked to insure correct interrupt vectoring. If processor
+caching is to be utilized, then it should be enabled during the reset
+application initialization code. The reset code which is executed before the
+call to initialize_executive has the following requirements:
+
+For more information regarding the i386 data structures and their contents,
+refer to Intel's 386 Programmer's Reference Manual.
diff --git a/cpu_supplement/lattice_micro32.rst b/cpu_supplement/lattice_micro32.rst
index b141dd2..620cadf 100644
--- a/cpu_supplement/lattice_micro32.rst
+++ b/cpu_supplement/lattice_micro32.rst
@@ -1,27 +1,30 @@
.. comment SPDX-License-Identifier: CC-BY-SA-4.0
+.. COMMENT: Copyright (c) 2014 embedded brains GmbH. All rights reserved.
+
Lattice Mico32 Specific Information
###################################
-This chaper discusses the Lattice Mico32 architecture dependencies in
-this port of RTEMS. The Lattice Mico32 is a 32-bit Harvard, RISC
-architecture "soft" microprocessor, available for free with an open IP
-core licensing agreement. Although mainly targeted for Lattice FPGA
-devices the microprocessor can be implemented on other vendors' FPGAs,
-too.
+This chaper discusses the Lattice Mico32 architecture dependencies in this port
+of RTEMS. The Lattice Mico32 is a 32-bit Harvard, RISC architecture "soft"
+microprocessor, available for free with an open IP core licensing
+agreement. Although mainly targeted for Lattice FPGA devices the microprocessor
+can be implemented on other vendors' FPGAs, too.
**Architecture Documents**
-For information on the Lattice Mico32 architecture, refer to the
-following documents available from Lattice Semiconductor:file:`http://www.latticesemi.com/`.
+For information on the Lattice Mico32 architecture, refer to the following
+documents available from Lattice Semiconductor http://www.latticesemi.com/.
-- *"LatticeMico32 Processor Reference Manual"*:file:`http://www.latticesemi.com/dynamic/view_document.cfm?document_id=20890`
+- *"LatticeMico32 Processor Reference Manual"*
+ http://www.latticesemi.com/dynamic/view_document.cfm?document_id=20890
CPU Model Dependent Features
============================
-The Lattice Mico32 architecture allows for different configurations of
-the processor. This port is based on the assumption that the following options are implemented:
+The Lattice Mico32 architecture allows for different configurations of the
+processor. This port is based on the assumption that the following options are
+implemented:
- hardware multiplier
@@ -40,11 +43,11 @@ the processor. This port is based on the assumption that the following options a
Register Architecture
=====================
-This section gives a brief introduction to the register architecture
-of the Lattice Mico32 processor.
+This section gives a brief introduction to the register architecture of the
+Lattice Mico32 processor.
-The Lattice Mico32 is a RISC archictecture processor with a
-32-register file of 32-bit registers.
+The Lattice Mico32 is a RISC archictecture processor with a 32-register file of
+32-bit registers.
Register Name
@@ -82,8 +85,8 @@ r31/ba
breakpoint address
-Note that on processor startup all register values are undefined
-including r0, thus r0 has to be initialized to zero.
+Note that on processor startup all register values are undefined including r0,
+thus r0 has to be initialized to zero.
Calling Conventions
===================
@@ -91,95 +94,63 @@ Calling Conventions
Calling Mechanism
-----------------
-A call instruction places the return address to register r29 and a
-return from subroutine (ret) is actually a branch to r29/ra.
+A call instruction places the return address to register r29 and a return from
+subroutine (ret) is actually a branch to r29/ra.
Register Usage
--------------
-A subroutine may freely use registers r1 to r10 which are *not*
-preserved across subroutine invocations.
+A subroutine may freely use registers r1 to r10 which are *not* preserved
+across subroutine invocations.
Parameter Passing
-----------------
-When calling a C function the first eight arguments are stored in
-registers r1 to r8. Registers r1 and r2 hold the return value.
+When calling a C function the first eight arguments are stored in registers r1
+to r8. Registers r1 and r2 hold the return value.
Memory Model
============
-The Lattice Mico32 processor supports a flat memory model with a 4
-Gbyte address space with 32-bit addresses.
+The Lattice Mico32 processor supports a flat memory model with a 4 Gbyte
+address space with 32-bit addresses.
The following data types are supported:
-Type
-
-Bits
-
-C Compiler Type
-
-unsigned byte
-
-8
-
-unsigned char
-
-signed byte
-
-8
-
-char
-
-unsigned half-word
-
-16
-
-unsigned short
+================== ==== ======================
+Type Bits C Compiler Type
+================== ==== ======================
+unsigned byte 8 unsigned char
+signed byte 8 char
+unsigned half-word 16 unsigned short
+signed half-word 16 short
+unsigned word 32 unsigned int / unsigned long
+signed word 32 int / long
+================== ==== ======================
-signed half-word
-
-16
-
-short
-
-unsigned word
-
-32
-
-unsigned int / unsigned long
-
-signed word
-
-32
-
-int / long
-
-Data accesses need to be aligned, with unaligned accesses result are
-undefined.
+Data accesses need to be aligned, with unaligned accesses result are undefined.
Interrupt Processing
====================
-The Lattice Mico32 has 32 interrupt lines which are however served by
-only one exception vector. When an interrupt occurs following happens:
+The Lattice Mico32 has 32 interrupt lines which are however served by only one
+exception vector. When an interrupt occurs following happens:
- address of next instruction placed in r30/ea
-- IE field of IE CSR saved to EIE field and IE field cleared preventing further exceptions from occuring.
+- IE field of IE CSR saved to EIE field and IE field cleared preventing further
+ exceptions from occuring.
- branch to interrupt exception address EBA CSR + 0xC0
-The interrupt exception handler determines from the state of the
-interrupt pending registers (IP CSR) and interrupt enable register (IE
-CSR) which interrupt to serve and jumps to the interrupt routine
-pointed to by the corresponding interrupt vector.
+The interrupt exception handler determines from the state of the interrupt
+pending registers (IP CSR) and interrupt enable register (IE CSR) which
+interrupt to serve and jumps to the interrupt routine pointed to by the
+corresponding interrupt vector.
-For now there is no dedicated interrupt stack so every task in
-the system MUST have enough stack space to accommodate the worst
-case stack usage of that particular task and the interrupt
-service routines COMBINED.
+For now there is no dedicated interrupt stack so every task in the system MUST
+have enough stack space to accommodate the worst case stack usage of that
+particular task and the interrupt service routines COMBINED.
Nested interrupts are not supported.
@@ -187,18 +158,17 @@ Default Fatal Error Processing
==============================
Upon detection of a fatal error by either the application or RTEMS during
-initialization the ``rtems_fatal_error_occurred`` directive supplied
-by the Fatal Error Manager is invoked. The Fatal Error Manager will
-invoke the user-supplied fatal error handlers. If no user-supplied
-handlers are configured or all of them return without taking action to
-shutdown the processor or reset, a default fatal error handler is invoked.
+initialization the ``rtems_fatal_error_occurred`` directive supplied by the
+Fatal Error Manager is invoked. The Fatal Error Manager will invoke the
+user-supplied fatal error handlers. If no user-supplied handlers are
+configured or all of them return without taking action to shutdown the
+processor or reset, a default fatal error handler is invoked.
Most of the action performed as part of processing the fatal error are
-described in detail in the Fatal Error Manager chapter in the User's
-Guide. However, the if no user provided extension or BSP specific fatal
-error handler takes action, the final default action is to invoke a
-CPU architecture specific function. Typically this function disables
-interrupts and halts the processor.
+described in detail in the Fatal Error Manager chapter in the User's Guide.
+However, the if no user provided extension or BSP specific fatal error handler
+takes action, the final default action is to invoke a CPU architecture specific
+function. Typically this function disables interrupts and halts the processor.
In each of the architecture specific chapters, this describes the precise
operations of the default CPU specific fatal error handler.
@@ -216,20 +186,16 @@ Thread-local storage is not implemented.
Board Support Packages
======================
-An RTEMS Board Support Package (BSP) must be designed to support a
-particular processor model and target board combination.
+An RTEMS Board Support Package (BSP) must be designed to support a particular
+processor model and target board combination.
-In each of the architecture specific chapters, this section will present
-a discussion of architecture specific BSP issues. For more information
-on developing a BSP, refer to BSP and Device Driver Development Guide
-and the chapter titled Board Support Packages in the RTEMS
-Applications User's Guide.
+In each of the architecture specific chapters, this section will present a
+discussion of architecture specific BSP issues. For more information on
+developing a BSP, refer to BSP and Device Driver Development Guide and the
+chapter titled Board Support Packages in the RTEMS Applications User's Guide.
System Reset
------------
-An RTEMS based application is initiated or re-initiated when the processor
-is reset.
-
-.. COMMENT: Copyright (c) 2014 embedded brains GmbH. All rights reserved.
-
+An RTEMS based application is initiated or re-initiated when the processor is
+reset.
diff --git a/cpu_supplement/m68xxx_and_coldfire.rst b/cpu_supplement/m68xxx_and_coldfire.rst
index 0383847..d448276 100644
--- a/cpu_supplement/m68xxx_and_coldfire.rst
+++ b/cpu_supplement/m68xxx_and_coldfire.rst
@@ -1,21 +1,24 @@
.. comment SPDX-License-Identifier: CC-BY-SA-4.0
+.. COMMENT: Copyright (c) 2014 embedded brains GmbH. All rights reserved.
+
M68xxx and Coldfire Specific Information
########################################
-This chapter discusses the Freescale (formerly Motorola) MC68xxx
-and Coldfire architectural dependencies. The MC68xxx family has a
-wide variety of CPU models within it based upon different CPU core
-implementations. Ignoring the Coldfire parts, the part numbers for
-these models are generally divided into MC680xx and MC683xx. The MC680xx
-models are more general purpose processors with no integrated peripherals.
-The MC683xx models, on the other hand, are more specialized and have a
-variety of peripherals on chip including sophisticated timers and serial
-communications controllers.
+This chapter discusses the Freescale (formerly Motorola) MC68xxx and Coldfire
+architectural dependencies. The MC68xxx family has a wide variety of CPU
+models within it based upon different CPU core implementations. Ignoring the
+Coldfire parts, the part numbers for these models are generally divided into
+MC680xx and MC683xx. The MC680xx models are more general purpose processors
+with no integrated peripherals. The MC683xx models, on the other hand, are
+more specialized and have a variety of peripherals on chip including
+sophisticated timers and serial communications controllers.
**Architecture Documents**
-For information on the MC68xxx and Coldfire architecture, refer to the following documents available from Freescale website (:file:`http//www.freescale.com/`):
+For information on the MC68xxx and Coldfire architecture, refer to the
+following documents available from Freescale website
+(http//www.freescale.com/):
- *M68000 Family Reference, Motorola, FR68K/D*.
@@ -27,82 +30,81 @@ For information on the MC68xxx and Coldfire architecture, refer to the following
CPU Model Dependent Features
============================
-This section presents the set of features which vary
-across m68k/Coldfire implementations that are of importance to RTEMS.
-The set of CPU model feature macros are defined in the file``cpukit/score/cpu/m68k/m68k.h`` based upon the particular CPU
-model selected on the compilation command line.
+This section presents the set of features which vary across m68k/Coldfire
+implementations that are of importance to RTEMS. The set of CPU model feature
+macros are defined in the file :file:`cpukit/score/cpu/m68k/m68k.h` based upon
+the particular CPU model selected on the compilation command line.
BFFFO Instruction
-----------------
-The macro ``M68K_HAS_BFFFO`` is set to 1 to indicate that
-this CPU model has the bfffo instruction.
+The macro ``M68K_HAS_BFFFO`` is set to 1 to indicate that this CPU model has
+the bfffo instruction.
Vector Base Register
--------------------
-The macro ``M68K_HAS_VBR`` is set to 1 to indicate that
-this CPU model has a vector base register (vbr).
+The macro ``M68K_HAS_VBR`` is set to 1 to indicate that this CPU model has a
+vector base register (vbr).
Separate Stacks
---------------
-The macro ``M68K_HAS_SEPARATE_STACKS`` is set to 1 to
-indicate that this CPU model has separate interrupt, user, and
-supervisor mode stacks.
+The macro ``M68K_HAS_SEPARATE_STACKS`` is set to 1 to indicate that this CPU
+model has separate interrupt, user, and supervisor mode stacks.
Pre-Indexing Address Mode
-------------------------
-The macro ``M68K_HAS_PREINDEXING`` is set to 1 to indicate that
-this CPU model has the pre-indexing address mode.
+The macro ``M68K_HAS_PREINDEXING`` is set to 1 to indicate that this CPU model
+has the pre-indexing address mode.
Extend Byte to Long Instruction
-------------------------------
-The macro ``M68K_HAS_EXTB_L`` is set to 1 to indicate that this CPU model
-has the extb.l instruction. This instruction is supposed to be available
-in all models based on the cpu32 core as well as mc68020 and up models.
+The macro ``M68K_HAS_EXTB_L`` is set to 1 to indicate that this CPU model has
+the extb.l instruction. This instruction is supposed to be available in all
+models based on the cpu32 core as well as mc68020 and up models.
Calling Conventions
===================
-The MC68xxx architecture supports a simple yet effective call and
-return mechanism. A subroutine is invoked via the branch to subroutine
-(``bsr``) or the jump to subroutine (``jsr``) instructions.
-These instructions push the return address on the current stack.
-The return from subroutine (``rts``) instruction pops the return
-address off the current stack and transfers control to that instruction.
-It is is important to note that the MC68xxx call and return mechanism does
-not automatically save or restore any registers. It is the responsibility
-of the high-level language compiler to define the register preservation
-and usage convention.
+The MC68xxx architecture supports a simple yet effective call and return
+mechanism. A subroutine is invoked via the branch to subroutine (``bsr``) or
+the jump to subroutine (``jsr``) instructions. These instructions push the
+return address on the current stack. The return from subroutine (``rts``)
+instruction pops the return address off the current stack and transfers control
+to that instruction. It is is important to note that the MC68xxx call and
+return mechanism does not automatically save or restore any registers. It is
+the responsibility of the high-level language compiler to define the register
+preservation and usage convention.
Calling Mechanism
-----------------
-All RTEMS directives are invoked using either a ``bsr`` or ``jsr``
-instruction and return to the user application via the rts instruction.
+All RTEMS directives are invoked using either a ``bsr`` or ``jsr`` instruction
+and return to the user application via the rts instruction.
Register Usage
--------------
-As discussed above, the ``bsr`` and ``jsr`` instructions do not
-automatically save any registers. RTEMS uses the registers D0, D1,
-A0, and A1 as scratch registers. These registers are not preserved by
-RTEMS directives therefore, the contents of these registers should not
-be assumed upon return from any RTEMS directive.
+As discussed above, the ``bsr`` and ``jsr`` instructions do not automatically
+save any registers. RTEMS uses the registers D0, D1, A0, and A1 as scratch
+registers. These registers are not preserved by RTEMS directives therefore,
+the contents of these registers should not be assumed upon return from any
+RTEMS directive.
Parameter Passing
-----------------
-RTEMS assumes that arguments are placed on the current stack before
-the directive is invoked via the bsr or jsr instruction. The first
-argument is assumed to be closest to the return address on the stack.
-This means that the first argument of the C calling sequence is pushed
-last. The following pseudo-code illustrates the typical sequence used
-to call a RTEMS directive with three (3) arguments:
-.. code:: c
+RTEMS assumes that arguments are placed on the current stack before the
+directive is invoked via the bsr or jsr instruction. The first argument is
+assumed to be closest to the return address on the stack. This means that the
+first argument of the C calling sequence is pushed last. The following
+pseudo-code illustrates the typical sequence used to call a RTEMS directive
+with three (3) arguments:
+
+.. code-block:: c
push third argument
push second argument
@@ -111,93 +113,84 @@ to call a RTEMS directive with three (3) arguments:
remove arguments from the stack
The arguments to RTEMS are typically pushed onto the stack using a move
-instruction with a pre-decremented stack pointer as the destination.
-These arguments must be removed from the stack after control is returned
-to the caller. This removal is typically accomplished by adding the
-size of the argument list in bytes to the current stack pointer.
+instruction with a pre-decremented stack pointer as the destination. These
+arguments must be removed from the stack after control is returned to the
+caller. This removal is typically accomplished by adding the size of the
+argument list in bytes to the current stack pointer.
Memory Model
============
-The MC68xxx family supports a flat 32-bit address
-space with addresses ranging from 0x00000000 to 0xFFFFFFFF (4
-gigabytes). Each address is represented by a 32-bit value and
-is byte addressable. The address may be used to reference a
-single byte, word (2-bytes), or long word (4 bytes). Memory
-accesses within this address space are performed in big endian
-fashion by the processors in this family.
-
-Some of the MC68xxx family members such as the
-MC68020, MC68030, and MC68040 support virtual memory and
-segmentation. The MC68020 requires external hardware support
-such as the MC68851 Paged Memory Management Unit coprocessor
-which is typically used to perform address translations for
-these systems. RTEMS does not support virtual memory or
-segmentation on any of the MC68xxx family members.
+The MC68xxx family supports a flat 32-bit address space with addresses ranging
+from 0x00000000 to 0xFFFFFFFF (4 gigabytes). Each address is represented by a
+32-bit value and is byte addressable. The address may be used to reference a
+single byte, word (2-bytes), or long word (4 bytes). Memory accesses within
+this address space are performed in big endian fashion by the processors in
+this family.
+
+Some of the MC68xxx family members such as the MC68020, MC68030, and MC68040
+support virtual memory and segmentation. The MC68020 requires external
+hardware support such as the MC68851 Paged Memory Management Unit coprocessor
+which is typically used to perform address translations for these systems.
+RTEMS does not support virtual memory or segmentation on any of the MC68xxx
+family members.
Interrupt Processing
====================
-Discussed in this section are the MC68xxx's interrupt response and
-control mechanisms as they pertain to RTEMS.
+Discussed in this section are the MC68xxx's interrupt response and control
+mechanisms as they pertain to RTEMS.
Vectoring of an Interrupt Handler
---------------------------------
-Depending on whether or not the particular CPU supports a separate
-interrupt stack, the MC68xxx family has two different interrupt handling
-models.
+Depending on whether or not the particular CPU supports a separate interrupt
+stack, the MC68xxx family has two different interrupt handling models.
Models Without Separate Interrupt Stacks
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Upon receipt of an interrupt the MC68xxx family members without separate
-interrupt stacks automatically perform the following actions:
-
-- To Be Written
+interrupt stacks automatically use software to switch stacks.
Models With Separate Interrupt Stacks
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-Upon receipt of an interrupt the MC68xxx family members with separate
-interrupt stacks automatically perform the following actions:
+Upon receipt of an interrupt the MC68xxx family members with separate interrupt
+stacks automatically perform the following actions:
- saves the current status register (SR),
-- clears the master/interrupt (M) bit of the SR to
- indicate the switch from master state to interrupt state,
+- clears the master/interrupt (M) bit of the SR to indicate the switch from
+ master state to interrupt state,
- sets the privilege mode to supervisor,
- suppresses tracing,
-- sets the interrupt mask level equal to the level of the
- interrupt being serviced,
+- sets the interrupt mask level equal to the level of the interrupt being
+ serviced,
-- pushes an interrupt stack frame (ISF), which includes
- the program counter (PC), the status register (SR), and the
- format/exception vector offset (FVO) word, onto the supervisor
- and interrupt stacks,
+- pushes an interrupt stack frame (ISF), which includes the program counter
+ (PC), the status register (SR), and the format/exception vector offset (FVO)
+ word, onto the supervisor and interrupt stacks,
-- switches the current stack to the interrupt stack and
- vectors to an interrupt service routine (ISR). If the ISR was
- installed with the interrupt_catch directive, then the RTEMS
- interrupt handler will begin execution. The RTEMS interrupt
- handler saves all registers which are not preserved according to
+- switches the current stack to the interrupt stack and vectors to an interrupt
+ service routine (ISR). If the ISR was installed with the interrupt_catch
+ directive, then the RTEMS interrupt handler will begin execution. The RTEMS
+ interrupt handler saves all registers which are not preserved according to
the calling conventions and invokes the application's ISR.
-A nested interrupt is processed similarly by these
-CPU models with the exception that only a single ISF is placed
-on the interrupt stack and the current stack need not be
-switched.
+A nested interrupt is processed similarly by these CPU models with the
+exception that only a single ISF is placed on the interrupt stack and the
+current stack need not be switched.
-The FVO word in the Interrupt Stack Frame is examined
-by RTEMS to determine when an outer most interrupt is being
-exited. Since the FVO is used by RTEMS for this purpose, the
-user application code MUST NOT modify this field.
+The FVO word in the Interrupt Stack Frame is examined by RTEMS to determine
+when an outer most interrupt is being exited. Since the FVO is used by RTEMS
+for this purpose, the user application code MUST NOT modify this field.
-The following shows the Interrupt Stack Frame for
-MC68xxx CPU models with separate interrupt stacks:
+The following shows the Interrupt Stack Frame for MC68xxx CPU models with
+separate interrupt stacks:
+----------------------+-----+
| Status Register | 0x0 |
@@ -213,22 +206,22 @@ MC68xxx CPU models with separate interrupt stacks:
CPU Models Without VBR and RAM at 0
-----------------------------------
-This is from a post by Zoltan Kocsi <zoltan@bendor.com.au> and is
-a nice trick in certain situations. In his words:
+This is from a post by Zoltan Kocsi <zoltan@bendor.com.au> and is a nice trick
+in certain situations. In his words:
-I think somebody on this list asked about the interupt vector handling
-w/o VBR and RAM at 0. The usual trick is to initialise the vector table
-(except the first 2 two entries, of course) to point to the same location
-BUT you also add the vector number times 0x1000000 to them. That is,
-bits 31-24 contain the vector number and 23-0 the address of the common
-handler. Since the PC is 32 bit wide but the actual address bus is only
-24, the top byte will be in the PC but will be ignored when jumping onto
-your routine.
+I think somebody on this list asked about the interupt vector handling w/o VBR
+and RAM at 0. The usual trick is to initialise the vector table (except the
+first 2 two entries, of course) to point to the same location BUT you also add
+the vector number times 0x1000000 to them. That is, bits 31-24 contain the
+vector number and 23-0 the address of the common handler. Since the PC is 32
+bit wide but the actual address bus is only 24, the top byte will be in the PC
+but will be ignored when jumping onto your routine.
-Then your common interrupt routine gets this info by loading the PC
-into some register and based on that info, you can jump to a vector in
-a vector table pointed by a virtual VBR:
-.. code:: c
+Then your common interrupt routine gets this info by loading the PC into some
+register and based on that info, you can jump to a vector in a vector table
+pointed by a virtual VBR:
+
+.. code-block:: c
//
// Real vector table at 0
@@ -247,51 +240,50 @@ a vector table pointed by a virtual VBR:
// routine will see exactly what it would see if it was called
// directly from the HW vector table at 0.
//
- .comm VBR,4,2 // This defines the 'virtual' VBR
- // From C: extern void \*VBR;
+ .comm VBR,4,2 // This defines the 'virtual' VBR
+ // From C: extern void *VBR;
myhandler: // At entry, PC contains the full vector
- move.l %d0,-(%sp) // Save d0
- move.l %a0,-(%sp) // Save a0
- lea 0(%pc),%a0 // Get the value of the PC
- move.l %a0,%d0 // Copy it to a data reg, d0 is VV??????
- swap %d0 // Now d0 is ????VV??
- and.w #0xff00,%d0 // Now d0 is ????VV00 (1)
- lsr.w #6,%d0 // Now d0.w contains the VBR table offset
- move.l VBR,%a0 // Get the address from VBR to a0
- move.l (%a0,%d0.w),%a0 // Fetch the vector
- move.l 4(%sp),%d0 // Restore d0
- move.l %a0,4(%sp) // Place target address to the stack
- move.l (%sp)+,%a0 // Restore a0, target address is on TOS
- ret // This will jump to the handler and
+ move.l %d0,-(%sp) // Save d0
+ move.l %a0,-(%sp) // Save a0
+ lea 0(%pc),%a0 // Get the value of the PC
+ move.l %a0,%d0 // Copy it to a data reg, d0 is VV??????
+ swap %d0 // Now d0 is ????VV??
+ and.w #0xff00,%d0 // Now d0 is ????VV00 (1)
+ lsr.w #6,%d0 // Now d0.w contains the VBR table offset
+ move.l VBR,%a0 // Get the address from VBR to a0
+ move.l (%a0,%d0.w),%a0 // Fetch the vector
+ move.l 4(%sp),%d0 // Restore d0
+ move.l %a0,4(%sp) // Place target address to the stack
+ move.l (%sp)+,%a0 // Restore a0, target address is on TOS
+ ret // This will jump to the handler and
// restore the stack
- (1) If 'myhandler' is guaranteed to be in the first 64K, e.g. just
+
+(1) If 'myhandler' is guaranteed to be in the first 64K, e.g. just
after the vector table then that insn is not needed.
-There are probably shorter ways to do this, but it I believe is enough
-to illustrate the trick. Optimisation is left as an exercise to the
-reader :-)
+There are probably shorter ways to do this, but it I believe is enough to
+illustrate the trick. Optimisation is left as an exercise to the reader :-)
Interrupt Levels
----------------
-Eight levels (0-7) of interrupt priorities are
-supported by MC68xxx family members with level seven (7) being
-the highest priority. Level zero (0) indicates that interrupts
-are fully enabled. Interrupt requests for interrupts with
-priorities less than or equal to the current interrupt mask
-level are ignored.
+Eight levels (0-7) of interrupt priorities are supported by MC68xxx family
+members with level seven (7) being the highest priority. Level zero (0)
+indicates that interrupts are fully enabled. Interrupt requests for interrupts
+with priorities less than or equal to the current interrupt mask level are
+ignored.
-Although RTEMS supports 256 interrupt levels, the
-MC68xxx family only supports eight. RTEMS interrupt levels 0
-through 7 directly correspond to MC68xxx interrupt levels. All
-other RTEMS interrupt levels are undefined and their behavior is
-unpredictable.
+Although RTEMS supports 256 interrupt levels, the MC68xxx family only supports
+eight. RTEMS interrupt levels 0 through 7 directly correspond to MC68xxx
+interrupt levels. All other RTEMS interrupt levels are undefined and their
+behavior is unpredictable.
Default Fatal Error Processing
==============================
The default fatal error handler for this architecture disables processor
-interrupts to level 7, places the error code in D0, and executes a``stop`` instruction to simulate a halt processor instruction.
+interrupts to level 7, places the error code in D0, and executes a ``stop``
+instruction to simulate a halt processor instruction.
Symmetric Multiprocessing
=========================
@@ -310,65 +302,55 @@ System Reset
------------
An RTEMS based application is initiated or re-initiated when the MC68020
-processor is reset. When the MC68020 is reset, the processor performs
-the following actions:
+processor is reset. When the MC68020 is reset, the processor performs the
+following actions:
-- The tracing bits of the status register are cleared to
- disable tracing.
+- The tracing bits of the status register are cleared to disable tracing.
-- The supervisor interrupt state is entered by setting the
- supervisor (S) bit and clearing the master/interrupt (M) bit of
- the status register.
+- The supervisor interrupt state is entered by setting the supervisor (S) bit
+ and clearing the master/interrupt (M) bit of the status register.
-- The interrupt mask of the status register is set to
- level 7 to effectively disable all maskable interrupts.
+- The interrupt mask of the status register is set to level 7 to effectively
+ disable all maskable interrupts.
- The vector base register (VBR) is set to zero.
-- The cache control register (CACR) is set to zero to
- disable and freeze the processor cache.
+- The cache control register (CACR) is set to zero to disable and freeze the
+ processor cache.
-- The interrupt stack pointer (ISP) is set to the value
- stored at vector 0 (bytes 0-3) of the exception vector table
- (EVT).
+- The interrupt stack pointer (ISP) is set to the value stored at vector 0
+ (bytes 0-3) of the exception vector table (EVT).
-- The program counter (PC) is set to the value stored at
- vector 1 (bytes 4-7) of the EVT.
+- The program counter (PC) is set to the value stored at vector 1 (bytes 4-7)
+ of the EVT.
-- The processor begins execution at the address stored in
- the PC.
+- The processor begins execution at the address stored in the PC.
Processor Initialization
------------------------
-The address of the application's initialization code should be stored in
-the first vector of the EVT which will allow the immediate vectoring to
-the application code. If the application requires that the VBR be some
-value besides zero, then it should be set to the required value at this
-point. All tasks share the same MC68020's VBR value. Because interrupts
-are enabled automatically by RTEMS as part of the context switch to the
-first task, the VBR MUST be set by either RTEMS of the BSP before this
-occurs ensure correct interrupt vectoring. If processor caching is
-to be utilized, then it should be enabled during the reset application
-initialization code.
-
-In addition to the requirements described in the
-Board Support Packages chapter of the Applications User's
-Manual for the reset code which is executed before the call to
-initialize executive, the MC68020 version has the following
+The address of the application's initialization code should be stored in the
+first vector of the EVT which will allow the immediate vectoring to the
+application code. If the application requires that the VBR be some value
+besides zero, then it should be set to the required value at this point. All
+tasks share the same MC68020's VBR value. Because interrupts are enabled
+automatically by RTEMS as part of the context switch to the first task, the VBR
+MUST be set by either RTEMS of the BSP before this occurs ensure correct
+interrupt vectoring. If processor caching is to be utilized, then it should be
+enabled during the reset application initialization code.
+
+In addition to the requirements described in the Board Support Packages chapter
+of the Applications User's Manual for the reset code which is executed before
+the call to initialize executive, the MC68020 version has the following
specific requirements:
-- Must leave the S bit of the status register set so that
- the MC68020 remains in the supervisor state.
+- Must leave the S bit of the status register set so that the MC68020 remains
+ in the supervisor state.
-- Must set the M bit of the status register to remove the
- MC68020 from the interrupt state.
+- Must set the M bit of the status register to remove the MC68020 from the
+ interrupt state.
-- Must set the master stack pointer (MSP) such that a
- minimum stack size of MINIMUM_STACK_SIZE bytes is provided for
- the initialize executive directive.
+- Must set the master stack pointer (MSP) such that a minimum stack size of
+ MINIMUM_STACK_SIZE bytes is provided for the initialize executive directive.
- Must initialize the MC68020's vector table.
-
-.. COMMENT: Copyright (c) 2014 embedded brains GmbH. All rights reserved.
-
diff --git a/cpu_supplement/mips.rst b/cpu_supplement/mips.rst
index c14c2e6..aca10ec 100644
--- a/cpu_supplement/mips.rst
+++ b/cpu_supplement/mips.rst
@@ -1,29 +1,25 @@
.. comment SPDX-License-Identifier: CC-BY-SA-4.0
+.. COMMENT: Copyright (c) 2014 embedded brains GmbH. All rights reserved.
+
MIPS Specific Information
#########################
-This chapter discusses the MIPS architecture dependencies
-in this port of RTEMS. The MIPS family has a wide variety
-of implementations by a wide range of vendors. Consequently,
-there are many, many CPU models within it.
+This chapter discusses the MIPS architecture dependencies in this port of
+RTEMS. The MIPS family has a wide variety of implementations by a wide range
+of vendors. Consequently, there are many, many CPU models within it.
**Architecture Documents**
IDT docs are online at http://www.idt.com/products/risc/Welcome.html
-For information on the XXX architecture, refer to the following documents
-available from VENDOR (:file:`http//www.XXX.com/`):
-
-- *XXX Family Reference, VENDOR, PART NUMBER*.
-
CPU Model Dependent Features
============================
-This section presents the set of features which vary
-across MIPS implementations and are of importance to RTEMS.
-The set of CPU model feature macros are defined in the file``cpukit/score/cpu/mips/mips.h`` based upon the particular CPU
-model specified on the compilation command line.
+This section presents the set of features which vary across MIPS
+implementations and are of importance to RTEMS. The set of CPU model feature
+macros are defined in the file ``cpukit/score/cpu/mips/mips.h`` based upon the
+particular CPU model specified on the compilation command line.
Another Optional Feature
------------------------
@@ -59,41 +55,36 @@ Memory Model
Flat Memory Model
-----------------
-The MIPS family supports a flat 32-bit address
-space with addresses ranging from 0x00000000 to 0xFFFFFFFF (4
-gigabytes). Each address is represented by a 32-bit value and
-is byte addressable. The address may be used to reference a
-single byte, word (2-bytes), or long word (4 bytes). Memory
-accesses within this address space are performed in big endian
-fashion by the processors in this family.
+The MIPS family supports a flat 32-bit address space with addresses ranging
+from 0x00000000 to 0xFFFFFFFF (4 gigabytes). Each address is represented by a
+32-bit value and is byte addressable. The address may be used to reference a
+single byte, word (2-bytes), or long word (4 bytes). Memory accesses within
+this address space are performed in big endian fashion by the processors in
+this family.
Some of the MIPS family members such as the support virtual memory and
-segmentation. RTEMS does not support virtual memory or
-segmentation on any of these family members.
+segmentation. RTEMS does not support virtual memory or segmentation on any of
+these family members.
Interrupt Processing
====================
-Although RTEMS hides many of the processor dependent
-details of interrupt processing, it is important to understand
-how the RTEMS interrupt manager is mapped onto the processor's
-unique architecture. Discussed in this chapter are the MIPS's
-interrupt response and control mechanisms as they pertain to
-RTEMS.
+Although RTEMS hides many of the processor dependent details of interrupt
+processing, it is important to understand how the RTEMS interrupt manager is
+mapped onto the processor's unique architecture. Discussed in this chapter are
+the MIPS's interrupt response and control mechanisms as they pertain to RTEMS.
Vectoring of an Interrupt Handler
---------------------------------
-Upon receipt of an interrupt the XXX family
-members with separate interrupt stacks automatically perform the
-following actions:
+Upon receipt of an interrupt the XXX family members with separate interrupt
+stacks automatically perform the following actions:
- TBD
-A nested interrupt is processed similarly by these
-CPU models with the exception that only a single ISF is placed
-on the interrupt stack and the current stack need not be
-switched.
+A nested interrupt is processed similarly by these CPU models with the
+exception that only a single ISF is placed on the interrupt stack and the
+current stack need not be switched.
Interrupt Levels
----------------
@@ -103,8 +94,9 @@ TBD
Default Fatal Error Processing
==============================
-The default fatal error handler for this target architecture disables
-processor interrupts, places the error code in *XXX*, and executes a``XXX`` instruction to simulate a halt processor instruction.
+The default fatal error handler for this target architecture disables processor
+interrupts, places the error code in *XXX*, and executes a``XXX`` instruction
+to simulate a halt processor instruction.
Symmetric Multiprocessing
=========================
@@ -122,9 +114,8 @@ Board Support Packages
System Reset
------------
-An RTEMS based application is initiated or
-re-initiated when the processor is reset. When the
-processor is reset, it performs the following actions:
+An RTEMS based application is initiated or re-initiated when the processor is
+reset. When the processor is reset, it performs the following actions:
- TBD
@@ -132,6 +123,3 @@ Processor Initialization
------------------------
TBD
-
-.. COMMENT: Copyright (c) 2014 embedded brains GmbH. All rights reserved.
-
diff --git a/cpu_supplement/openrisc_1000.rst b/cpu_supplement/openrisc_1000.rst
index cb4b9cc..c9d6127 100644
--- a/cpu_supplement/openrisc_1000.rst
+++ b/cpu_supplement/openrisc_1000.rst
@@ -1,21 +1,27 @@
.. comment SPDX-License-Identifier: CC-BY-SA-4.0
+.. COMMENT: COPYRIGHT (c) 1989-2007.
+.. COMMENT: On-Line Applications Research Corporation (OAR).
+.. COMMENT: All rights reserved.
+
OpenRISC 1000 Specific Information
##################################
-This chapter discusses the`OpenRISC 1000 architecture <http://opencores.org/or1k/Main_Page>`_
-dependencies in this port of RTEMS. There are many implementations
-for OpenRISC like or1200 and mor1kx. Currently RTEMS supports basic
-features that all implementations should have.
+This chapter discusses the`OpenRISC 1000 architecture
+http://opencores.org/or1k/Main_Page dependencies in this port of RTEMS. There
+are many implementations for OpenRISC like or1200 and mor1kx. Currently RTEMS
+supports basic features that all implementations should have.
**Architecture Documents**
-For information on the OpenRISC 1000 architecture refer to the`OpenRISC 1000 architecture manual <http://openrisc.github.io/or1k.html>`_.
+For information on the OpenRISC 1000 architecture refer to the`OpenRISC 1000
+architecture manual http://openrisc.github.io/or1k.html.
Calling Conventions
===================
-Please refer to the`Function Calling Sequence <http://openrisc.github.io/or1k.html#__RefHeading__504887_595890882>`_.
+Please refer to the`Function Calling Sequence
+http://openrisc.github.io/or1k.html#__RefHeading__504887_595890882.
Floating Point Unit
-------------------
@@ -68,16 +74,16 @@ There are only two levels: interrupts enabled and interrupts disabled.
Interrupt Stack
---------------
-The OpenRISC RTEMS port uses a dedicated software interrupt stack.
-The stack for interrupts is allocated during interrupt driver initialization.
-When an interrupt is entered, the _ISR_Handler routine is responsible for
-switching from the interrupted task stack to RTEMS software interrupt stack.
+The OpenRISC RTEMS port uses a dedicated software interrupt stack. The stack
+for interrupts is allocated during interrupt driver initialization. When an
+interrupt is entered, the _ISR_Handler routine is responsible for switching
+from the interrupted task stack to RTEMS software interrupt stack.
Default Fatal Error Processing
==============================
-The default fatal error handler for this architecture performs the
-following actions:
+The default fatal error handler for this architecture performs the following
+actions:
- disables operating system supported interrupts (IRQ),
@@ -89,10 +95,3 @@ Symmetric Multiprocessing
=========================
SMP is not supported.
-
-.. COMMENT: COPYRIGHT (c) 1989-2007.
-
-.. COMMENT: On-Line Applications Research Corporation (OAR).
-
-.. COMMENT: All rights reserved.
-
diff --git a/cpu_supplement/port.rst b/cpu_supplement/port.rst
index 12f9003..9ccd2f4 100644
--- a/cpu_supplement/port.rst
+++ b/cpu_supplement/port.rst
@@ -1,85 +1,84 @@
.. comment SPDX-License-Identifier: CC-BY-SA-4.0
+.. COMMENT: COPYRIGHT (c) 1988-2002.
+.. COMMENT: On-Line Applications Research Corporation (OAR).
+.. COMMENT: All rights reserved.
+
Port Specific Information
#########################
-This chaper provides a general description of the type of
-architecture specific information which is in each of
-the architecture specific chapters that follow. The outline
-of this chapter is identical to that of the architecture
-specific chapters.
+This chaper provides a general description of the type of architecture specific
+information which is in each of the architecture specific chapters that follow.
+The outline of this chapter is identical to that of the architecture specific
+chapters.
-In each of the architecture specific chapters, this
-introductory section will provide an overview of the
-architecture
+In each of the architecture specific chapters, this introductory section will
+provide an overview of the architecture:
**Architecture Documents**
-In each of the architecture specific chapters, this
-section will provide pointers on where to obtain
-documentation.
+In each of the architecture specific chapters, this section will provide
+pointers on where to obtain documentation.
CPU Model Dependent Features
============================
-Microprocessors are generally classified into families with a variety of
-CPU models or implementations within that family. Within a processor
-family, there is a high level of binary compatibility. This family
-may be based on either an architectural specification or on maintaining
-compatibility with a popular processor. Recent microprocessor families
-such as the SPARC or PowerPC are based on an architectural specification
-which is independent or any particular CPU model or implementation.
-Older families such as the Motorola 68000 and the Intel x86 evolved as the
-manufacturer strived to produce higher performance processor models which
-maintained binary compatibility with older models.
-
-RTEMS takes advantage of the similarity of the various models within a
-CPU family. Although the models do vary in significant ways, the high
-level of compatibility makes it possible to share the bulk of the CPU
-dependent executive code across the entire family. Each processor family
-supported by RTEMS has a list of features which vary between CPU models
-within a family. For example, the most common model dependent feature
-regardless of CPU family is the presence or absence of a floating point
-unit or coprocessor. When defining the list of features present on a
-particular CPU model, one simply notes that floating point hardware
-is or is not present and defines a single constant appropriately.
-Conditional compilation is utilized to include the appropriate source
-code for this CPU model's feature set. It is important to note that
-this means that RTEMS is thus compiled using the appropriate feature set
-and compilation flags optimal for this CPU model used. The alternative
-would be to generate a binary which would execute on all family members
-using only the features which were always present.
-
-The set of CPU model feature macros are defined in the file``cpukit/score/cpu/CPU/rtems/score/cpu.h`` based upon the GNU tools
-multilib variant that is appropriate for the particular CPU model defined
-on the compilation command line.
-
-In each of the architecture specific chapters, this section presents
-the set of features which vary across various implementations of the
-architecture that may be of importance to RTEMS application developers.
-
-The subsections will vary amongst the target architecture chapters as
-the specific features may vary. However, each port will include a few
-common features such as the CPU Model Name and presence of a hardware
-Floating Point Unit. The common features are described here.
+Microprocessors are generally classified into families with a variety of CPU
+models or implementations within that family. Within a processor family, there
+is a high level of binary compatibility. This family may be based on either an
+architectural specification or on maintaining compatibility with a popular
+processor. Recent microprocessor families such as the SPARC or PowerPC are
+based on an architectural specification which is independent or any particular
+CPU model or implementation. Older families such as the Motorola 68000 and the
+Intel x86 evolved as the manufacturer strived to produce higher performance
+processor models which maintained binary compatibility with older models.
+
+RTEMS takes advantage of the similarity of the various models within a CPU
+family. Although the models do vary in significant ways, the high level of
+compatibility makes it possible to share the bulk of the CPU dependent
+executive code across the entire family. Each processor family supported by
+RTEMS has a list of features which vary between CPU models within a family.
+For example, the most common model dependent feature regardless of CPU family
+is the presence or absence of a floating point unit or coprocessor. When
+defining the list of features present on a particular CPU model, one simply
+notes that floating point hardware is or is not present and defines a single
+constant appropriately. Conditional compilation is utilized to include the
+appropriate source code for this CPU model's feature set. It is important to
+note that this means that RTEMS is thus compiled using the appropriate feature
+set and compilation flags optimal for this CPU model used. The alternative
+would be to generate a binary which would execute on all family members using
+only the features which were always present.
+
+The set of CPU model feature macros are defined in the
+:file:`cpukit/score/cpu/CPU/rtems/score/cpu.h` based upon the GNU tools
+multilib variant that is appropriate for the particular CPU model defined on
+the compilation command line.
+
+In each of the architecture specific chapters, this section presents the set of
+features which vary across various implementations of the architecture that may
+be of importance to RTEMS application developers.
+
+The subsections will vary amongst the target architecture chapters as the
+specific features may vary. However, each port will include a few common
+features such as the CPU Model Name and presence of a hardware Floating Point
+Unit. The common features are described here.
CPU Model Name
--------------
-The macro ``CPU_MODEL_NAME`` is a string which designates
-the name of this CPU model. For example, for the MC68020
-processor model from the m68k architecture, this macro
-is set to the string "mc68020".
+The macro ``CPU_MODEL_NAME`` is a string which designates the name of this CPU
+model. For example, for the MC68020 processor model from the m68k
+architecture, this macro is set to the string "mc68020".
Floating Point Unit
-------------------
-In most architectures, the presence of a floating point unit is an option.
-It does not matter whether the hardware floating point support is
-incorporated on-chip or is an external coprocessor as long as it
-appears an FPU per the ISA. However, if a hardware FPU is not present,
-it is possible that the floating point emulation library for this
-CPU is not reentrant and thus context switched by RTEMS.
+In most architectures, the presence of a floating point unit is an option. It
+does not matter whether the hardware floating point support is incorporated
+on-chip or is an external coprocessor as long as it appears an FPU per the ISA.
+However, if a hardware FPU is not present, it is possible that the floating
+point emulation library for this CPU is not reentrant and thus context switched
+by RTEMS.
RTEMS provides two feature macros to indicate the FPU configuration:
@@ -87,13 +86,14 @@ RTEMS provides two feature macros to indicate the FPU configuration:
is set to TRUE to indicate that a hardware FPU is present.
- CPU_SOFTWARE_FP
- is set to TRUE to indicate that a hardware FPU is not present and that
- the FP software emulation will be context switched.
+ is set to TRUE to indicate that a hardware FPU is not present and that the FP
+ software emulation will be context switched.
Multilibs
=========
-Newlib and GCC provide several target libraries like the :file:`libc.a`,:file:`libm.a` and :file:`libgcc.a`. These libraries are artifacts of the GCC
+Newlib and GCC provide several target libraries like the :file:`libc.a`,
+:file:`libm.a` and :file:`libgcc.a`. These libraries are artifacts of the GCC
build process. Newlib is built together with GCC. To provide optimal support
for various chip derivatives and instruction set revisions multiple variants of
these libraries are available for each architecture. For example one set may
@@ -110,18 +110,19 @@ in the ``cpukit`` area of the RTEMS sources.
Invoking the GCC with the ``-print-multi-lib`` option lists the available
multilibs. Each line of the output describes one multilib variant. The
-default variant is denoted by ``.`` which is selected when no or
-contradicting GCC machine options are selected. The multilib selection for a
-target is specified by target makefile fragments (see file :file:`t-rtems` in
-the GCC sources and section`The Target Makefile Fragment <https://gcc.gnu.org/onlinedocs/gccint/Target-Fragment.html#Target-Fragment>`_
-in the `GCC Internals Manual <https://gcc.gnu.org/onlinedocs/gccint/>`_.
+default variant is denoted by ``.`` which is selected when no or contradicting
+GCC machine options are selected. The multilib selection for a target is
+specified by target makefile fragments (see file :file:`t-rtems` in the GCC
+sources and section *The Target Makefile Fragment*
+(https://gcc.gnu.org/onlinedocs/gccint/Target-Fragment.html#Target-Fragment)
+in the *GCC Internals Manual* (https://gcc.gnu.org/onlinedocs/gccint/).
Calling Conventions
===================
-Each high-level language compiler generates subroutine entry and exit
-code based upon a set of rules known as the compiler's calling convention.
-These rules address the following issues:
+Each high-level language compiler generates subroutine entry and exit code
+based upon a set of rules known as the compiler's calling convention. These
+rules address the following issues:
- register preservation and usage
@@ -129,202 +130,187 @@ These rules address the following issues:
- call and return mechanism
-A compiler's calling convention is of importance when
-interfacing to subroutines written in another language either
-assembly or high-level. Even when the high-level language and
-target processor are the same, different compilers may use
-different calling conventions. As a result, calling conventions
-are both processor and compiler dependent.
+A compiler's calling convention is of importance when interfacing to
+subroutines written in another language either assembly or high-level. Even
+when the high-level language and target processor are the same, different
+compilers may use different calling conventions. As a result, calling
+conventions are both processor and compiler dependent.
Calling Mechanism
-----------------
-In each of the architecture specific chapters, this subsection will
-describe the instruction(s) used to perform a *normal* subroutine
-invocation. All RTEMS directives are invoked as *normal* C language
-functions so it is important to the user application to understand the
-call and return mechanism.
+In each of the architecture specific chapters, this subsection will describe
+the instruction(s) used to perform a *normal* subroutine invocation. All RTEMS
+directives are invoked as *normal* C language functions so it is important to
+the user application to understand the call and return mechanism.
Register Usage
--------------
-In each of the architecture specific chapters, this subsection will
-detail the set of registers which are *NOT* preserved across subroutine
-invocations. The registers which are not preserved are assumed to be
-available for use as scratch registers. Therefore, the contents of these
-registers should not be assumed upon return from any RTEMS directive.
+In each of the architecture specific chapters, this subsection will detail the
+set of registers which are *NOT* preserved across subroutine invocations. The
+registers which are not preserved are assumed to be available for use as
+scratch registers. Therefore, the contents of these registers should not be
+assumed upon return from any RTEMS directive.
In some architectures, there may be a set of registers made available
-automatically as a side-effect of the subroutine invocation
-mechanism.
+automatically as a side-effect of the subroutine invocation mechanism.
Parameter Passing
-----------------
-In each of the architecture specific chapters, this subsection will
-describe the mechanism by which the parameters or arguments are passed
-by the caller to a subroutine. In some architectures, all parameters
-are passed on the stack while in others some are passed in registers.
+In each of the architecture specific chapters, this subsection will describe
+the mechanism by which the parameters or arguments are passed by the caller to
+a subroutine. In some architectures, all parameters are passed on the stack
+while in others some are passed in registers.
User-Provided Routines
----------------------
-All user-provided routines invoked by RTEMS, such as
-user extensions, device drivers, and MPCI routines, must also
-adhere to these calling conventions.
+All user-provided routines invoked by RTEMS, such as user extensions, device
+drivers, and MPCI routines, must also adhere to these calling conventions.
Memory Model
============
-A processor may support any combination of memory
-models ranging from pure physical addressing to complex demand
-paged virtual memory systems. RTEMS supports a flat memory
-model which ranges contiguously over the processor's allowable
-address space. RTEMS does not support segmentation or virtual
-memory of any kind. The appropriate memory model for RTEMS
-provided by the targeted processor and related characteristics
-of that model are described in this chapter.
+A processor may support any combination of memory models ranging from pure
+physical addressing to complex demand paged virtual memory systems. RTEMS
+supports a flat memory model which ranges contiguously over the processor's
+allowable address space. RTEMS does not support segmentation or virtual memory
+of any kind. The appropriate memory model for RTEMS provided by the targeted
+processor and related characteristics of that model are described in this
+chapter.
Flat Memory Model
-----------------
Most RTEMS target processors can be initialized to support a flat address
-space. Although the size of addresses varies between architectures, on
-most RTEMS targets, an address is 32-bits wide which defines addresses
-ranging from 0x00000000 to 0xFFFFFFFF (4 gigabytes). Each address is
-represented by a 32-bit value and is byte addressable. The address may be
-used to reference a single byte, word (2-bytes), or long word (4 bytes).
-Memory accesses within this address space may be performed in little or
-big endian fashion.
-
-On smaller CPU architectures supported by RTEMS, the address space
-may only be 20 or 24 bits wide.
-
-If the CPU model has support for virtual memory or segmentation, it is
-the responsibility of the Board Support Package (BSP) to initialize the
-MMU hardware to perform address translations which correspond to flat
-memory model.
-
-In each of the architecture specific chapters, this subsection will
-describe any architecture characteristics that differ from this general
-description.
+space. Although the size of addresses varies between architectures, on most
+RTEMS targets, an address is 32-bits wide which defines addresses ranging from
+0x00000000 to 0xFFFFFFFF (4 gigabytes). Each address is represented by a
+32-bit value and is byte addressable. The address may be used to reference a
+single byte, word (2-bytes), or long word (4 bytes). Memory accesses within
+this address space may be performed in little or big endian fashion.
+
+On smaller CPU architectures supported by RTEMS, the address space may only be
+20 or 24 bits wide.
+
+If the CPU model has support for virtual memory or segmentation, it is the
+responsibility of the Board Support Package (BSP) to initialize the MMU
+hardware to perform address translations which correspond to flat memory model.
+
+In each of the architecture specific chapters, this subsection will describe
+any architecture characteristics that differ from this general description.
Interrupt Processing
====================
-Different types of processors respond to the occurrence of an interrupt
-in its own unique fashion. In addition, each processor type provides
-a control mechanism to allow for the proper handling of an interrupt.
-The processor dependent response to the interrupt modifies the current
-execution state and results in a change in the execution stream. Most
-processors require that an interrupt handler utilize some special control
-mechanisms to return to the normal processing stream. Although RTEMS
-hides many of the processor dependent details of interrupt processing,
-it is important to understand how the RTEMS interrupt manager is mapped
-onto the processor's unique architecture.
-
-RTEMS supports a dedicated interrupt stack for all architectures.
-On architectures with hardware support for a dedicated interrupt stack,
-it will be initialized such that when an interrupt occurs, the processor
-automatically switches to this dedicated stack. On architectures without
-hardware support for a dedicated interrupt stack which is separate from
-those of the tasks, RTEMS will support switching to a dedicated stack
-for interrupt processing.
-
-Without a dedicated interrupt stack, every task in
-the system MUST have enough stack space to accommodate the worst
-case stack usage of that particular task and the interrupt
-service routines COMBINED. By supporting a dedicated interrupt
-stack, RTEMS significantly lowers the stack requirements for
-each task.
-
-A nested interrupt is processed similarly with the exception that since
-the CPU is already executing on the interrupt stack, there is no need
-to switch to the interrupt stack.
-
-In some configurations, RTEMS allocates the interrupt stack from the
-Workspace Area. The amount of memory allocated for the interrupt stack
-is user configured and based upon the ``confdefs.h`` parameter``CONFIGURE_INTERRUPT_STACK_SIZE``. This parameter is described
-in detail in the Configuring a System chapter of the User's Guide.
-On configurations in which RTEMS allocates the interrupt stack, during
-the initialization process, RTEMS will also install its interrupt stack.
-In other configurations, the interrupt stack is allocated and installed
-by the Board Support Package (BSP).
-
-In each of the architecture specific chapters, this section discesses
-the interrupt response and control mechanisms of the architecture as
-they pertain to RTEMS.
+Different types of processors respond to the occurrence of an interrupt in its
+own unique fashion. In addition, each processor type provides a control
+mechanism to allow for the proper handling of an interrupt. The processor
+dependent response to the interrupt modifies the current execution state and
+results in a change in the execution stream. Most processors require that an
+interrupt handler utilize some special control mechanisms to return to the
+normal processing stream. Although RTEMS hides many of the processor dependent
+details of interrupt processing, it is important to understand how the RTEMS
+interrupt manager is mapped onto the processor's unique architecture.
+
+RTEMS supports a dedicated interrupt stack for all architectures. On
+architectures with hardware support for a dedicated interrupt stack, it will be
+initialized such that when an interrupt occurs, the processor automatically
+switches to this dedicated stack. On architectures without hardware support
+for a dedicated interrupt stack which is separate from those of the tasks,
+RTEMS will support switching to a dedicated stack for interrupt processing.
+
+Without a dedicated interrupt stack, every task in the system MUST have enough
+stack space to accommodate the worst case stack usage of that particular task
+and the interrupt service routines COMBINED. By supporting a dedicated
+interrupt stack, RTEMS significantly lowers the stack requirements for each
+task.
+
+A nested interrupt is processed similarly with the exception that since the CPU
+is already executing on the interrupt stack, there is no need to switch to the
+interrupt stack.
+
+In some configurations, RTEMS allocates the interrupt stack from the Workspace
+Area. The amount of memory allocated for the interrupt stack is user
+configured and based upon the ``confdefs.h`` parameter
+``CONFIGURE_INTERRUPT_STACK_SIZE``. This parameter is described in detail in
+the Configuring a System chapter of the User's Guide. On configurations in
+which RTEMS allocates the interrupt stack, during the initialization process,
+RTEMS will also install its interrupt stack. In other configurations, the
+interrupt stack is allocated and installed by the Board Support Package (BSP).
+
+In each of the architecture specific chapters, this section discesses the
+interrupt response and control mechanisms of the architecture as they pertain
+to RTEMS.
Vectoring of an Interrupt Handler
---------------------------------
-In each of the architecture specific chapters, this subsection will
-describe the architecture specific details of the interrupt vectoring
-process. In particular, it should include a description of the
-Interrupt Stack Frame (ISF).
+In each of the architecture specific chapters, this subsection will describe
+the architecture specific details of the interrupt vectoring process. In
+particular, it should include a description of the Interrupt Stack Frame (ISF).
Interrupt Levels
----------------
-In each of the architecture specific chapters, this subsection will
-describe how the interrupt levels available on this particular architecture
-are mapped onto the 255 reserved in the task mode. The interrupt level
-value of zero (0) should always mean that interrupts are enabled.
+In each of the architecture specific chapters, this subsection will describe
+how the interrupt levels available on this particular architecture are mapped
+onto the 255 reserved in the task mode. The interrupt level value of zero (0)
+should always mean that interrupts are enabled.
-Any use of an interrupt level that is is not undefined on a particular
+Any use of an interrupt level that is is not undefined on a particular
architecture may result in behavior that is unpredictable.
Disabling of Interrupts by RTEMS
--------------------------------
-During the execution of directive calls, critical sections of code may
-be executed. When these sections are encountered, RTEMS disables all
-external interrupts before the execution of this section and restores
-them to the previous level upon completion of the section. RTEMS has
-been optimized to ensure that interrupts are disabled for the shortest
-number of instructions possible. Since the precise number of instructions
-and their execution time varies based upon target CPU family, CPU model,
-board memory speed, compiler version, and optimization level, it is
-not practical to provide the precise number for all possible RTEMS
-configurations.
-
-Historically, the measurements were made by hand analyzing and counting
-the execution time of instruction sequences during interrupt disable
-critical sections. For reference purposes, on a 16 Mhz Motorola
-MC68020, the maximum interrupt disable period was typically approximately
-ten (10) to thirteen (13) microseconds. This architecture was memory bound
-and had a slow bit scan instruction. In contrast, during the same
-period a 14 Mhz SPARC would have a worst case disable time of approximately
-two (2) to three (3) microseconds because it had a single cycle bit scan
-instruction and used fewer cycles for memory accesses.
-
-If you are interested in knowing the worst case execution time for
-a particular version of RTEMS, please contact OAR Corporation and
-we will be happy to product the results as a consulting service.
-
-Non-maskable interrupts (NMI) cannot be disabled, and
-ISRs which execute at this level MUST NEVER issue RTEMS system
-calls. If a directive is invoked, unpredictable results may
-occur due to the inability of RTEMS to protect its critical
-sections. However, ISRs that make no system calls may safely
-execute as non-maskable interrupts.
+During the execution of directive calls, critical sections of code may be
+executed. When these sections are encountered, RTEMS disables all external
+interrupts before the execution of this section and restores them to the
+previous level upon completion of the section. RTEMS has been optimized to
+ensure that interrupts are disabled for the shortest number of instructions
+possible. Since the precise number of instructions and their execution time
+varies based upon target CPU family, CPU model, board memory speed, compiler
+version, and optimization level, it is not practical to provide the precise
+number for all possible RTEMS configurations.
+
+Historically, the measurements were made by hand analyzing and counting the
+execution time of instruction sequences during interrupt disable critical
+sections. For reference purposes, on a 16 Mhz Motorola MC68020, the maximum
+interrupt disable period was typically approximately ten (10) to thirteen (13)
+microseconds. This architecture was memory bound and had a slow bit scan
+instruction. In contrast, during the same period a 14 Mhz SPARC would have a
+worst case disable time of approximately two (2) to three (3) microseconds
+because it had a single cycle bit scan instruction and used fewer cycles for
+memory accesses.
+
+If you are interested in knowing the worst case execution time for a particular
+version of RTEMS, please contact OAR Corporation and we will be happy to
+product the results as a consulting service.
+
+Non-maskable interrupts (NMI) cannot be disabled, and ISRs which execute at
+this level MUST NEVER issue RTEMS system calls. If a directive is invoked,
+unpredictable results may occur due to the inability of RTEMS to protect its
+critical sections. However, ISRs that make no system calls may safely execute
+as non-maskable interrupts.
Default Fatal Error Processing
==============================
Upon detection of a fatal error by either the application or RTEMS during
-initialization the ``rtems_fatal_error_occurred`` directive supplied
-by the Fatal Error Manager is invoked. The Fatal Error Manager will
-invoke the user-supplied fatal error handlers. If no user-supplied
-handlers are configured or all of them return without taking action to
-shutdown the processor or reset, a default fatal error handler is invoked.
+initialization the ``rtems_fatal_error_occurred`` directive supplied by the
+Fatal Error Manager is invoked. The Fatal Error Manager will invoke the
+user-supplied fatal error handlers. If no user-supplied handlers are
+configured or all of them return without taking action to shutdown the
+processor or reset, a default fatal error handler is invoked.
Most of the action performed as part of processing the fatal error are
-described in detail in the Fatal Error Manager chapter in the User's
-Guide. However, the if no user provided extension or BSP specific fatal
-error handler takes action, the final default action is to invoke a
-CPU architecture specific function. Typically this function disables
-interrupts and halts the processor.
+described in detail in the Fatal Error Manager chapter in the User's Guide.
+However, the if no user provided extension or BSP specific fatal error handler
+takes action, the final default action is to invoke a CPU architecture specific
+function. Typically this function disables interrupts and halts the processor.
In each of the architecture specific chapters, this describes the precise
operations of the default CPU specific fatal error handler.
@@ -340,34 +326,38 @@ Thread-Local Storage
In order to support thread-local storage (TLS) the CPU port must implement the
facilities mandated by the application binary interface (ABI) of the CPU
-architecture. The CPU port must initialize the TLS area in the``_CPU_Context_Initialize()`` function. There are support functions available
+architecture. The CPU port must initialize the TLS area in the
+``_CPU_Context_Initialize()`` function. There are support functions available
via ``#include <rtems/score/tls.h>`` which implement Variants I and II
according to Ulrich Drepper, *ELF Handling For Thread-Local Storage*.
``_TLS_TCB_at_area_begin_initialize()``
- Uses Variant I, TLS offsets emitted by linker takes the TCB into account. For
- a reference implementation see :file:`cpukit/score/cpu/arm/cpu.c`.
+ Uses Variant I, TLS offsets emitted by linker takes the TCB into account.
+ For a reference implementation see :file:`cpukit/score/cpu/arm/cpu.c`.
``_TLS_TCB_before_TLS_block_initialize()``
Uses Variant I, TLS offsets emitted by linker neglects the TCB. For a
- reference implementation see:file:`c/src/lib/libcpu/powerpc/new-exceptions/cpu.c`.
+ reference implementation see
+ :file:`c/src/lib/libcpu/powerpc/new-exceptions/cpu.c`.
``_TLS_TCB_after_TLS_block_initialize()``
- Uses Variant II. For a reference implementation see:file:`cpukit/score/cpu/sparc/cpu.c`.
+ Uses Variant II. For a reference implementation see
+ :file:`cpukit/score/cpu/sparc/cpu.c`.
The board support package (BSP) must provide the following sections and symbols
in its linker command file:
-.. code:: c
+
+.. code-block:: c
.tdata : {
- _TLS_Data_begin = .;
- \*(.tdata .tdata.* .gnu.linkonce.td.*)
- _TLS_Data_end = .;
+ _TLS_Data_begin = .;
+ *(.tdata .tdata.* .gnu.linkonce.td.*)
+ _TLS_Data_end = .;
}
.tbss : {
- _TLS_BSS_begin = .;
- \*(.tbss .tbss.* .gnu.linkonce.tb.*) \*(.tcommon)
- _TLS_BSS_end = .;
+ _TLS_BSS_begin = .;
+ *(.tbss .tbss.* .gnu.linkonce.tb.*) *(.tcommon)
+ _TLS_BSS_end = .;
}
_TLS_Data_size = _TLS_Data_end - _TLS_Data_begin;
_TLS_Data_begin = _TLS_Data_size != 0 ? _TLS_Data_begin : _TLS_BSS_begin;
@@ -383,11 +373,13 @@ The CPU support must implement the CPU counter interface. A CPU counter is
some free-running counter. It ticks usually with a frequency close to the CPU
or system bus clock. On some architectures the actual implementation is board
support package dependent. The CPU counter is used for profiling of low-level
-functions. It is also used to implement two busy wait functions``rtems_counter_delay_ticks()`` and ``rtems_counter_delay_nanoseconds()``
-which may be used in device drivers. It may be also used as an entropy source
-for random number generators.
+functions. It is also used to implement two busy wait functions
+``rtems_counter_delay_ticks()`` and ``rtems_counter_delay_nanoseconds()`` which
+may be used in device drivers. It may be also used as an entropy source for
+random number generators.
-The CPU counter interface uses a CPU port specific unsigned integer type``CPU_Counter_ticks`` to represent CPU counter values. The CPU port must
+The CPU counter interface uses a CPU port specific unsigned integer type
+``CPU_Counter_ticks`` to represent CPU counter values. The CPU port must
provide the following two functions
- ``_CPU_Counter_read()`` to read the current CPU counter value, and
@@ -400,37 +392,31 @@ Interrupt Profiling
The RTEMS profiling needs support by the CPU port for the interrupt entry and
exit times. In case profiling is enabled via the RTEMS build configuration
-option ``--enable-profiling`` (in this case the pre-processor symbol``RTEMS_PROFILING`` is defined) the CPU port may provide data for the
-interrupt entry and exit times of the outer-most interrupt. The CPU port can
-feed interrupt entry and exit times with the``_Profiling_Outer_most_interrupt_entry_and_exit()`` function
-(``#include <rtems/score/profiling.h>``). For an example please have a look
-at ``cpukit/score/cpu/arm/arm_exc_interrupt.S``.
+option ``--enable-profiling`` (in this case the pre-processor symbol
+``RTEMS_PROFILING`` is defined) the CPU port may provide data for the interrupt
+entry and exit times of the outer-most interrupt. The CPU port can feed
+interrupt entry and exit times with the
+``_Profiling_Outer_most_interrupt_entry_and_exit()`` function (``#include
+<rtems/score/profiling.h>``). For an example please have a look at
+:file:`cpukit/score/cpu/arm/arm_exc_interrupt.S`.
Board Support Packages
======================
-An RTEMS Board Support Package (BSP) must be designed to support a
-particular processor model and target board combination.
+An RTEMS Board Support Package (BSP) must be designed to support a particular
+processor model and target board combination.
-In each of the architecture specific chapters, this section will present
-a discussion of architecture specific BSP issues. For more information
-on developing a BSP, refer to BSP and Device Driver Development Guide
-and the chapter titled Board Support Packages in the RTEMS
-Applications User's Guide.
+In each of the architecture specific chapters, this section will present a
+discussion of architecture specific BSP issues. For more information on
+developing a BSP, refer to BSP and Device Driver Development Guide and the
+chapter titled Board Support Packages in the RTEMS Applications User's Guide.
System Reset
------------
-An RTEMS based application is initiated or re-initiated when the processor
-is reset or transfer is passed to it from a boot monitor or ROM monitor.
-
-In each of the architecture specific chapters, this subsection describes
-the actions that the BSP must tak assuming the application gets control
-when the microprocessor is reset.
-
-.. COMMENT: COPYRIGHT (c) 1988-2002.
-
-.. COMMENT: On-Line Applications Research Corporation (OAR).
-
-.. COMMENT: All rights reserved.
+An RTEMS based application is initiated or re-initiated when the processor is
+reset or transfer is passed to it from a boot monitor or ROM monitor.
+In each of the architecture specific chapters, this subsection describes the
+actions that the BSP must tak assuming the application gets control when the
+microprocessor is reset.
diff --git a/cpu_supplement/powerpc.rst b/cpu_supplement/powerpc.rst
index 8ce7a58..5204ebc 100644
--- a/cpu_supplement/powerpc.rst
+++ b/cpu_supplement/powerpc.rst
@@ -1,23 +1,25 @@
.. comment SPDX-License-Identifier: CC-BY-SA-4.0
+.. COMMENT: COPYRIGHT (c) 1988-2002.
+.. COMMENT: On-Line Applications Research Corporation (OAR).
+.. COMMENT: All rights reserved.
+
PowerPC Specific Information
############################
-This chapter discusses the PowerPC architecture dependencies
-in this port of RTEMS. The PowerPC family has a wide variety
-of implementations by a range of vendors. Consequently,
-there are many, many CPU models within it.
+This chapter discusses the PowerPC architecture dependencies in this port of
+RTEMS. The PowerPC family has a wide variety of implementations by a range of
+vendors. Consequently, there are many, many CPU models within it.
-It is highly recommended that the PowerPC RTEMS
-application developer obtain and become familiar with the
-documentation for the processor being used as well as the
-specification for the revision of the PowerPC architecture which
+It is highly recommended that the PowerPC RTEMS application developer obtain
+and become familiar with the documentation for the processor being used as well
+as the specification for the revision of the PowerPC architecture which
corresponds to that processor.
**PowerPC Architecture Documents**
-For information on the PowerPC architecture, refer to
-the following documents available from Motorola and IBM:
+For information on the PowerPC architecture, refer to the following documents
+available from Motorola and IBM:
- *PowerPC Microprocessor Family: The Programming Environment*
(Motorola Document MPRPPCFPE-01).
@@ -42,53 +44,52 @@ the following documents available from Motorola and IBM:
- *PowerPC MPC821 Portable Systems Microprocessor User's Manual*
(Motorola Document MPC821UM/AD).
-- *PowerQUICC MPC860 User's Manual* (Motorola Document MPC860UM/AD).
+- *PowerQUICC MPC860 User's Manual*
+ (Motorola Document MPC860UM/AD).
-Motorola maintains an on-line electronic library for the PowerPC
-at the following URL:
+Motorola maintains an on-line electronic library for the PowerPC at the
+following URL:
- http://www.mot.com/powerpc/library/library.html
-This site has a a wealth of information and examples. Many of the
-manuals are available from that site in electronic format.
+This site has a a wealth of information and examples. Many of the manuals are
+available from that site in electronic format.
**PowerPC Processor Simulator Information**
-PSIM is a program which emulates the Instruction Set Architecture
-of the PowerPC microprocessor family. It is reely available in source
-code form under the terms of the GNU General Public License (version
-2 or later). PSIM can be integrated with the GNU Debugger (gdb) to
-execute and debug PowerPC executables on non-PowerPC hosts. PSIM
-supports the addition of user provided device models which can be
-used to allow one to develop and debug embedded applications using
-the simulator.
+PSIM is a program which emulates the Instruction Set Architecture of the
+PowerPC microprocessor family. It is reely available in source code form under
+the terms of the GNU General Public License (version 2 or later). PSIM can be
+integrated with the GNU Debugger (gdb) to execute and debug PowerPC executables
+on non-PowerPC hosts. PSIM supports the addition of user provided device
+models which can be used to allow one to develop and debug embedded
+applications using the simulator.
-The latest version of PSIM is included in GDB and enabled on pre-built
-binaries provided by the RTEMS Project.
+The latest version of PSIM is included in GDB and enabled on pre-built binaries
+provided by the RTEMS Project.
CPU Model Dependent Features
============================
-This section presents the set of features which vary
-across PowerPC implementations and are of importance to RTEMS.
-The set of CPU model feature macros are defined in the file``cpukit/score/cpu/powerpc/powerpc.h`` based upon the particular CPU
-model specified on the compilation command line.
+This section presents the set of features which vary across PowerPC
+implementations and are of importance to RTEMS. The set of CPU model feature
+macros are defined in the file ``cpukit/score/cpu/powerpc/powerpc.h`` based
+upon the particular CPU model specified on the compilation command line.
Alignment
---------
The macro PPC_ALIGNMENT is set to the PowerPC model's worst case alignment
-requirement for data types on a byte boundary. This value is used
-to derive the alignment restrictions for memory allocated from
-regions and partitions.
+requirement for data types on a byte boundary. This value is used to derive
+the alignment restrictions for memory allocated from regions and partitions.
Cache Alignment
---------------
-The macro PPC_CACHE_ALIGNMENT is set to the line size of the cache. It is
-used to align the entry point of critical routines so that as much code
-as possible can be retrieved with the initial read into cache. This
-is done for the interrupt handler as well as the context switch routines.
+The macro PPC_CACHE_ALIGNMENT is set to the line size of the cache. It is used
+to align the entry point of critical routines so that as much code as possible
+can be retrieved with the initial read into cache. This is done for the
+interrupt handler as well as the context switch routines.
In addition, the "shortcut" data structure used by the PowerPC implementation
to ease access to data elements frequently accessed by RTEMS routines
@@ -97,31 +98,31 @@ implemented in assembly language is aligned using this value.
Maximum Interrupts
------------------
-The macro PPC_INTERRUPT_MAX is set to the number of exception sources
-supported by this PowerPC model.
+The macro PPC_INTERRUPT_MAX is set to the number of exception sources supported
+by this PowerPC model.
Has Double Precision Floating Point
-----------------------------------
-The macro PPC_HAS_DOUBLE is set to 1 to indicate that the PowerPC model
-has support for double precision floating point numbers. This is
-important because the floating point registers need only be four bytes
-wide (not eight) if double precision is not supported.
+The macro PPC_HAS_DOUBLE is set to 1 to indicate that the PowerPC model has
+support for double precision floating point numbers. This is important because
+the floating point registers need only be four bytes wide (not eight) if double
+precision is not supported.
Critical Interrupts
-------------------
-The macro PPC_HAS_RFCI is set to 1 to indicate that the PowerPC model
-has the Critical Interrupt capability as defined by the IBM 403 models.
+The macro PPC_HAS_RFCI is set to 1 to indicate that the PowerPC model has the
+Critical Interrupt capability as defined by the IBM 403 models.
Use Multiword Load/Store Instructions
-------------------------------------
The macro PPC_USE_MULTIPLE is set to 1 to indicate that multiword load and
-store instructions should be used to perform context switch operations.
-The relative efficiency of multiword load and store instructions versus
-an equivalent set of single word load and store instructions varies based
-upon the PowerPC model.
+store instructions should be used to perform context switch operations. The
+relative efficiency of multiword load and store instructions versus an
+equivalent set of single word load and store instructions varies based upon the
+PowerPC model.
Instruction Cache Size
----------------------
@@ -136,36 +137,35 @@ The macro PPC_D_CACHE is set to the size in bytes of the data cache.
Debug Model
-----------
-The macro PPC_DEBUG_MODEL is set to indicate the debug support features
-present in this CPU model. The following debug support feature sets
-are currently supported:
+The macro PPC_DEBUG_MODEL is set to indicate the debug support features present
+in this CPU model. The following debug support feature sets are currently
+supported:
*``PPC_DEBUG_MODEL_STANDARD``*
- indicates that the single-step trace enable (SE) and branch trace
- enable (BE) bits in the MSR are supported by this CPU model.
+ indicates that the single-step trace enable (SE) and branch trace enable
+ (BE) bits in the MSR are supported by this CPU model.
*``PPC_DEBUG_MODEL_SINGLE_STEP_ONLY``*
- indicates that only the single-step trace enable (SE) bit in the MSR
- is supported by this CPU model.
+ indicates that only the single-step trace enable (SE) bit in the MSR is
+ supported by this CPU model.
*``PPC_DEBUG_MODEL_IBM4xx``*
indicates that the debug exception enable (DE) bit in the MSR is supported
- by this CPU model. At this time, this particular debug feature set
- has only been seen in the IBM 4xx series.
+ by this CPU model. At this time, this particular debug feature set has
+ only been seen in the IBM 4xx series.
Low Power Model
~~~~~~~~~~~~~~~
-The macro PPC_LOW_POWER_MODE is set to indicate the low power model
-supported by this CPU model. The following low power modes are currently
-supported.
+The macro PPC_LOW_POWER_MODE is set to indicate the low power model supported
+by this CPU model. The following low power modes are currently supported.
*``PPC_LOW_POWER_MODE_NONE``*
indicates that this CPU model has no low power mode support.
*``PPC_LOW_POWER_MODE_STANDARD``*
- indicates that this CPU model follows the low power model defined for
- the PPC603e.
+ indicates that this CPU model follows the low power model defined for the
+ PPC603e.
Multilibs
=========
@@ -215,15 +215,14 @@ The following multilibs are available:
Calling Conventions
===================
-RTEMS supports the Embedded Application Binary Interface (EABI)
-calling convention. Documentation for EABI is available by sending
-a message with a subject line of "EABI" to eabi@goth.sis.mot.com.
+RTEMS supports the Embedded Application Binary Interface (EABI) calling
+convention. Documentation for EABI is available by sending a message with a
+subject line of "EABI" to eabi@goth.sis.mot.com.
Programming Model
-----------------
-This section discusses the programming model for the
-PowerPC architecture.
+This section discusses the programming model for the PowerPC architecture.
Non-Floating Point Registers
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -235,116 +234,109 @@ register is sixty-four bits wide.
These registers are referred to as ``gpr0`` to ``gpr31``.
-Some of the registers serve defined roles in the EABI programming model.
-The following table describes the role of each of these registers:
-.. code:: c
-
- +---------------+----------------+------------------------------+
- | Register Name | Alternate Name | Description |
- +---------------+----------------+------------------------------+
- | r1 | sp | stack pointer |
- +---------------+----------------+------------------------------+
- | | | global pointer to the Small |
- | r2 | na | Constant Area (SDA2) |
- +---------------+----------------+------------------------------+
- | r3 - r12 | na | parameter and result passing |
- +---------------+----------------+------------------------------+
- | | | global pointer to the Small |
- | r13 | na | Data Area (SDA) |
- +---------------+----------------+------------------------------+
+Some of the registers serve defined roles in the EABI programming model. The
+following table describes the role of each of these registers:
+
++---------------+----------------+------------------------------+
+| Register Name | Alternate Name | Description |
++---------------+----------------+------------------------------+
+| r1 | sp | stack pointer |
++---------------+----------------+------------------------------+
+| | | global pointer to the Small |
+| r2 | na | Constant Area (SDA2) |
++---------------+----------------+------------------------------+
+| r3 - r12 | na | parameter and result passing |
++---------------+----------------+------------------------------+
+| | | global pointer to the Small |
+| r13 | na | Data Area (SDA) |
++---------------+----------------+------------------------------+
Floating Point Registers
~~~~~~~~~~~~~~~~~~~~~~~~
-The PowerPC architecture includes thirty-two, sixty-four bit
-floating point registers. All PowerPC floating point instructions
-interpret these registers as 32 double precision floating point registers,
-regardless of whether the processor has 64-bit or 32-bit implementation.
+The PowerPC architecture includes thirty-two, sixty-four bit floating point
+registers. All PowerPC floating point instructions interpret these registers
+as 32 double precision floating point registers, regardless of whether the
+processor has 64-bit or 32-bit implementation.
-The floating point status and control register (fpscr) records exceptions
-and the type of result generated by floating-point operations.
-Additionally, it controls the rounding mode of operations and allows the
-reporting of floating exceptions to be enabled or disabled.
+The floating point status and control register (fpscr) records exceptions and
+the type of result generated by floating-point operations. Additionally, it
+controls the rounding mode of operations and allows the reporting of floating
+exceptions to be enabled or disabled.
Special Registers
~~~~~~~~~~~~~~~~~
-The PowerPC architecture includes a number of special registers
-which are critical to the programming model:
+The PowerPC architecture includes a number of special registers which are
+critical to the programming model:
*Machine State Register*
The MSR contains the processor mode, power management mode, endian mode,
exception information, privilege level, floating point available and
- floating point excepiton mode, address translation information and
- the exception prefix.
+ floating point excepiton mode, address translation information and the
+ exception prefix.
*Link Register*
The LR contains the return address after a function call. This register
- must be saved before a subsequent subroutine call can be made. The
- use of this register is discussed further in the *Call and Return
- Mechanism* section below.
+ must be saved before a subsequent subroutine call can be made. The use of
+ this register is discussed further in the *Call and Return Mechanism*
+ section below.
*Count Register*
- The CTR contains the iteration variable for some loops. It may also be used
- for indirect function calls and jumps.
+ The CTR contains the iteration variable for some loops. It may also be
+ used for indirect function calls and jumps.
Call and Return Mechanism
-------------------------
-The PowerPC architecture supports a simple yet effective call
-and return mechanism. A subroutine is invoked
-via the "branch and link" (``bl``) and
-"brank and link absolute" (``bla``)
-instructions. This instructions place the return address
-in the Link Register (LR). The callee returns to the caller by
-executing a "branch unconditional to the link register" (``blr``)
-instruction. Thus the callee returns to the caller via a jump
-to the return address which is stored in the LR.
-
-The previous contents of the LR are not automatically saved
-by either the ``bl`` or ``bla``. It is the responsibility
-of the callee to save the contents of the LR before invoking
-another subroutine. If the callee invokes another subroutine,
-it must restore the LR before executing the ``blr`` instruction
-to return to the caller.
-
-It is important to note that the PowerPC subroutine
-call and return mechanism does not automatically save and
-restore any registers.
-
-The LR may be accessed as special purpose register 8 (``SPR8``) using the
-"move from special register" (``mfspr``) and
-"move to special register" (``mtspr``) instructions.
+The PowerPC architecture supports a simple yet effective call and return
+mechanism. A subroutine is invoked via the "branch and link" (``bl``) and
+"brank and link absolute" (``bla``) instructions. This instructions place the
+return address in the Link Register (LR). The callee returns to the caller by
+executing a "branch unconditional to the link register" (``blr``) instruction.
+Thus the callee returns to the caller via a jump to the return address which is
+stored in the LR.
+
+The previous contents of the LR are not automatically saved by either the
+``bl`` or ``bla``. It is the responsibility of the callee to save the contents
+of the LR before invoking another subroutine. If the callee invokes another
+subroutine, it must restore the LR before executing the ``blr`` instruction to
+return to the caller.
+
+It is important to note that the PowerPC subroutine call and return mechanism
+does not automatically save and restore any registers.
+
+The LR may be accessed as special purpose register 8 (``SPR8``) using the "move
+from special register" (``mfspr``) and "move to special register" (``mtspr``)
+instructions.
Calling Mechanism
-----------------
-All RTEMS directives are invoked using the regular
-PowerPC EABI calling convention via the ``bl`` or``bla`` instructions.
+All RTEMS directives are invoked using the regular PowerPC EABI calling
+convention via the ``bl`` or``bla`` instructions.
Register Usage
--------------
-As discussed above, the call instruction does not
-automatically save any registers. It is the responsibility
-of the callee to save and restore any registers which must be preserved
-across subroutine calls. The callee is responsible for saving
-callee-preserved registers to the program stack and restoring them
-before returning to the caller.
+As discussed above, the call instruction does not automatically save any
+registers. It is the responsibility of the callee to save and restore any
+registers which must be preserved across subroutine calls. The callee is
+responsible for saving callee-preserved registers to the program stack and
+restoring them before returning to the caller.
Parameter Passing
-----------------
-RTEMS assumes that arguments are placed in the
-general purpose registers with the first argument in
-register 3 (``r3``), the second argument in general purpose
-register 4 (``r4``), and so forth until the seventh
-argument is in general purpose register 10 (``r10``).
-If there are more than seven arguments, then subsequent arguments
-are placed on the program stack. The following pseudo-code
-illustrates the typical sequence used to call a RTEMS directive
+RTEMS assumes that arguments are placed in the general purpose registers with
+the first argument in register 3 (``r3``), the second argument in general
+purpose register 4 (``r4``), and so forth until the seventh argument is in
+general purpose register 10 (``r10``). If there are more than seven arguments,
+then subsequent arguments are placed on the program stack. The following
+pseudo-code illustrates the typical sequence used to call a RTEMS directive
with three (3) arguments:
-.. code:: c
+
+.. code-block:: c
load third argument into r5
load second argument into r4
@@ -357,95 +349,80 @@ Memory Model
Flat Memory Model
-----------------
-The PowerPC architecture supports a variety of memory models.
-RTEMS supports the PowerPC using a flat memory model with
-paging disabled. In this mode, the PowerPC automatically
-converts every address from a logical to a physical address
-each time it is used. The PowerPC uses information provided
-in the Block Address Translation (BAT) to convert these addresses.
-
-Implementations of the PowerPC architecture may be thirty-two or sixty-four bit.
-The PowerPC architecture supports a flat thirty-two or sixty-four bit address
-space with addresses ranging from 0x00000000 to 0xFFFFFFFF (4
-gigabytes) in thirty-two bit implementations or to 0xFFFFFFFFFFFFFFFF
-in sixty-four bit implementations. Each address is represented
-by either a thirty-two bit or sixty-four bit value and is byte addressable.
-The address may be used to reference a single byte, half-word
-(2-bytes), word (4 bytes), or in sixty-four bit implementations a
-doubleword (8 bytes). Memory accesses within the address space are
-performed in big or little endian fashion by the PowerPC based
-upon the current setting of the Little-endian mode enable bit (LE)
-in the Machine State Register (MSR). While the processor is in
-big endian mode, memory accesses which are not properly aligned
-generate an "alignment exception" (vector offset 0x00600). In
-little endian mode, the PowerPC architecture does not require
-the processor to generate alignment exceptions.
-
-The following table lists the alignment requirements for a variety
-of data accesses:
-
-.. code:: c
-
- +--------------+-----------------------+
- | Data Type | Alignment Requirement |
- +--------------+-----------------------+
- | byte | 1 |
- | half-word | 2 |
- | word | 4 |
- | doubleword | 8 |
- +--------------+-----------------------+
-
-Doubleword load and store operations are only available in
-PowerPC CPU models which are sixty-four bit implementations.
-
-RTEMS does not directly support any PowerPC Memory Management
-Units, therefore, virtual memory or segmentation systems
-involving the PowerPC are not supported.
-
-.. COMMENT: COPYRIGHT (c) 1989-2007.
-
-.. COMMENT: On-Line Applications Research Corporation (OAR).
-
-.. COMMENT: All rights reserved.
+The PowerPC architecture supports a variety of memory models. RTEMS supports
+the PowerPC using a flat memory model with paging disabled. In this mode, the
+PowerPC automatically converts every address from a logical to a physical
+address each time it is used. The PowerPC uses information provided in the
+Block Address Translation (BAT) to convert these addresses.
+
+Implementations of the PowerPC architecture may be thirty-two or sixty-four
+bit. The PowerPC architecture supports a flat thirty-two or sixty-four bit
+address space with addresses ranging from 0x00000000 to 0xFFFFFFFF (4
+gigabytes) in thirty-two bit implementations or to 0xFFFFFFFFFFFFFFFF in
+sixty-four bit implementations. Each address is represented by either a
+thirty-two bit or sixty-four bit value and is byte addressable. The address
+may be used to reference a single byte, half-word (2-bytes), word (4 bytes), or
+in sixty-four bit implementations a doubleword (8 bytes). Memory accesses
+within the address space are performed in big or little endian fashion by the
+PowerPC based upon the current setting of the Little-endian mode enable bit
+(LE) in the Machine State Register (MSR). While the processor is in big endian
+mode, memory accesses which are not properly aligned generate an "alignment
+exception" (vector offset 0x00600). In little endian mode, the PowerPC
+architecture does not require the processor to generate alignment exceptions.
+
+The following table lists the alignment requirements for a variety of data
+accesses:
+
++--------------+-----------------------+
+| Data Type | Alignment Requirement |
++--------------+-----------------------+
+| byte | 1 |
+| half-word | 2 |
+| word | 4 |
+| doubleword | 8 |
++--------------+-----------------------+
+
+Doubleword load and store operations are only available in PowerPC CPU models
+which are sixty-four bit implementations.
+
+RTEMS does not directly support any PowerPC Memory Management Units, therefore,
+virtual memory or segmentation systems involving the PowerPC are not supported.
Interrupt Processing
====================
-Although RTEMS hides many of the processor dependent
-details of interrupt processing, it is important to understand
-how the RTEMS interrupt manager is mapped onto the processor's
-unique architecture. Discussed in this chapter are the PowerPC's
-interrupt response and control mechanisms as they pertain to
+Although RTEMS hides many of the processor dependent details of interrupt
+processing, it is important to understand how the RTEMS interrupt manager is
+mapped onto the processor's unique architecture. Discussed in this chapter are
+the PowerPC's interrupt response and control mechanisms as they pertain to
RTEMS.
-RTEMS and associated documentation uses the terms interrupt and vector.
-In the PowerPC architecture, these terms correspond to exception and
-exception handler, respectively. The terms will be used interchangeably
-in this manual.
+RTEMS and associated documentation uses the terms interrupt and vector. In the
+PowerPC architecture, these terms correspond to exception and exception
+handler, respectively. The terms will be used interchangeably in this manual.
Synchronous Versus Asynchronous Exceptions
------------------------------------------
-In the PowerPC architecture exceptions can be either precise or
-imprecise and either synchronous or asynchronous. Asynchronous
-exceptions occur when an external event interrupts the processor.
-Synchronous exceptions are caused by the actions of an
-instruction. During an exception SRR0 is used to calculate where
-instruction processing should resume. All instructions prior to
-the resume instruction will have completed execution. SRR1 is used to
-store the machine status.
-
-There are two asynchronous nonmaskable, highest-priority exceptions
-system reset and machine check. There are two asynchrononous maskable
-low-priority exceptions external interrupt and decrementer. Nonmaskable
-execptions are never delayed, therefore if two nonmaskable, asynchronous
-exceptions occur in immediate succession, the state information saved by
-the first exception may be overwritten when the subsequent exception occurs.
-
-The PowerPC arcitecure defines one imprecise exception, the imprecise
-floating point enabled exception. All other synchronous exceptions are
-precise. The synchronization occuring during asynchronous precise
-exceptions conforms to the requirements for context synchronization.
+In the PowerPC architecture exceptions can be either precise or imprecise and
+either synchronous or asynchronous. Asynchronous exceptions occur when an
+external event interrupts the processor. Synchronous exceptions are caused by
+the actions of an instruction. During an exception SRR0 is used to calculate
+where instruction processing should resume. All instructions prior to the
+resume instruction will have completed execution. SRR1 is used to store the
+machine status.
+
+There are two asynchronous nonmaskable, highest-priority exceptions system
+reset and machine check. There are two asynchrononous maskable low-priority
+exceptions external interrupt and decrementer. Nonmaskable execptions are
+never delayed, therefore if two nonmaskable, asynchronous exceptions occur in
+immediate succession, the state information saved by the first exception may be
+overwritten when the subsequent exception occurs.
+
+The PowerPC arcitecure defines one imprecise exception, the imprecise floating
+point enabled exception. All other synchronous exceptions are precise. The
+synchronization occuring during asynchronous precise exceptions conforms to the
+requirements for context synchronization.
Vectoring of Interrupt Handler
------------------------------
@@ -455,67 +432,61 @@ performs the following actions:
- an instruction address is loaded into SRR0
-- bits 33-36 and 42-47 of SRR1 are loaded with information
- specific to the exception.
+- bits 33-36 and 42-47 of SRR1 are loaded with information specific to the
+ exception.
-- bits 0-32, 37-41, and 48-63 of SRR1 are loaded with corresponding
- bits from the MSR.
+- bits 0-32, 37-41, and 48-63 of SRR1 are loaded with corresponding bits from
+ the MSR.
- the MSR is set based upon the exception type.
-- instruction fetch and execution resumes, using the new MSR value, at a location specific to the execption type.
+- instruction fetch and execution resumes, using the new MSR value, at a
+ location specific to the execption type.
-If the interrupt handler was installed as an RTEMS
-interrupt handler, then upon receipt of the interrupt, the
-processor passes control to the RTEMS interrupt handler which
-performs the following actions:
+If the interrupt handler was installed as an RTEMS interrupt handler, then upon
+receipt of the interrupt, the processor passes control to the RTEMS interrupt
+handler which performs the following actions:
- saves the state of the interrupted task on it's stack,
-- saves all registers which are not normally preserved
- by the calling sequence so the user's interrupt service
- routine can be written in a high-level language.
+- saves all registers which are not normally preserved by the calling sequence
+ so the user's interrupt service routine can be written in a high-level
+ language.
-- if this is the outermost (i.e. non-nested) interrupt,
- then the RTEMS interrupt handler switches from the current stack
- to the interrupt stack,
+- if this is the outermost (i.e. non-nested) interrupt, then the RTEMS
+ interrupt handler switches from the current stack to the interrupt stack,
- enables exceptions,
- invokes the vectors to a user interrupt service routine (ISR).
-Asynchronous interrupts are ignored while exceptions are
-disabled. Synchronous interrupts which occur while are
-disabled result in the CPU being forced into an error mode.
+Asynchronous interrupts are ignored while exceptions are disabled. Synchronous
+interrupts which occur while are disabled result in the CPU being forced into
+an error mode.
-A nested interrupt is processed similarly with the
-exception that the current stack need not be switched to the
-interrupt stack.
+A nested interrupt is processed similarly with the exception that the current
+stack need not be switched to the interrupt stack.
Interrupt Levels
----------------
-The PowerPC architecture supports only a single external
-asynchronous interrupt source. This interrupt source
-may be enabled and disabled via the External Interrupt Enable (EE)
-bit in the Machine State Register (MSR). Thus only two level (enabled
-and disabled) of external device interrupt priorities are
+The PowerPC architecture supports only a single external asynchronous interrupt
+source. This interrupt source may be enabled and disabled via the External
+Interrupt Enable (EE) bit in the Machine State Register (MSR). Thus only two
+level (enabled and disabled) of external device interrupt priorities are
directly supported by the PowerPC architecture.
-Some PowerPC implementations include a Critical Interrupt capability
-which is often used to receive interrupts from high priority external
-devices.
+Some PowerPC implementations include a Critical Interrupt capability which is
+often used to receive interrupts from high priority external devices.
-The RTEMS interrupt level mapping scheme for the PowerPC is not
-a numeric level as on most RTEMS ports. It is a bit mapping in
-which the least three significiant bits of the interrupt level
-are mapped directly to the enabling of specific interrupt
-sources as follows:
+The RTEMS interrupt level mapping scheme for the PowerPC is not a numeric level
+as on most RTEMS ports. It is a bit mapping in which the least three
+significiant bits of the interrupt level are mapped directly to the enabling of
+specific interrupt sources as follows:
*Critical Interrupt*
- Setting bit 0 (the least significant bit) of the interrupt level
- enables the Critical Interrupt source, if it is available on this
- CPU model.
+ Setting bit 0 (the least significant bit) of the interrupt level enables
+ the Critical Interrupt source, if it is available on this CPU model.
*Machine Check*
Setting bit 1 of the interrupt level enables Machine Check execptions.
@@ -528,8 +499,8 @@ All other bits in the RTEMS task interrupt level are ignored.
Default Fatal Error Processing
==============================
-The default fatal error handler for this architecture performs the
-following actions:
+The default fatal error handler for this architecture performs the following
+actions:
- places the error code in r3, and
@@ -558,52 +529,41 @@ Board Support Packages
System Reset
------------
-An RTEMS based application is initiated or
-re-initiated when the PowerPC processor is reset. The PowerPC
-architecture defines a Reset Exception, but leaves the
-details of the CPU state as implementation specific. Please
-refer to the User's Manual for the CPU model in question.
+An RTEMS based application is initiated or re-initiated when the PowerPC
+processor is reset. The PowerPC architecture defines a Reset Exception, but
+leaves the details of the CPU state as implementation specific. Please refer
+to the User's Manual for the CPU model in question.
-In general, at power-up the PowerPC begin execution at address
-0xFFF00100 in supervisor mode with all exceptions disabled. For
-soft resets, the CPU will vector to either 0xFFF00100 or 0x00000100
-depending upon the setting of the Exception Prefix bit in the MSR.
-If during a soft reset, a Machine Check Exception occurs, then the
-CPU may execute a hard reset.
+In general, at power-up the PowerPC begin execution at address 0xFFF00100 in
+supervisor mode with all exceptions disabled. For soft resets, the CPU will
+vector to either 0xFFF00100 or 0x00000100 depending upon the setting of the
+Exception Prefix bit in the MSR. If during a soft reset, a Machine Check
+Exception occurs, then the CPU may execute a hard reset.
Processor Initialization
------------------------
-If this PowerPC implementation supports on-chip caching
-and this is to be utilized, then it should be enabled during the
-reset application initialization code. On-chip caching has been
-observed to prevent some emulators from working properly, so it
-may be necessary to run with caching disabled to use these emulators.
-
-In addition to the requirements described in the*Board Support Packages* chapter of the RTEMS C
-Applications User's Manual for the reset code
-which is executed before the call to ``rtems_initialize_executive``,
-the PowrePC version has the following specific requirements:
-
-- Must leave the PR bit of the Machine State Register (MSR) set
- to 0 so the PowerPC remains in the supervisor state.
+If this PowerPC implementation supports on-chip caching and this is to be
+utilized, then it should be enabled during the reset application initialization
+code. On-chip caching has been observed to prevent some emulators from working
+properly, so it may be necessary to run with caching disabled to use these
+emulators.
-- Must set stack pointer (sp or r1) such that a minimum stack
- size of MINIMUM_STACK_SIZE bytes is provided for the RTEMS initialization
- sequence.
+In addition to the requirements described in the*Board Support Packages*
+chapter of the RTEMS C Applications User's Manual for the reset code which is
+executed before the call to ``rtems_initialize_executive``, the PowrePC version
+has the following specific requirements:
-- Must disable all external interrupts (i.e. clear the EI (EE)
- bit of the machine state register).
+- Must leave the PR bit of the Machine State Register (MSR) set to 0 so the
+ PowerPC remains in the supervisor state.
-- Must enable traps so window overflow and underflow
- conditions can be properly handled.
+- Must set stack pointer (sp or r1) such that a minimum stack size of
+ MINIMUM_STACK_SIZE bytes is provided for the RTEMS initialization sequence.
-- Must initialize the PowerPC's initial Exception Table with default
- handlers.
+- Must disable all external interrupts (i.e. clear the EI (EE) bit of the
+ machine state register).
-.. COMMENT: COPYRIGHT (c) 1988-2002.
-
-.. COMMENT: On-Line Applications Research Corporation (OAR).
-
-.. COMMENT: All rights reserved.
+- Must enable traps so window overflow and underflow conditions can be properly
+ handled.
+- Must initialize the PowerPC's initial Exception Table with default handlers.
diff --git a/cpu_supplement/preface.rst b/cpu_supplement/preface.rst
index d47b9e3..0fa6341 100644
--- a/cpu_supplement/preface.rst
+++ b/cpu_supplement/preface.rst
@@ -1,56 +1,46 @@
.. comment SPDX-License-Identifier: CC-BY-SA-4.0
-=======
-Preface
-=======
-
-
-The Real Time Executive for Multiprocessor Systems
-(RTEMS) is designed to be portable across multiple processor
-architectures. However, the nature of real-time systems makes
-it essential that the application designer understand certain
-processor dependent implementation details. These processor
-dependencies include calling convention, board support package
-issues, interrupt processing, exact RTEMS memory requirements,
-performance data, header files, and the assembly language
-interface to the executive.
-
-Each architecture represents a CPU family and usually there are
-a wide variety of CPU models within it. These models share a
-common Instruction Set Architecture (ISA) which often varies
-based upon some well-defined rules. There are often
-multiple implementations of the ISA and these may be from
-one or multiple vendors.
-
-On top of variations in the ISA, there may also be variations
-which occur when a CPU core implementation is combined with
-a set of peripherals to form a system on chip. For example,
-there are many ARM CPU models from numerous semiconductor
-vendors and a wide variety of peripherals. But at the
-ISA level, they share a common compatibility.
-
-RTEMS depends upon this core similarity across the CPU models
-and leverages that to minimize the source code that is specific
-to any particular CPU core implementation or CPU model.
-
-This manual is separate and distinct from the RTEMS Porting
-Guide. That manual is a guide on porting RTEMS to a new
-architecture. This manual is focused on the more mundane
-CPU architecture specific issues that may impact
-application development. For example, if you need to write
-a subroutine in assembly language, it is critical to understand
-the calling conventions for the target architecture.
-
-The first chapter in this manual describes these issues
-in general terms. In a sense, it is posing the questions
-one should be aware may need to be answered and understood
-when porting an RTEMS application to a new architecture.
-Each subsequent chapter gives the answers to those questions
-for a particular CPU architecture.
-
.. COMMENT: COPYRIGHT (c) 1988-2002.
-
.. COMMENT: On-Line Applications Research Corporation (OAR).
-
.. COMMENT: All rights reserved.
+=======
+Preface
+=======
+
+The Real Time Executive for Multiprocessor Systems (RTEMS) is designed to be
+portable across multiple processor architectures. However, the nature of
+real-time systems makes it essential that the application designer understand
+certain processor dependent implementation details. These processor
+dependencies include calling convention, board support package issues,
+interrupt processing, exact RTEMS memory requirements, performance data, header
+files, and the assembly language interface to the executive.
+
+Each architecture represents a CPU family and usually there are a wide variety
+of CPU models within it. These models share a common Instruction Set
+Architecture (ISA) which often varies based upon some well-defined rules.
+There are often multiple implementations of the ISA and these may be from one
+or multiple vendors.
+
+On top of variations in the ISA, there may also be variations which occur when
+a CPU core implementation is combined with a set of peripherals to form a
+system on chip. For example, there are many ARM CPU models from numerous
+semiconductor vendors and a wide variety of peripherals. But at the ISA level,
+they share a common compatibility.
+
+RTEMS depends upon this core similarity across the CPU models and leverages
+that to minimize the source code that is specific to any particular CPU core
+implementation or CPU model.
+
+This manual is separate and distinct from the RTEMS Porting Guide. That manual
+is a guide on porting RTEMS to a new architecture. This manual is focused on
+the more mundane CPU architecture specific issues that may impact application
+development. For example, if you need to write a subroutine in assembly
+language, it is critical to understand the calling conventions for the target
+architecture.
+
+The first chapter in this manual describes these issues in general terms. In a
+sense, it is posing the questions one should be aware may need to be answered
+and understood when porting an RTEMS application to a new architecture. Each
+subsequent chapter gives the answers to those questions for a particular CPU
+architecture.
diff --git a/cpu_supplement/renesas_m32c.rst b/cpu_supplement/renesas_m32c.rst
index 5b560a3..4884e15 100644
--- a/cpu_supplement/renesas_m32c.rst
+++ b/cpu_supplement/renesas_m32c.rst
@@ -1,5 +1,9 @@
.. comment SPDX-License-Identifier: CC-BY-SA-4.0
+.. COMMENT: COPYRIGHT (c) 1988-2002.
+.. COMMENT: On-Line Applications Research Corporation (OAR).
+.. COMMENT: All rights reserved.
+
Renesas M32C Specific Information
#################################
@@ -12,10 +16,3 @@ Thread-Local Storage
====================
Thread-local storage is not implemented.
-
-.. COMMENT: COPYRIGHT (c) 1988-2002.
-
-.. COMMENT: On-Line Applications Research Corporation (OAR).
-
-.. COMMENT: All rights reserved.
-
diff --git a/cpu_supplement/sparc.rst b/cpu_supplement/sparc.rst
index 3c32135..6b16bb6 100644
--- a/cpu_supplement/sparc.rst
+++ b/cpu_supplement/sparc.rst
@@ -1,33 +1,33 @@
.. comment SPDX-License-Identifier: CC-BY-SA-4.0
+.. COMMENT: COPYRIGHT (c) 1988-2002.
+.. COMMENT: On-Line Applications Research Corporation (OAR).
+.. COMMENT: All rights reserved.
+
SPARC Specific Information
##########################
-The Real Time Executive for Multiprocessor Systems
-(RTEMS) is designed to be portable across multiple processor
-architectures. However, the nature of real-time systems makes
-it essential that the application designer understand certain
-processor dependent implementation details. These processor
-dependencies include calling convention, board support package
-issues, interrupt processing, exact RTEMS memory requirements,
-performance data, header files, and the assembly language
-interface to the executive.
-
-This document discusses the SPARC architecture dependencies in this
-port of RTEMS. This architectural port is for SPARC Version 7 and
+The Real Time Executive for Multiprocessor Systems (RTEMS) is designed to be
+portable across multiple processor architectures. However, the nature of
+real-time systems makes it essential that the application designer understand
+certain processor dependent implementation details. These processor
+dependencies include calling convention, board support package issues,
+interrupt processing, exact RTEMS memory requirements, performance data, header
+files, and the assembly language interface to the executive.
+
+This document discusses the SPARC architecture dependencies in this port of
+RTEMS. This architectural port is for SPARC Version 7 and
8. Implementations for SPARC V9 are in the sparc64 target.
-It is highly recommended that the SPARC RTEMS
-application developer obtain and become familiar with the
-documentation for the processor being used as well as the
-specification for the revision of the SPARC architecture which
-corresponds to that processor.
+It is highly recommended that the SPARC RTEMS application developer obtain and
+become familiar with the documentation for the processor being used as well as
+the specification for the revision of the SPARC architecture which corresponds
+to that processor.
**SPARC Architecture Documents**
-For information on the SPARC architecture, refer to
-the following documents available from SPARC International, Inc.
-(http://www.sparc.com):
+For information on the SPARC architecture, refer to the following documents
+available from SPARC International, Inc. (http://www.sparc.com):
- SPARC Standard Version 7.
@@ -35,35 +35,30 @@ the following documents available from SPARC International, Inc.
**ERC32 Specific Information**
-The European Space Agency's ERC32 is a three chip
-computing core implementing a SPARC V7 processor and associated
-support circuitry for embedded space applications. The integer
-and floating-point units (90C601E & 90C602E) are based on the
-Cypress 7C601 and 7C602, with additional error-detection and
-recovery functions. The memory controller (MEC) implements
-system support functions such as address decoding, memory
-interface, DMA interface, UARTs, timers, interrupt control,
-write-protection, memory reconfiguration and error-detection.
-The core is designed to work at 25MHz, but using space qualified
-memories limits the system frequency to around 15 MHz, resulting
-in a performance of 10 MIPS and 2 MFLOPS.
-
-Information on the ERC32 and a number of development
-support tools, such as the SPARC Instruction Simulator (SIS),
-are freely available on the Internet. The following documents
-and SIS are available via anonymous ftp or pointing your web
-browser at ftp://ftp.estec.esa.nl/pub/ws/wsd/erc32.
+The European Space Agency's ERC32 is a three chip computing core implementing a
+SPARC V7 processor and associated support circuitry for embedded space
+applications. The integer and floating-point units (90C601E & 90C602E) are
+based on the Cypress 7C601 and 7C602, with additional error-detection and
+recovery functions. The memory controller (MEC) implements system support
+functions such as address decoding, memory interface, DMA interface, UARTs,
+timers, interrupt control, write-protection, memory reconfiguration and
+error-detection. The core is designed to work at 25MHz, but using space
+qualified memories limits the system frequency to around 15 MHz, resulting in a
+performance of 10 MIPS and 2 MFLOPS.
+
+Information on the ERC32 and a number of development support tools, such as the
+SPARC Instruction Simulator (SIS), are freely available on the Internet. The
+following documents and SIS are available via anonymous ftp or pointing your
+web browser at ftp://ftp.estec.esa.nl/pub/ws/wsd/erc32.
- ERC32 System Design Document
- MEC Device Specification
-Additionally, the SPARC RISC User's Guide from Matra
-MHS documents the functionality of the integer and floating
-point units including the instruction set information. To
-obtain this document as well as ERC32 components and VHDL models
-contact:
-.. code:: c
+Additionally, the SPARC RISC User's Guide from Matra MHS documents the
+functionality of the integer and floating point units including the instruction
+set information. To obtain this document as well as ERC32 components and VHDL
+models contact:
Matra MHS SA
3 Avenue du Centre, BP 309,
@@ -74,102 +69,85 @@ contact:
Amar Guennon (amar.guennon@matramhs.fr) is familiar with the ERC32.
-.. COMMENT: COPYRIGHT (c) 1988-2002.
-
-.. COMMENT: On-Line Applications Research Corporation (OAR).
-
-.. COMMENT: All rights reserved.
-
CPU Model Dependent Features
============================
-Microprocessors are generally classified into
-families with a variety of CPU models or implementations within
-that family. Within a processor family, there is a high level
-of binary compatibility. This family may be based on either an
-architectural specification or on maintaining compatibility with
-a popular processor. Recent microprocessor families such as the
-SPARC or PowerPC are based on an architectural specification
-which is independent or any particular CPU model or
-implementation. Older families such as the M68xxx and the iX86
-evolved as the manufacturer strived to produce higher
-performance processor models which maintained binary
-compatibility with older models.
-
-RTEMS takes advantage of the similarity of the
-various models within a CPU family. Although the models do vary
-in significant ways, the high level of compatibility makes it
-possible to share the bulk of the CPU dependent executive code
-across the entire family.
+Microprocessors are generally classified into families with a variety of CPU
+models or implementations within that family. Within a processor family, there
+is a high level of binary compatibility. This family may be based on either an
+architectural specification or on maintaining compatibility with a popular
+processor. Recent microprocessor families such as the SPARC or PowerPC are
+based on an architectural specification which is independent or any particular
+CPU model or implementation. Older families such as the M68xxx and the iX86
+evolved as the manufacturer strived to produce higher performance processor
+models which maintained binary compatibility with older models.
+
+RTEMS takes advantage of the similarity of the various models within a CPU
+family. Although the models do vary in significant ways, the high level of
+compatibility makes it possible to share the bulk of the CPU dependent
+executive code across the entire family.
CPU Model Feature Flags
-----------------------
-Each processor family supported by RTEMS has a
-list of features which vary between CPU models
-within a family. For example, the most common model dependent
-feature regardless of CPU family is the presence or absence of a
-floating point unit or coprocessor. When defining the list of
-features present on a particular CPU model, one simply notes
-that floating point hardware is or is not present and defines a
-single constant appropriately. Conditional compilation is
-utilized to include the appropriate source code for this CPU
-model's feature set. It is important to note that this means
-that RTEMS is thus compiled using the appropriate feature set
-and compilation flags optimal for this CPU model used. The
-alternative would be to generate a binary which would execute on
-all family members using only the features which were always
+Each processor family supported by RTEMS has a list of features which vary
+between CPU models within a family. For example, the most common model
+dependent feature regardless of CPU family is the presence or absence of a
+floating point unit or coprocessor. When defining the list of features present
+on a particular CPU model, one simply notes that floating point hardware is or
+is not present and defines a single constant appropriately. Conditional
+compilation is utilized to include the appropriate source code for this CPU
+model's feature set. It is important to note that this means that RTEMS is
+thus compiled using the appropriate feature set and compilation flags optimal
+for this CPU model used. The alternative would be to generate a binary which
+would execute on all family members using only the features which were always
present.
-This section presents the set of features which vary
-across SPARC implementations and are of importance to RTEMS.
-The set of CPU model feature macros are defined in the file
-cpukit/score/cpu/sparc/sparc.h based upon the particular CPU
-model defined on the compilation command line.
+This section presents the set of features which vary across SPARC
+implementations and are of importance to RTEMS. The set of CPU model feature
+macros are defined in the file cpukit/score/cpu/sparc/sparc.h based upon the
+particular CPU model defined on the compilation command line.
CPU Model Name
~~~~~~~~~~~~~~
-The macro CPU_MODEL_NAME is a string which designates
-the name of this CPU model. For example, for the European Space
-Agency's ERC32 SPARC model, this macro is set to the string
-"erc32".
+The macro CPU_MODEL_NAME is a string which designates the name of this CPU
+model. For example, for the European Space Agency's ERC32 SPARC model, this
+macro is set to the string "erc32".
Floating Point Unit
~~~~~~~~~~~~~~~~~~~
-The macro SPARC_HAS_FPU is set to 1 to indicate that
-this CPU model has a hardware floating point unit and 0
-otherwise.
+The macro SPARC_HAS_FPU is set to 1 to indicate that this CPU model has a
+hardware floating point unit and 0 otherwise.
Bitscan Instruction
~~~~~~~~~~~~~~~~~~~
-The macro SPARC_HAS_BITSCAN is set to 1 to indicate
-that this CPU model has the bitscan instruction. For example,
-this instruction is supported by the Fujitsu SPARClite family.
+The macro SPARC_HAS_BITSCAN is set to 1 to indicate that this CPU model has the
+bitscan instruction. For example, this instruction is supported by the Fujitsu
+SPARClite family.
Number of Register Windows
~~~~~~~~~~~~~~~~~~~~~~~~~~
-The macro SPARC_NUMBER_OF_REGISTER_WINDOWS is set to
-indicate the number of register window sets implemented by this
-CPU model. The SPARC architecture allows a for a maximum of
-thirty-two register window sets although most implementations
-only include eight.
+The macro SPARC_NUMBER_OF_REGISTER_WINDOWS is set to indicate the number of
+register window sets implemented by this CPU model. The SPARC architecture
+allows a for a maximum of thirty-two register window sets although most
+implementations only include eight.
Low Power Mode
~~~~~~~~~~~~~~
-The macro SPARC_HAS_LOW_POWER_MODE is set to one to
-indicate that this CPU model has a low power mode. If low power
-is enabled, then there must be CPU model specific implementation
-of the IDLE task in cpukit/score/cpu/sparc/cpu.c. The low
-power mode IDLE task should be of the form:
-.. code:: c
+The macro SPARC_HAS_LOW_POWER_MODE is set to one to indicate that this CPU
+model has a low power mode. If low power is enabled, then there must be CPU
+model specific implementation of the IDLE task in cpukit/score/cpu/sparc/cpu.c.
+The low power mode IDLE task should be of the form:
+
+.. code-block:: c
while ( TRUE ) {
- enter low power mode
+ enter low power mode
}
The code required to enter low power mode is CPU model specific.
@@ -202,26 +180,20 @@ only, we must mirror it in software and insure that writes to one timer do not
alter the current settings and status of the other timer. Routines are
provided in erc32.h which promote the view that the two timers are completely
independent. By exclusively using these routines to access the Timer Control
-Register, the application can view the system as having a General Purpose
-Timer Control Register and a Real Time Clock Timer Control Register
-rather than the single shared value.
+Register, the application can view the system as having a General Purpose Timer
+Control Register and a Real Time Clock Timer Control Register rather than the
+single shared value.
The RTEMS Idle thread take advantage of the low power mode provided by the
ERC32. Low power mode is entered during idle loops and is enabled at
initialization time.
-.. COMMENT: COPYRIGHT (c) 1988-2002.
-
-.. COMMENT: On-Line Applications Research Corporation (OAR).
-
-.. COMMENT: All rights reserved.
-
Calling Conventions
===================
Each high-level language compiler generates subroutine entry and exit code
based upon a set of rules known as the application binary interface (ABI)
-calling convention. These rules address the following issues:
+calling convention. These rules address the following issues:
- register preservation and usage
@@ -240,15 +212,13 @@ INTERFACE, SPARC Processor Supplement, Third Edition.
Programming Model
-----------------
-This section discusses the programming model for the
-SPARC architecture.
+This section discusses the programming model for the SPARC architecture.
Non-Floating Point Registers
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-The SPARC architecture defines thirty-two
-non-floating point registers directly visible to the programmer.
-These are divided into four sets:
+The SPARC architecture defines thirty-two non-floating point registers directly
+visible to the programmer. These are divided into four sets:
- input registers
@@ -258,47 +228,42 @@ These are divided into four sets:
- global registers
-Each register is referred to by either two or three
-names in the SPARC reference manuals. First, the registers are
-referred to as r0 through r31 or with the alternate notation
-r[0] through r[31]. Second, each register is a member of one of
-the four sets listed above. Finally, some registers have an
-architecturally defined role in the programming model which
-provides an alternate name. The following table describes the
-mapping between the 32 registers and the register sets:
-
-.. code:: c
-
- +-----------------+----------------+------------------+
- | Register Number | Register Names | Description |
- +-----------------+----------------+------------------+
- | 0 - 7 | g0 - g7 | Global Registers |
- +-----------------+----------------+------------------+
- | 8 - 15 | o0 - o7 | Output Registers |
- +-----------------+----------------+------------------+
- | 16 - 23 | l0 - l7 | Local Registers |
- +-----------------+----------------+------------------+
- | 24 - 31 | i0 - i7 | Input Registers |
- +-----------------+----------------+------------------+
-
-As mentioned above, some of the registers serve
-defined roles in the programming model. The following table
-describes the role of each of these registers:
-
-.. code:: c
-
- +---------------+----------------+----------------------+
- | Register Name | Alternate Name | Description |
- +---------------+----------------+----------------------+
- | g0 | na | reads return 0 |
- | | | writes are ignored |
- +---------------+----------------+----------------------+
- | o6 | sp | stack pointer |
- +---------------+----------------+----------------------+
- | i6 | fp | frame pointer |
- +---------------+----------------+----------------------+
- | i7 | na | return address |
- +---------------+----------------+----------------------+
+Each register is referred to by either two or three names in the SPARC
+reference manuals. First, the registers are referred to as r0 through r31 or
+with the alternate notation r[0] through r[31]. Second, each register is a
+member of one of the four sets listed above. Finally, some registers have an
+architecturally defined role in the programming model which provides an
+alternate name. The following table describes the mapping between the 32
+registers and the register sets:
+
++-----------------+----------------+------------------+
+| Register Number | Register Names | Description |
++-----------------+----------------+------------------+
+| 0 - 7 | g0 - g7 | Global Registers |
++-----------------+----------------+------------------+
+| 8 - 15 | o0 - o7 | Output Registers |
++-----------------+----------------+------------------+
+| 16 - 23 | l0 - l7 | Local Registers |
++-----------------+----------------+------------------+
+| 24 - 31 | i0 - i7 | Input Registers |
++-----------------+----------------+------------------+
+
+As mentioned above, some of the registers serve defined roles in the
+programming model. The following table describes the role of each of these
+registers:
+
++---------------+----------------+----------------------+
+| Register Name | Alternate Name | Description |
++---------------+----------------+----------------------+
+| g0 | na | reads return 0 |
+| | | writes are ignored |
++---------------+----------------+----------------------+
+| o6 | sp | stack pointer |
++---------------+----------------+----------------------+
+| i6 | fp | frame pointer |
++---------------+----------------+----------------------+
+| i7 | na | return address |
++---------------+----------------+----------------------+
The registers g2 through g4 are reserved for applications. GCC uses them as
volatile registers by default. So they are treated like volatile registers in
@@ -315,166 +280,140 @@ pointer used for thread-local storage (TLS) as mandated by the SPARC ABI.
Floating Point Registers
~~~~~~~~~~~~~~~~~~~~~~~~
-The SPARC V7 architecture includes thirty-two,
-thirty-two bit registers. These registers may be viewed as
-follows:
+The SPARC V7 architecture includes thirty-two, thirty-two bit registers. These
+registers may be viewed as follows:
-- 32 single precision floating point or integer registers
- (f0, f1, ... f31)
+- 32 single precision floating point or integer registers (f0, f1, ... f31)
-- 16 double precision floating point registers (f0, f2,
- f4, ... f30)
+- 16 double precision floating point registers (f0, f2, f4, ... f30)
-- 8 extended precision floating point registers (f0, f4,
- f8, ... f28)
+- 8 extended precision floating point registers (f0, f4, f8, ... f28)
-The floating point status register (FSR) specifies
-the behavior of the floating point unit for rounding, contains
-its condition codes, version specification, and trap information.
+The floating point status register (FSR) specifies the behavior of the floating
+point unit for rounding, contains its condition codes, version specification,
+and trap information.
According to the ABI all floating point registers and the floating point status
-register (FSR) are volatile. Thus the floating point context of a thread is the
-empty set. The rounding direction is a system global state and must not be
+register (FSR) are volatile. Thus the floating point context of a thread is
+the empty set. The rounding direction is a system global state and must not be
modified by threads.
-A queue of the floating point instructions which have
-started execution but not yet completed is maintained. This
-queue is needed to support the multiple cycle nature of floating
-point operations and to aid floating point exception trap
-handlers. Once a floating point exception has been encountered,
-the queue is frozen until it is emptied by the trap handler.
-The floating point queue is loaded by launching instructions.
-It is emptied normally when the floating point completes all
-outstanding instructions and by floating point exception
-handlers with the store double floating point queue (stdfq)
-instruction.
+A queue of the floating point instructions which have started execution but not
+yet completed is maintained. This queue is needed to support the multiple
+cycle nature of floating point operations and to aid floating point exception
+trap handlers. Once a floating point exception has been encountered, the queue
+is frozen until it is emptied by the trap handler. The floating point queue is
+loaded by launching instructions. It is emptied normally when the floating
+point completes all outstanding instructions and by floating point exception
+handlers with the store double floating point queue (stdfq) instruction.
Special Registers
~~~~~~~~~~~~~~~~~
-The SPARC architecture includes two special registers
-which are critical to the programming model: the Processor State
-Register (psr) and the Window Invalid Mask (wim). The psr
-contains the condition codes, processor interrupt level, trap
-enable bit, supervisor mode and previous supervisor mode bits,
-version information, floating point unit and coprocessor enable
-bits, and the current window pointer (cwp). The cwp field of
-the psr and wim register are used to manage the register windows
-in the SPARC architecture. The register windows are discussed
-in more detail below.
+The SPARC architecture includes two special registers which are critical to the
+programming model: the Processor State Register (psr) and the Window Invalid
+Mask (wim). The psr contains the condition codes, processor interrupt level,
+trap enable bit, supervisor mode and previous supervisor mode bits, version
+information, floating point unit and coprocessor enable bits, and the current
+window pointer (cwp). The cwp field of the psr and wim register are used to
+manage the register windows in the SPARC architecture. The register windows
+are discussed in more detail below.
Register Windows
----------------
-The SPARC architecture includes the concept of
-register windows. An overly simplistic way to think of these
-windows is to imagine them as being an infinite supply of
-"fresh" register sets available for each subroutine to use. In
-reality, they are much more complicated.
-
-The save instruction is used to obtain a new register
-window. This instruction decrements the current window pointer,
-thus providing a new set of registers for use. This register
-set includes eight fresh local registers for use exclusively by
-this subroutine. When done with a register set, the restore
-instruction increments the current window pointer and the
-previous register set is once again available.
-
-The two primary issues complicating the use of
-register windows are that (1) the set of register windows is
-finite, and (2) some registers are shared between adjacent
-registers windows.
-
-Because the set of register windows is finite, it is
-possible to execute enough save instructions without
-corresponding restore's to consume all of the register windows.
-This is easily accomplished in a high level language because
-each subroutine typically performs a save instruction upon
-entry. Thus having a subroutine call depth greater than the
-number of register windows will result in a window overflow
-condition. The window overflow condition generates a trap which
-must be handled in software. The window overflow trap handler
-is responsible for saving the contents of the oldest register
-window on the program stack.
-
-Similarly, the subroutines will eventually complete
-and begin to perform restore's. If the restore results in the
-need for a register window which has previously been written to
-memory as part of an overflow, then a window underflow condition
-results. Just like the window overflow, the window underflow
-condition must be handled in software by a trap handler. The
-window underflow trap handler is responsible for reloading the
-contents of the register window requested by the restore
-instruction from the program stack.
-
-The Window Invalid Mask (wim) and the Current Window
-Pointer (cwp) field in the psr are used in conjunction to manage
-the finite set of register windows and detect the window
-overflow and underflow conditions. The cwp contains the index
-of the register window currently in use. The save instruction
-decrements the cwp modulo the number of register windows.
-Similarly, the restore instruction increments the cwp modulo the
-number of register windows. Each bit in the wim represents
-represents whether a register window contains valid information.
-The value of 0 indicates the register window is valid and 1
-indicates it is invalid. When a save instruction causes the cwp
-to point to a register window which is marked as invalid, a
-window overflow condition results. Conversely, the restore
-instruction may result in a window underflow condition.
-
-Other than the assumption that a register window is
-always available for trap (i.e. interrupt) handlers, the SPARC
-architecture places no limits on the number of register windows
-simultaneously marked as invalid (i.e. number of bits set in the
-wim). However, RTEMS assumes that only one register window is
-marked invalid at a time (i.e. only one bit set in the wim).
-This makes the maximum possible number of register windows
-available to the user while still meeting the requirement that
-window overflow and underflow conditions can be detected.
-
-The window overflow and window underflow trap
-handlers are a critical part of the run-time environment for a
-SPARC application. The SPARC architectural specification allows
-for the number of register windows to be any power of two less
-than or equal to 32. The most common choice for SPARC
-implementations appears to be 8 register windows. This results
-in the cwp ranging in value from 0 to 7 on most implementations.
-
-The second complicating factor is the sharing of
-registers between adjacent register windows. While each
-register window has its own set of local registers, the input
-and output registers are shared between adjacent windows. The
-output registers for register window N are the same as the input
-registers for register window ((N - 1) modulo RW) where RW is
-the number of register windows. An alternative way to think of
-this is to remember how parameters are passed to a subroutine on
-the SPARC. The caller loads values into what are its output
-registers. Then after the callee executes a save instruction,
-those parameters are available in its input registers. This is
-a very efficient way to pass parameters as no data is actually
-moved by the save or restore instructions.
+The SPARC architecture includes the concept of register windows. An overly
+simplistic way to think of these windows is to imagine them as being an
+infinite supply of "fresh" register sets available for each subroutine to use.
+In reality, they are much more complicated.
+
+The save instruction is used to obtain a new register window. This instruction
+decrements the current window pointer, thus providing a new set of registers
+for use. This register set includes eight fresh local registers for use
+exclusively by this subroutine. When done with a register set, the restore
+instruction increments the current window pointer and the previous register set
+is once again available.
+
+The two primary issues complicating the use of register windows are that (1)
+the set of register windows is finite, and (2) some registers are shared
+between adjacent registers windows.
+
+Because the set of register windows is finite, it is possible to execute enough
+save instructions without corresponding restore's to consume all of the
+register windows. This is easily accomplished in a high level language because
+each subroutine typically performs a save instruction upon entry. Thus having
+a subroutine call depth greater than the number of register windows will result
+in a window overflow condition. The window overflow condition generates a trap
+which must be handled in software. The window overflow trap handler is
+responsible for saving the contents of the oldest register window on the
+program stack.
+
+Similarly, the subroutines will eventually complete and begin to perform
+restore's. If the restore results in the need for a register window which has
+previously been written to memory as part of an overflow, then a window
+underflow condition results. Just like the window overflow, the window
+underflow condition must be handled in software by a trap handler. The window
+underflow trap handler is responsible for reloading the contents of the
+register window requested by the restore instruction from the program stack.
+
+The Window Invalid Mask (wim) and the Current Window Pointer (cwp) field in the
+psr are used in conjunction to manage the finite set of register windows and
+detect the window overflow and underflow conditions. The cwp contains the
+index of the register window currently in use. The save instruction decrements
+the cwp modulo the number of register windows. Similarly, the restore
+instruction increments the cwp modulo the number of register windows. Each bit
+in the wim represents represents whether a register window contains valid
+information. The value of 0 indicates the register window is valid and 1
+indicates it is invalid. When a save instruction causes the cwp to point to a
+register window which is marked as invalid, a window overflow condition
+results. Conversely, the restore instruction may result in a window underflow
+condition.
+
+Other than the assumption that a register window is always available for trap
+(i.e. interrupt) handlers, the SPARC architecture places no limits on the
+number of register windows simultaneously marked as invalid (i.e. number of
+bits set in the wim). However, RTEMS assumes that only one register window is
+marked invalid at a time (i.e. only one bit set in the wim). This makes the
+maximum possible number of register windows available to the user while still
+meeting the requirement that window overflow and underflow conditions can be
+detected.
+
+The window overflow and window underflow trap handlers are a critical part of
+the run-time environment for a SPARC application. The SPARC architectural
+specification allows for the number of register windows to be any power of two
+less than or equal to 32. The most common choice for SPARC implementations
+appears to be 8 register windows. This results in the cwp ranging in value
+from 0 to 7 on most implementations.
+
+The second complicating factor is the sharing of registers between adjacent
+register windows. While each register window has its own set of local
+registers, the input and output registers are shared between adjacent windows.
+The output registers for register window N are the same as the input registers
+for register window ((N - 1) modulo RW) where RW is the number of register
+windows. An alternative way to think of this is to remember how parameters are
+passed to a subroutine on the SPARC. The caller loads values into what are its
+output registers. Then after the callee executes a save instruction, those
+parameters are available in its input registers. This is a very efficient way
+to pass parameters as no data is actually moved by the save or restore
+instructions.
Call and Return Mechanism
-------------------------
-The SPARC architecture supports a simple yet
-effective call and return mechanism. A subroutine is invoked
-via the call (call) instruction. This instruction places the
-return address in the caller's output register 7 (o7). After
-the callee executes a save instruction, this value is available
-in input register 7 (i7) until the corresponding restore
-instruction is executed.
-
-The callee returns to the caller via a jmp to the
-return address. There is a delay slot following this
-instruction which is commonly used to execute a restore
-instruction - if a register window was allocated by this
-subroutine.
-
-It is important to note that the SPARC subroutine
-call and return mechanism does not automatically save and
-restore any registers. This is accomplished via the save and
-restore instructions which manage the set of registers windows.
+The SPARC architecture supports a simple yet effective call and return
+mechanism. A subroutine is invoked via the call (call) instruction. This
+instruction places the return address in the caller's output register 7 (o7).
+After the callee executes a save instruction, this value is available in input
+register 7 (i7) until the corresponding restore instruction is executed.
+
+The callee returns to the caller via a jmp to the return address. There is a
+delay slot following this instruction which is commonly used to execute a
+restore instruction - if a register window was allocated by this subroutine.
+
+It is important to note that the SPARC subroutine call and return mechanism
+does not automatically save and restore any registers. This is accomplished
+via the save and restore instructions which manage the set of registers
+windows.
In case a floating-point unit is supported, then floating-point return values
appear in the floating-point registers. Single-precision values occupy %f0;
@@ -485,32 +424,30 @@ incompatible.
Calling Mechanism
-----------------
-All RTEMS directives are invoked using the regular
-SPARC calling convention via the call instruction.
+All RTEMS directives are invoked using the regular SPARC calling convention via
+the call instruction.
Register Usage
--------------
-As discussed above, the call instruction does not
-automatically save any registers. The save and restore
-instructions are used to allocate and deallocate register
-windows. When a register window is allocated, the new set of
-local registers are available for the exclusive use of the
-subroutine which allocated this register set.
+As discussed above, the call instruction does not automatically save any
+registers. The save and restore instructions are used to allocate and
+deallocate register windows. When a register window is allocated, the new set
+of local registers are available for the exclusive use of the subroutine which
+allocated this register set.
Parameter Passing
-----------------
-RTEMS assumes that arguments are placed in the
-caller's output registers with the first argument in output
-register 0 (o0), the second argument in output register 1 (o1),
-and so forth. Until the callee executes a save instruction, the
-parameters are still visible in the output registers. After the
-callee executes a save instruction, the parameters are visible
-in the corresponding input registers. The following pseudo-code
-illustrates the typical sequence used to call a RTEMS directive
-with three (3) arguments:
-.. code:: c
+RTEMS assumes that arguments are placed in the caller's output registers with
+the first argument in output register 0 (o0), the second argument in output
+register 1 (o1), and so forth. Until the callee executes a save instruction,
+the parameters are still visible in the output registers. After the callee
+executes a save instruction, the parameters are visible in the corresponding
+input registers. The following pseudo-code illustrates the typical sequence
+used to call a RTEMS directive with three (3) arguments:
+
+.. code-block:: c
load third argument into o2
load second argument into o1
@@ -520,43 +457,31 @@ with three (3) arguments:
User-Provided Routines
----------------------
-All user-provided routines invoked by RTEMS, such as
-user extensions, device drivers, and MPCI routines, must also
-adhere to these calling conventions.
-
-.. COMMENT: COPYRIGHT (c) 1988-2002.
-
-.. COMMENT: On-Line Applications Research Corporation (OAR).
-
-.. COMMENT: All rights reserved.
+All user-provided routines invoked by RTEMS, such as user extensions, device
+drivers, and MPCI routines, must also adhere to these calling conventions.
Memory Model
============
-A processor may support any combination of memory
-models ranging from pure physical addressing to complex demand
-paged virtual memory systems. RTEMS supports a flat memory
-model which ranges contiguously over the processor's allowable
-address space. RTEMS does not support segmentation or virtual
-memory of any kind. The appropriate memory model for RTEMS
-provided by the targeted processor and related characteristics
-of that model are described in this chapter.
+A processor may support any combination of memory models ranging from pure
+physical addressing to complex demand paged virtual memory systems. RTEMS
+supports a flat memory model which ranges contiguously over the processor's
+allowable address space. RTEMS does not support segmentation or virtual memory
+of any kind. The appropriate memory model for RTEMS provided by the targeted
+processor and related characteristics of that model are described in this
+chapter.
Flat Memory Model
-----------------
-The SPARC architecture supports a flat 32-bit address
-space with addresses ranging from 0x00000000 to 0xFFFFFFFF (4
-gigabytes). Each address is represented by a 32-bit value and
-is byte addressable. The address may be used to reference a
-single byte, half-word (2-bytes), word (4 bytes), or doubleword
-(8 bytes). Memory accesses within this address space are
-performed in big endian fashion by the SPARC. Memory accesses
-which are not properly aligned generate a "memory address not
-aligned" trap (type number 7). The following table lists the
-alignment requirements for a variety of data accesses:
-
-.. code:: c
+The SPARC architecture supports a flat 32-bit address space with addresses
+ranging from 0x00000000 to 0xFFFFFFFF (4 gigabytes). Each address is
+represented by a 32-bit value and is byte addressable. The address may be used
+to reference a single byte, half-word (2-bytes), word (4 bytes), or doubleword
+(8 bytes). Memory accesses within this address space are performed in big
+endian fashion by the SPARC. Memory accesses which are not properly aligned
+generate a "memory address not aligned" trap (type number 7). The following
+table lists the alignment requirements for a variety of data accesses:
+--------------+-----------------------+
| Data Type | Alignment Requirement |
@@ -567,279 +492,231 @@ alignment requirements for a variety of data accesses:
| doubleword | 8 |
+--------------+-----------------------+
-Doubleword load and store operations must use a pair
-of registers as their source or destination. This pair of
-registers must be an adjacent pair of registers with the first
-of the pair being even numbered. For example, a valid
-destination for a doubleword load might be input registers 0 and
-1 (i0 and i1). The pair i1 and i2 would be invalid. \[NOTE:
-Some assemblers for the SPARC do not generate an error if an odd
-numbered register is specified as the beginning register of the
-pair. In this case, the assembler assumes that what the
-programmer meant was to use the even-odd pair which ends at the
-specified register. This may or may not have been a correct
-assumption.]
-
-RTEMS does not support any SPARC Memory Management
-Units, therefore, virtual memory or segmentation systems
-involving the SPARC are not supported.
-
-.. COMMENT: COPYRIGHT (c) 1988-2002.
+Doubleword load and store operations must use a pair of registers as their
+source or destination. This pair of registers must be an adjacent pair of
+registers with the first of the pair being even numbered. For example, a valid
+destination for a doubleword load might be input registers 0 and 1 (i0 and i1).
+The pair i1 and i2 would be invalid. \[NOTE: Some assemblers for the SPARC do
+not generate an error if an odd numbered register is specified as the beginning
+register of the pair. In this case, the assembler assumes that what the
+programmer meant was to use the even-odd pair which ends at the specified
+register. This may or may not have been a correct assumption.]
-.. COMMENT: On-Line Applications Research Corporation (OAR).
-
-.. COMMENT: All rights reserved.
+RTEMS does not support any SPARC Memory Management Units, therefore, virtual
+memory or segmentation systems involving the SPARC are not supported.
Interrupt Processing
====================
-Different types of processors respond to the
-occurrence of an interrupt in its own unique fashion. In
-addition, each processor type provides a control mechanism to
-allow for the proper handling of an interrupt. The processor
-dependent response to the interrupt modifies the current
-execution state and results in a change in the execution stream.
-Most processors require that an interrupt handler utilize some
-special control mechanisms to return to the normal processing
-stream. Although RTEMS hides many of the processor dependent
-details of interrupt processing, it is important to understand
-how the RTEMS interrupt manager is mapped onto the processor's
-unique architecture. Discussed in this chapter are the SPARC's
-interrupt response and control mechanisms as they pertain to
-RTEMS.
-
-RTEMS and associated documentation uses the terms
-interrupt and vector. In the SPARC architecture, these terms
-correspond to traps and trap type, respectively. The terms will
-be used interchangeably in this manual.
+Different types of processors respond to the occurrence of an interrupt in its
+own unique fashion. In addition, each processor type provides a control
+mechanism to allow for the proper handling of an interrupt. The processor
+dependent response to the interrupt modifies the current execution state and
+results in a change in the execution stream. Most processors require that an
+interrupt handler utilize some special control mechanisms to return to the
+normal processing stream. Although RTEMS hides many of the processor dependent
+details of interrupt processing, it is important to understand how the RTEMS
+interrupt manager is mapped onto the processor's unique architecture. Discussed
+in this chapter are the SPARC's interrupt response and control mechanisms as
+they pertain to RTEMS.
+
+RTEMS and associated documentation uses the terms interrupt and vector. In the
+SPARC architecture, these terms correspond to traps and trap type,
+respectively. The terms will be used interchangeably in this manual.
Synchronous Versus Asynchronous Traps
-------------------------------------
-The SPARC architecture includes two classes of traps:
-synchronous and asynchronous. Asynchronous traps occur when an
-external event interrupts the processor. These traps are not
-associated with any instruction executed by the processor and
-logically occur between instructions. The instruction currently
-in the execute stage of the processor is allowed to complete
-although subsequent instructions are annulled. The return
-address reported by the processor for asynchronous traps is the
-pair of instructions following the current instruction.
-
-Synchronous traps are caused by the actions of an
-instruction. The trap stimulus in this case either occurs
-internally to the processor or is from an external signal that
-was provoked by the instruction. These traps are taken
-immediately and the instruction that caused the trap is aborted
-before any state changes occur in the processor itself. The
-return address reported by the processor for synchronous traps
-is the instruction which caused the trap and the following
-instruction.
+The SPARC architecture includes two classes of traps: synchronous and
+asynchronous. Asynchronous traps occur when an external event interrupts the
+processor. These traps are not associated with any instruction executed by the
+processor and logically occur between instructions. The instruction currently
+in the execute stage of the processor is allowed to complete although
+subsequent instructions are annulled. The return address reported by the
+processor for asynchronous traps is the pair of instructions following the
+current instruction.
+
+Synchronous traps are caused by the actions of an instruction. The trap
+stimulus in this case either occurs internally to the processor or is from an
+external signal that was provoked by the instruction. These traps are taken
+immediately and the instruction that caused the trap is aborted before any
+state changes occur in the processor itself. The return address reported by
+the processor for synchronous traps is the instruction which caused the trap
+and the following instruction.
Vectoring of Interrupt Handler
------------------------------
-Upon receipt of an interrupt the SPARC automatically
-performs the following actions:
+Upon receipt of an interrupt the SPARC automatically performs the following
+actions:
- disables traps (sets the ET bit of the psr to 0),
-- the S bit of the psr is copied into the Previous
- Supervisor Mode (PS) bit of the psr,
+- the S bit of the psr is copied into the Previous Supervisor Mode (PS) bit of
+ the psr,
-- the cwp is decremented by one (modulo the number of
- register windows) to activate a trap window,
+- the cwp is decremented by one (modulo the number of register windows) to
+ activate a trap window,
-- the PC and nPC are loaded into local register 1 and 2
- (l0 and l1),
+- the PC and nPC are loaded into local register 1 and 2 (l0 and l1),
-- the trap type (tt) field of the Trap Base Register (TBR)
- is set to the appropriate value, and
+- the trap type (tt) field of the Trap Base Register (TBR) is set to the
+ appropriate value, and
-- if the trap is not a reset, then the PC is written with
- the contents of the TBR and the nPC is written with TBR + 4. If
- the trap is a reset, then the PC is set to zero and the nPC is
- set to 4.
+- if the trap is not a reset, then the PC is written with the contents of the
+ TBR and the nPC is written with TBR + 4. If the trap is a reset, then the PC
+ is set to zero and the nPC is set to 4.
-Trap processing on the SPARC has two features which
-are noticeably different than interrupt processing on other
-architectures. First, the value of psr register in effect
-immediately before the trap occurred is not explicitly saved.
-Instead only reversible alterations are made to it. Second, the
-Processor Interrupt Level (pil) is not set to correspond to that
-of the interrupt being processed. When a trap occurs, ALL
-subsequent traps are disabled. In order to safely invoke a
-subroutine during trap handling, traps must be enabled to allow
-for the possibility of register window overflow and underflow
-traps.
+Trap processing on the SPARC has two features which are noticeably different
+than interrupt processing on other architectures. First, the value of psr
+register in effect immediately before the trap occurred is not explicitly
+saved. Instead only reversible alterations are made to it. Second, the
+Processor Interrupt Level (pil) is not set to correspond to that of the
+interrupt being processed. When a trap occurs, ALL subsequent traps are
+disabled. In order to safely invoke a subroutine during trap handling, traps
+must be enabled to allow for the possibility of register window overflow and
+underflow traps.
-If the interrupt handler was installed as an RTEMS
-interrupt handler, then upon receipt of the interrupt, the
-processor passes control to the RTEMS interrupt handler which
-performs the following actions:
+If the interrupt handler was installed as an RTEMS interrupt handler, then upon
+receipt of the interrupt, the processor passes control to the RTEMS interrupt
+handler which performs the following actions:
- saves the state of the interrupted task on it's stack,
-- insures that a register window is available for
- subsequent traps,
+- insures that a register window is available for subsequent traps,
-- if this is the outermost (i.e. non-nested) interrupt,
- then the RTEMS interrupt handler switches from the current stack
- to the interrupt stack,
+- if this is the outermost (i.e. non-nested) interrupt, then the RTEMS
+ interrupt handler switches from the current stack to the interrupt stack,
- enables traps,
- invokes the vectors to a user interrupt service routine (ISR).
-Asynchronous interrupts are ignored while traps are
-disabled. Synchronous traps which occur while traps are
-disabled result in the CPU being forced into an error mode.
+Asynchronous interrupts are ignored while traps are disabled. Synchronous
+traps which occur while traps are disabled result in the CPU being forced into
+an error mode.
-A nested interrupt is processed similarly with the
-exception that the current stack need not be switched to the
-interrupt stack.
+A nested interrupt is processed similarly with the exception that the current
+stack need not be switched to the interrupt stack.
Traps and Register Windows
--------------------------
-One of the register windows must be reserved at all
-times for trap processing. This is critical to the proper
-operation of the trap mechanism in the SPARC architecture. It
-is the responsibility of the trap handler to insure that there
-is a register window available for a subsequent trap before
-re-enabling traps. It is likely that any high level language
-routines invoked by the trap handler (such as a user-provided
-RTEMS interrupt handler) will allocate a new register window.
-The save operation could result in a window overflow trap. This
-trap cannot be correctly processed unless (1) traps are enabled
-and (2) a register window is reserved for traps. Thus, the
-RTEMS interrupt handler insures that a register window is
-available for subsequent traps before enabling traps and
-invoking the user's interrupt handler.
+One of the register windows must be reserved at all times for trap processing.
+This is critical to the proper operation of the trap mechanism in the SPARC
+architecture. It is the responsibility of the trap handler to insure that
+there is a register window available for a subsequent trap before re-enabling
+traps. It is likely that any high level language routines invoked by the trap
+handler (such as a user-provided RTEMS interrupt handler) will allocate a new
+register window. The save operation could result in a window overflow trap.
+This trap cannot be correctly processed unless (1) traps are enabled and (2) a
+register window is reserved for traps. Thus, the RTEMS interrupt handler
+insures that a register window is available for subsequent traps before
+enabling traps and invoking the user's interrupt handler.
Interrupt Levels
----------------
-Sixteen levels (0-15) of interrupt priorities are
-supported by the SPARC architecture with level fifteen (15)
-being the highest priority. Level zero (0) indicates that
-interrupts are fully enabled. Interrupt requests for interrupts
-with priorities less than or equal to the current interrupt mask
-level are ignored. Level fifteen (15) is a non-maskable interrupt
-(NMI), which makes it unsuitable for standard usage since it can
-affect the real-time behaviour by interrupting critical sections
-and spinlocks. Disabling traps stops also the NMI interrupt from
-happening. It can however be used for power-down or other
-critical events.
-
-Although RTEMS supports 256 interrupt levels, the
-SPARC only supports sixteen. RTEMS interrupt levels 0 through
-15 directly correspond to SPARC processor interrupt levels. All
-other RTEMS interrupt levels are undefined and their behavior is
-unpredictable.
-
-Many LEON SPARC v7/v8 systems features an extended interrupt controller
-which adds an extra step of interrupt decoding to allow handling of
-interrupt 16-31. When such an extended interrupt is generated the CPU
-traps into a specific interrupt trap level 1-14 and software reads out from
-the interrupt controller which extended interrupt source actually caused the
-interrupt.
+Sixteen levels (0-15) of interrupt priorities are supported by the SPARC
+architecture with level fifteen (15) being the highest priority. Level
+zero (0) indicates that interrupts are fully enabled. Interrupt requests for
+interrupts with priorities less than or equal to the current interrupt mask
+level are ignored. Level fifteen (15) is a non-maskable interrupt (NMI), which
+makes it unsuitable for standard usage since it can affect the real-time
+behaviour by interrupting critical sections and spinlocks. Disabling traps
+stops also the NMI interrupt from happening. It can however be used for
+power-down or other critical events.
+
+Although RTEMS supports 256 interrupt levels, the SPARC only supports sixteen.
+RTEMS interrupt levels 0 through 15 directly correspond to SPARC processor
+interrupt levels. All other RTEMS interrupt levels are undefined and their
+behavior is unpredictable.
+
+Many LEON SPARC v7/v8 systems features an extended interrupt controller which
+adds an extra step of interrupt decoding to allow handling of interrupt
+16-31. When such an extended interrupt is generated the CPU traps into a
+specific interrupt trap level 1-14 and software reads out from the interrupt
+controller which extended interrupt source actually caused the interrupt.
Disabling of Interrupts by RTEMS
--------------------------------
-During the execution of directive calls, critical
-sections of code may be executed. When these sections are
-encountered, RTEMS disables interrupts to level fifteen (15)
-before the execution of the section and restores them to the
-previous level upon completion of the section. RTEMS has been
-optimized to ensure that interrupts are disabled for less than
-RTEMS_MAXIMUM_DISABLE_PERIOD microseconds on a RTEMS_MAXIMUM_DISABLE_PERIOD_MHZ
-Mhz ERC32 with zero wait states.
-These numbers will vary based the number of wait states and
-processor speed present on the target board.
-\[NOTE: The maximum period with interrupts disabled is hand calculated. This
-calculation was last performed for Release
+During the execution of directive calls, critical sections of code may be
+executed. When these sections are encountered, RTEMS disables interrupts to
+level fifteen (15) before the execution of the section and restores them to the
+previous level upon completion of the section. RTEMS has been optimized to
+ensure that interrupts are disabled for less than RTEMS_MAXIMUM_DISABLE_PERIOD
+microseconds on a RTEMS_MAXIMUM_DISABLE_PERIOD_MHZ Mhz ERC32 with zero wait
+states. These numbers will vary based the number of wait states and processor
+speed present on the target board. [NOTE: The maximum period with interrupts
+disabled is hand calculated. This calculation was last performed for Release
RTEMS_RELEASE_FOR_MAXIMUM_DISABLE_PERIOD.]
-[NOTE: It is thought that the length of time at which
-the processor interrupt level is elevated to fifteen by RTEMS is
-not anywhere near as long as the length of time ALL traps are
-disabled as part of the "flush all register windows" operation.]
-
-Non-maskable interrupts (NMI) cannot be disabled, and
-ISRs which execute at this level MUST NEVER issue RTEMS system
-calls. If a directive is invoked, unpredictable results may
-occur due to the inability of RTEMS to protect its critical
-sections. However, ISRs that make no system calls may safely
-execute as non-maskable interrupts.
-
-Interrupts are disabled or enabled by performing a system call
-to the Operating System reserved software traps 9
-(SPARC_SWTRAP_IRQDIS) or 10 (SPARC_SWTRAP_IRQDIS). The trap is
-generated by the software trap (Ticc) instruction or indirectly
-by calling sparc_disable_interrupts() or sparc_enable_interrupts()
-functions. Disabling interrupts return the previous interrupt level
-(on trap entry) in register G1 and sets PSR.PIL to 15 to disable
-all maskable interrupts. The interrupt level can be restored by
-trapping into the enable interrupt handler with G1 containing the
-new interrupt level.
+[NOTE: It is thought that the length of time at which the processor interrupt
+level is elevated to fifteen by RTEMS is not anywhere near as long as the
+length of time ALL traps are disabled as part of the "flush all register
+windows" operation.]
+
+Non-maskable interrupts (NMI) cannot be disabled, and ISRs which execute at
+this level MUST NEVER issue RTEMS system calls. If a directive is invoked,
+unpredictable results may occur due to the inability of RTEMS to protect its
+critical sections. However, ISRs that make no system calls may safely execute
+as non-maskable interrupts.
+
+Interrupts are disabled or enabled by performing a system call to the Operating
+System reserved software traps 9 (SPARC_SWTRAP_IRQDIS) or 10
+(SPARC_SWTRAP_IRQDIS). The trap is generated by the software trap (Ticc)
+instruction or indirectly by calling sparc_disable_interrupts() or
+sparc_enable_interrupts() functions. Disabling interrupts return the previous
+interrupt level (on trap entry) in register G1 and sets PSR.PIL to 15 to
+disable all maskable interrupts. The interrupt level can be restored by
+trapping into the enable interrupt handler with G1 containing the new interrupt
+level.
Interrupt Stack
---------------
-The SPARC architecture does not provide for a
-dedicated interrupt stack. Thus by default, trap handlers would
-execute on the stack of the RTEMS task which they interrupted.
-This artificially inflates the stack requirements for each task
-since EVERY task stack would have to include enough space to
-account for the worst case interrupt stack requirements in
-addition to it's own worst case usage. RTEMS addresses this
-problem on the SPARC by providing a dedicated interrupt stack
-managed by software.
-
-During system initialization, RTEMS allocates the
-interrupt stack from the Workspace Area. The amount of memory
-allocated for the interrupt stack is determined by the
-interrupt_stack_size field in the CPU Configuration Table. As
-part of processing a non-nested interrupt, RTEMS will switch to
-the interrupt stack before invoking the installed handler.
+The SPARC architecture does not provide for a dedicated interrupt stack. Thus
+by default, trap handlers would execute on the stack of the RTEMS task which
+they interrupted. This artificially inflates the stack requirements for each
+task since EVERY task stack would have to include enough space to account for
+the worst case interrupt stack requirements in addition to it's own worst case
+usage. RTEMS addresses this problem on the SPARC by providing a dedicated
+interrupt stack managed by software.
-.. COMMENT: COPYRIGHT (c) 1988-2002.
-
-.. COMMENT: On-Line Applications Research Corporation (OAR).
-
-.. COMMENT: All rights reserved.
+During system initialization, RTEMS allocates the interrupt stack from the
+Workspace Area. The amount of memory allocated for the interrupt stack is
+determined by the interrupt_stack_size field in the CPU Configuration Table.
+As part of processing a non-nested interrupt, RTEMS will switch to the
+interrupt stack before invoking the installed handler.
Default Fatal Error Processing
==============================
-Upon detection of a fatal error by either the
-application or RTEMS the fatal error manager is invoked. The
-fatal error manager will invoke the user-supplied fatal error
-handlers. If no user-supplied handlers are configured, the
-RTEMS provided default fatal error handler is invoked. If the
-user-supplied fatal error handlers return to the executive the
-default fatal error handler is then invoked. This chapter
-describes the precise operations of the default fatal error
-handler.
+Upon detection of a fatal error by either the application or RTEMS the fatal
+error manager is invoked. The fatal error manager will invoke the
+user-supplied fatal error handlers. If no user-supplied handlers are
+configured, the RTEMS provided default fatal error handler is invoked. If the
+user-supplied fatal error handlers return to the executive the default fatal
+error handler is then invoked. This chapter describes the precise operations
+of the default fatal error handler.
Default Fatal Error Handler Operations
--------------------------------------
-The default fatal error handler which is invoked by
-the fatal_error_occurred directive when there is no user handler
-configured or the user handler returns control to RTEMS.
+The default fatal error handler which is invoked by the fatal_error_occurred
+directive when there is no user handler configured or the user handler returns
+control to RTEMS.
-If the BSP has been configured with ``BSP_POWER_DOWN_AT_FATAL_HALT``
-set to true, the default handler will disable interrupts
-and enter power down mode. If power down mode is not available,
-it goes into an infinite loop to simulate a halt processor instruction.
+If the BSP has been configured with ``BSP_POWER_DOWN_AT_FATAL_HALT`` set to
+true, the default handler will disable interrupts and enter power down mode. If
+power down mode is not available, it goes into an infinite loop to simulate a
+halt processor instruction.
-If ``BSP_POWER_DOWN_AT_FATAL_HALT`` is set to false, the default
-handler will place the value ``1`` in register ``g1``, the
-error source in register ``g2``, and the error code in register``g3``. It will then generate a system error which will
-hand over control to the debugger, simulator, etc.
+If ``BSP_POWER_DOWN_AT_FATAL_HALT`` is set to false, the default handler will
+place the value ``1`` in register ``g1``, the error source in register ``g2``,
+and the error code in register``g3``. It will then generate a system error
+which will hand over control to the debugger, simulator, etc.
Symmetric Multiprocessing
=========================
@@ -852,89 +729,67 @@ Thread-Local Storage
Thread-local storage is supported.
-.. COMMENT: COPYRIGHT (c) 1988-2002.
-
-.. COMMENT: On-Line Applications Research Corporation (OAR).
-
-.. COMMENT: All rights reserved.
-
Board Support Packages
======================
-An RTEMS Board Support Package (BSP) must be designed
-to support a particular processor and target board combination.
-This chapter presents a discussion of SPARC specific BSP issues.
-For more information on developing a BSP, refer to the chapter
-titled Board Support Packages in the RTEMS
-Applications User's Guide.
+An RTEMS Board Support Package (BSP) must be designed to support a particular
+processor and target board combination. This chapter presents a discussion of
+SPARC specific BSP issues. For more information on developing a BSP, refer to
+the chapter titled Board Support Packages in the RTEMS Applications User's
+Guide.
System Reset
------------
-An RTEMS based application is initiated or
-re-initiated when the SPARC processor is reset. When the SPARC
-is reset, the processor performs the following actions:
+An RTEMS based application is initiated or re-initiated when the SPARC
+processor is reset. When the SPARC is reset, the processor performs the
+following actions:
-- the enable trap (ET) of the psr is set to 0 to disable
- traps,
+- the enable trap (ET) of the psr is set to 0 to disable traps,
-- the supervisor bit (S) of the psr is set to 1 to enter
- supervisor mode, and
+- the supervisor bit (S) of the psr is set to 1 to enter supervisor mode, and
- the PC is set 0 and the nPC is set to 4.
-The processor then begins to execute the code at
-location 0. It is important to note that all fields in the psr
-are not explicitly set by the above steps and all other
-registers retain their value from the previous execution mode.
-This is true even of the Trap Base Register (TBR) whose contents
-reflect the last trap which occurred before the reset.
+The processor then begins to execute the code at location 0. It is important
+to note that all fields in the psr are not explicitly set by the above steps
+and all other registers retain their value from the previous execution mode.
+This is true even of the Trap Base Register (TBR) whose contents reflect the
+last trap which occurred before the reset.
Processor Initialization
------------------------
-It is the responsibility of the application's
-initialization code to initialize the TBR and install trap
-handlers for at least the register window overflow and register
-window underflow conditions. Traps should be enabled before
-invoking any subroutines to allow for register window
-management. However, interrupts should be disabled by setting
-the Processor Interrupt Level (pil) field of the psr to 15.
-RTEMS installs it's own Trap Table as part of initialization
-which is initialized with the contents of the Trap Table in
-place when the ``rtems_initialize_executive`` directive was invoked.
-Upon completion of executive initialization, interrupts are
-enabled.
-
-If this SPARC implementation supports on-chip caching
-and this is to be utilized, then it should be enabled during the
-reset application initialization code.
-
-In addition to the requirements described in the
-Board Support Packages chapter of the C
-Applications Users Manual for the reset code
-which is executed before the call to``rtems_initialize_executive``, the SPARC version has the following
+It is the responsibility of the application's initialization code to initialize
+the TBR and install trap handlers for at least the register window overflow and
+register window underflow conditions. Traps should be enabled before invoking
+any subroutines to allow for register window management. However, interrupts
+should be disabled by setting the Processor Interrupt Level (pil) field of the
+psr to 15. RTEMS installs it's own Trap Table as part of initialization which
+is initialized with the contents of the Trap Table in place when the
+``rtems_initialize_executive`` directive was invoked. Upon completion of
+executive initialization, interrupts are enabled.
+
+If this SPARC implementation supports on-chip caching and this is to be
+utilized, then it should be enabled during the reset application initialization
+code.
+
+In addition to the requirements described in the Board Support Packages chapter
+of the C Applications Users Manual for the reset code which is executed before
+the call to``rtems_initialize_executive``, the SPARC version has the following
specific requirements:
-- Must leave the S bit of the status register set so that
- the SPARC remains in the supervisor state.
-
-- Must set stack pointer (sp) such that a minimum stack
- size of MINIMUM_STACK_SIZE bytes is provided for the``rtems_initialize_executive`` directive.
+- Must leave the S bit of the status register set so that the SPARC remains in
+ the supervisor state.
-- Must disable all external interrupts (i.e. set the pil
- to 15).
+- Must set stack pointer (sp) such that a minimum stack size of
+ MINIMUM_STACK_SIZE bytes is provided for the``rtems_initialize_executive``
+ directive.
-- Must enable traps so window overflow and underflow
- conditions can be properly handled.
+- Must disable all external interrupts (i.e. set the pil to 15).
-- Must initialize the SPARC's initial trap table with at
- least trap handlers for register window overflow and register
- window underflow.
-
-.. COMMENT: COPYRIGHT (c) 1988-2002.
-
-.. COMMENT: On-Line Applications Research Corporation (OAR).
-
-.. COMMENT: All rights reserved.
+- Must enable traps so window overflow and underflow conditions can be properly
+ handled.
+- Must initialize the SPARC's initial trap table with at least trap handlers
+ for register window overflow and register window underflow.
diff --git a/cpu_supplement/sparc64.rst b/cpu_supplement/sparc64.rst
index 09842e8..4bc5427 100644
--- a/cpu_supplement/sparc64.rst
+++ b/cpu_supplement/sparc64.rst
@@ -1,5 +1,9 @@
.. comment SPDX-License-Identifier: CC-BY-SA-4.0
+.. COMMENT: COPYRIGHT (c) 1988-2002.
+.. COMMENT: On-Line Applications Research Corporation (OAR).
+.. COMMENT: All rights reserved.
+
SPARC-64 Specific Information
#############################
@@ -21,12 +25,12 @@ The following documents were used in developing the SPARC-64 sun4u port:
- UltraSPARC User's Manual
(http://www.sun.com/microelectronics/manuals/ultrasparc/802-7220-02.pdf)
-- UltraSPARC IIIi Processor (datasheets.chipdb.org/Sun/UltraSparc-IIIi.pdf)
+- UltraSPARC IIIi Processor (http://datasheets.chipdb.org/Sun/UltraSparc-IIIi.pdf)
**sun4v Specific Information**
-sun4v is the subset of the SPARC V9 implementations comprising the
-UltraSPARC T1 or T2 processors.
+sun4v is the subset of the SPARC V9 implementations comprising the UltraSPARC
+T1 or T2 processors.
The following documents were used in developing the SPARC-64 sun4v port:
@@ -36,11 +40,10 @@ The following documents were used in developing the SPARC-64 sun4v port:
- UltraSPARC T1 supplement to UltraSPARC Architecture 2005 Specification
(http://opensparc-t1.sunsource.net/specs/UST1-UASuppl-current-draft-P-EXT.pdf)
-The defining feature that separates the sun4v architecture from its
-predecessor is the existence of a super-privileged hypervisor that
-is responsible for providing virtualized execution environments. The impact
-of the hypervisor on the real-time guarantees available with sun4v has not
-yet been determined.
+The defining feature that separates the sun4v architecture from its predecessor
+is the existence of a super-privileged hypervisor that is responsible for
+providing virtualized execution environments. The impact of the hypervisor on
+the real-time guarantees available with sun4v has not yet been determined.
CPU Model Dependent Features
============================
@@ -48,42 +51,37 @@ CPU Model Dependent Features
CPU Model Feature Flags
-----------------------
-This section presents the set of features which vary across
-SPARC-64 implementations and
-are of importance to RTEMS. The set of CPU model feature macros
-are defined in the file
-cpukit/score/cpu/sparc64/sparc64.h based upon the particular
-CPU model defined on the compilation command line.
+This section presents the set of features which vary across SPARC-64
+implementations and are of importance to RTEMS. The set of CPU model feature
+macros are defined in the file cpukit/score/cpu/sparc64/sparc64.h based upon
+the particular CPU model defined on the compilation command line.
CPU Model Name
~~~~~~~~~~~~~~
-The macro CPU MODEL NAME is a string which designates
-the name of this CPU model.
-For example, for the UltraSPARC T1 SPARC V9 model,
-this macro is set to the string "sun4v".
+The macro CPU MODEL NAME is a string which designates the name of this CPU
+model. For example, for the UltraSPARC T1 SPARC V9 model, this macro is set to
+the string "sun4v".
Floating Point Unit
~~~~~~~~~~~~~~~~~~~
-The macro SPARC_HAS_FPU is set to 1 to indicate that
-this CPU model has a hardware floating point unit and 0
-otherwise.
+The macro SPARC_HAS_FPU is set to 1 to indicate that this CPU model has a
+hardware floating point unit and 0 otherwise.
Number of Register Windows
~~~~~~~~~~~~~~~~~~~~~~~~~~
-The macro SPARC_NUMBER_OF_REGISTER_WINDOWS is set to
-indicate the number of register window sets implemented by this
-CPU model. The SPARC architecture allows for a maximum of
-thirty-two register window sets although most implementations
-only include eight.
+The macro SPARC_NUMBER_OF_REGISTER_WINDOWS is set to indicate the number of
+register window sets implemented by this CPU model. The SPARC architecture
+allows for a maximum of thirty-two register window sets although most
+implementations only include eight.
CPU Model Implementation Notes
------------------------------
-This section describes the implemenation dependencies of the
-CPU Models sun4u and sun4v of the SPARC V9 architecture.
+This section describes the implemenation dependencies of the CPU Models sun4u
+and sun4v of the SPARC V9 architecture.
sun4u Notes
~~~~~~~~~~~
@@ -95,19 +93,12 @@ sun4v Notes
XXX
-.. COMMENT: COPYRIGHT (c) 1988-2002.
-
-.. COMMENT: On-Line Applications Research Corporation (OAR).
-
-.. COMMENT: All rights reserved.
-
Calling Conventions
===================
-Each high-level language compiler generates
-subroutine entry and exit code based upon a set of rules known
-as the compiler's calling convention. These rules address the
-following issues:
+Each high-level language compiler generates subroutine entry and exit code
+based upon a set of rules known as the compiler's calling convention. These
+rules address the following issues:
- register preservation and usage
@@ -122,22 +113,19 @@ target processor are the same, different compilers may use
different calling conventions. As a result, calling conventions
are both processor and compiler dependent.
-The following document also provides some conventions on the
-global register usage in SPARC V9:
-http://developers.sun.com/solaris/articles/sparcv9abi.html
+The following document also provides some conventions on the global register
+usage in SPARC V9: http://developers.sun.com/solaris/articles/sparcv9abi.html
Programming Model
-----------------
-This section discusses the programming model for the
-SPARC architecture.
+This section discusses the programming model for the SPARC architecture.
Non-Floating Point Registers
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-The SPARC architecture defines thirty-two
-non-floating point registers directly visible to the programmer.
-These are divided into four sets:
+The SPARC architecture defines thirty-two non-floating point registers directly
+visible to the programmer. These are divided into four sets:
- input registers
@@ -147,16 +135,13 @@ These are divided into four sets:
- global registers
-Each register is referred to by either two or three
-names in the SPARC reference manuals. First, the registers are
-referred to as r0 through r31 or with the alternate notation
-r[0] through r[31]. Second, each register is a member of one of
-the four sets listed above. Finally, some registers have an
-architecturally defined role in the programming model which
-provides an alternate name. The following table describes the
-mapping between the 32 registers and the register sets:
-
-.. code:: c
+Each register is referred to by either two or three names in the SPARC
+reference manuals. First, the registers are referred to as r0 through r31 or
+with the alternate notation r[0] through r[31]. Second, each register is a
+member of one of the four sets listed above. Finally, some registers have an
+architecturally defined role in the programming model which provides an
+alternate name. The following table describes the mapping between the 32
+registers and the register sets:
+-----------------+----------------+------------------+
| Register Number | Register Names | Description |
@@ -170,11 +155,9 @@ mapping between the 32 registers and the register sets:
| 24 - 31 | i0 - i7 | Input Registers |
+-----------------+----------------+------------------+
-As mentioned above, some of the registers serve
-defined roles in the programming model. The following table
-describes the role of each of these registers:
-
-.. code:: c
+As mentioned above, some of the registers serve defined roles in the
+programming model. The following table describes the role of each of these
+registers:
+---------------+----------------+----------------------+
| Register Name | Alternate Name | Description |
@@ -192,22 +175,19 @@ describes the role of each of these registers:
Floating Point Registers
~~~~~~~~~~~~~~~~~~~~~~~~
-The SPARC V9 architecture includes sixty-four,
-thirty-two bit registers. These registers may be viewed as
-follows:
+The SPARC V9 architecture includes sixty-four, thirty-two bit registers. These
+registers may be viewed as follows:
-- 32 32-bit single precision floating point or integer registers
- (f0, f1, ... f31)
+- 32 32-bit single precision floating point or integer registers (f0, f1,
+ ... f31)
-- 32 64-bit double precision floating point registers (f0, f2,
- f4, ... f62)
+- 32 64-bit double precision floating point registers (f0, f2, f4, ... f62)
-- 16 128-bit extended precision floating point registers (f0, f4,
- f8, ... f60)
+- 16 128-bit extended precision floating point registers (f0, f4, f8, ... f60)
-The floating point state register (fsr) specifies
-the behavior of the floating point unit for rounding, contains
-its condition codes, version specification, and trap information.
+The floating point state register (fsr) specifies the behavior of the floating
+point unit for rounding, contains its condition codes, version specification,
+and trap information.
Special Registers
~~~~~~~~~~~~~~~~~
@@ -215,12 +195,12 @@ Special Registers
The SPARC architecture includes a number of special registers:
*``Ancillary State Registers (ASRs)``*
- The ancillary state registers (ASRs) are optional state registers that
- may be privileged or nonprivileged. ASRs 16-31 are implementation-
- dependent. The SPARC V9 ASRs include: y, ccr, asi, tick, pc, fprs.
- The sun4u ASRs include: pcr, pic, dcr, gsr, softint set, softint clr,
- softint, and tick cmpr. The sun4v ASRs include: pcr, pic, gsr, soft-
- int set, softint clr, softint, tick cmpr, stick, and stick cmpr.
+ The ancillary state registers (ASRs) are optional state registers that may
+ be privileged or nonprivileged. ASRs 16-31 are implementation-
+ dependent. The SPARC V9 ASRs include: y, ccr, asi, tick, pc, fprs. The
+ sun4u ASRs include: pcr, pic, dcr, gsr, softint set, softint clr, softint,
+ and tick cmpr. The sun4v ASRs include: pcr, pic, gsr, soft- int set,
+ softint clr, softint, tick cmpr, stick, and stick cmpr.
*``Processor State Register (pstate)``*
The privileged pstate register contains control fields for the proces-
@@ -232,161 +212,142 @@ The SPARC architecture includes a number of special registers:
accepted.
*``Trap Registers``*
- The trap handling mechanism of the SPARC V9 includes a number of
- registers, including: trap program counter (tpc), trap next pc (tnpc),
- trap state (tstate), trap type (tt), trap base address (tba), and trap
- level (tl).
+ The trap handling mechanism of the SPARC V9 includes a number of registers,
+ including: trap program counter (tpc), trap next pc (tnpc), trap state
+ (tstate), trap type (tt), trap base address (tba), and trap level (tl).
*``Alternate Globals``*
- The AG bit of the pstate register provides access to an alternate set
- of global registers. On sun4v, the AG bit is replaced by the global
- level (gl) register, providing access to at least two and at most eight
- alternate sets of globals.
+ The AG bit of the pstate register provides access to an alternate set of
+ global registers. On sun4v, the AG bit is replaced by the global level (gl)
+ register, providing access to at least two and at most eight alternate sets
+ of globals.
*``Register Window registers``*
- A number of registers assist in register window management.
- These include the current window pointer (cwp), savable windows
- (cansave), restorable windows (canrestore), clean windows (clean-
- win), other windows (otherwin), and window state (wstate).
+ A number of registers assist in register window management. These include
+ the current window pointer (cwp), savable windows (cansave), restorable
+ windows (canrestore), clean windows (clean- win), other windows (otherwin),
+ and window state (wstate).
Register Windows
----------------
-The SPARC architecture includes the concept of
-register windows. An overly simplistic way to think of these
-windows is to imagine them as being an infinite supply of
-"fresh" register sets available for each subroutine to use. In
-reality, they are much more complicated.
-
-The save instruction is used to obtain a new register window.
-This instruction increments the current window pointer, thus
-providing a new set of registers for use. This register set
-includes eight fresh local registers for use exclusively by
-this subroutine. When done with a register set, the restore
-instruction decrements the current window pointer and the
-previous register set is once again available.
-
-The two primary issues complicating the use of register windows
-are that (1) the set of register windows is finite, and (2) some
-registers are shared between adjacent registers windows.
-
-Because the set of register windows is finite, it is
-possible to execute enough save instructions without
-corresponding restore's to consume all of the register windows.
-This is easily accomplished in a high level language because
-each subroutine typically performs a save instruction upon
-entry. Thus having a subroutine call depth greater than the
-number of register windows will result in a window overflow
-condition. The window overflow condition generates a trap which
-must be handled in software. The window overflow trap handler
-is responsible for saving the contents of the oldest register
-window on the program stack.
-
-Similarly, the subroutines will eventually complete
-and begin to perform restore's. If the restore results in the
-need for a register window which has previously been written to
-memory as part of an overflow, then a window underflow condition
-results. Just like the window overflow, the window underflow
-condition must be handled in software by a trap handler. The
-window underflow trap handler is responsible for reloading the
-contents of the register window requested by the restore
-instruction from the program stack.
-
-The cansave, canrestore, otherwin, and cwp are used in conjunction
-to manage the finite set of register windows and detect the window
-overflow and underflow conditions. The first three of these
-registers must satisfy the invariant cansave + canrestore + otherwin =
-nwindow - 2, where nwindow is the number of register windows.
-The cwp contains the index of the register window currently in use.
-RTEMS does not use the cleanwin and otherwin registers.
-
-The save instruction increments the cwp modulo the number of
-register windows, and if cansave is 0 then it also generates a
-window overflow. Similarly, the restore instruction decrements the
-cwp modulo the number of register windows, and if canrestore is 0 then it
-also generates a window underflow.
-
-Unlike with the SPARC model, the SPARC-64 port does not assume that
-a register window is available for a trap. The window overflow
-and underflow conditions are not detected without hardware generating
-the trap. (These conditions can be detected by reading the register window
-registers and doing some simple arithmetic.)
-
-The window overflow and window underflow trap
-handlers are a critical part of the run-time environment for a
-SPARC application. The SPARC architectural specification allows
-for the number of register windows to be any power of two less
-than or equal to 32. The most common choice for SPARC
-implementations appears to be 8 register windows. This results
-in the cwp ranging in value from 0 to 7 on most implementations.
-
-The second complicating factor is the sharing of
-registers between adjacent register windows. While each
-register window has its own set of local registers, the input
-and output registers are shared between adjacent windows. The
-output registers for register window N are the same as the input
-registers for register window ((N + 1) modulo RW) where RW is
-the number of register windows. An alternative way to think of
-this is to remember how parameters are passed to a subroutine on
-the SPARC. The caller loads values into what are its output
-registers. Then after the callee executes a save instruction,
-those parameters are available in its input registers. This is
-a very efficient way to pass parameters as no data is actually
-moved by the save or restore instructions.
+The SPARC architecture includes the concept of register windows. An overly
+simplistic way to think of these windows is to imagine them as being an
+infinite supply of "fresh" register sets available for each subroutine to use.
+In reality, they are much more complicated.
+
+The save instruction is used to obtain a new register window. This instruction
+increments the current window pointer, thus providing a new set of registers
+for use. This register set includes eight fresh local registers for use
+exclusively by this subroutine. When done with a register set, the restore
+instruction decrements the current window pointer and the previous register set
+is once again available.
+
+The two primary issues complicating the use of register windows are that (1)
+the set of register windows is finite, and (2) some registers are shared
+between adjacent registers windows.
+
+Because the set of register windows is finite, it is possible to execute enough
+save instructions without corresponding restore's to consume all of the
+register windows. This is easily accomplished in a high level language because
+each subroutine typically performs a save instruction upon entry. Thus having
+a subroutine call depth greater than the number of register windows will result
+in a window overflow condition. The window overflow condition generates a trap
+which must be handled in software. The window overflow trap handler is
+responsible for saving the contents of the oldest register window on the
+program stack.
+
+Similarly, the subroutines will eventually complete and begin to perform
+restore's. If the restore results in the need for a register window which has
+previously been written to memory as part of an overflow, then a window
+underflow condition results. Just like the window overflow, the window
+underflow condition must be handled in software by a trap handler. The window
+underflow trap handler is responsible for reloading the contents of the
+register window requested by the restore instruction from the program stack.
+
+The cansave, canrestore, otherwin, and cwp are used in conjunction to manage
+the finite set of register windows and detect the window overflow and underflow
+conditions. The first three of these registers must satisfy the invariant
+cansave + canrestore + otherwin = nwindow - 2, where nwindow is the number of
+register windows. The cwp contains the index of the register window currently
+in use. RTEMS does not use the cleanwin and otherwin registers.
+
+The save instruction increments the cwp modulo the number of register windows,
+and if cansave is 0 then it also generates a window overflow. Similarly, the
+restore instruction decrements the cwp modulo the number of register windows,
+and if canrestore is 0 then it also generates a window underflow.
+
+Unlike with the SPARC model, the SPARC-64 port does not assume that a register
+window is available for a trap. The window overflow and underflow conditions
+are not detected without hardware generating the trap. (These conditions can be
+detected by reading the register window registers and doing some simple
+arithmetic.)
+
+The window overflow and window underflow trap handlers are a critical part of
+the run-time environment for a SPARC application. The SPARC architectural
+specification allows for the number of register windows to be any power of two
+less than or equal to 32. The most common choice for SPARC implementations
+appears to be 8 register windows. This results in the cwp ranging in value
+from 0 to 7 on most implementations.
+
+The second complicating factor is the sharing of registers between adjacent
+register windows. While each register window has its own set of local
+registers, the input and output registers are shared between adjacent windows.
+The output registers for register window N are the same as the input registers
+for register window ((N + 1) modulo RW) where RW is the number of register
+windows. An alternative way to think of this is to remember how parameters are
+passed to a subroutine on the SPARC. The caller loads values into what are its
+output registers. Then after the callee executes a save instruction, those
+parameters are available in its input registers. This is a very efficient way
+to pass parameters as no data is actually moved by the save or restore
+instructions.
Call and Return Mechanism
-------------------------
-The SPARC architecture supports a simple yet
-effective call and return mechanism. A subroutine is invoked
-via the call (call) instruction. This instruction places the
-return address in the caller's output register 7 (o7). After
-the callee executes a save instruction, this value is available
-in input register 7 (i7) until the corresponding restore
-instruction is executed.
-
-The callee returns to the caller via a jmp to the
-return address. There is a delay slot following this
-instruction which is commonly used to execute a restore
-instruction - if a register window was allocated by this
-subroutine.
-
-It is important to note that the SPARC subroutine
-call and return mechanism does not automatically save and
-restore any registers. This is accomplished via the save and
-restore instructions which manage the set of registers windows.
-This allows for the compiler to generate leaf-optimized functions
+The SPARC architecture supports a simple yet effective call and return
+mechanism. A subroutine is invoked via the call (call) instruction. This
+instruction places the return address in the caller's output register 7 (o7).
+After the callee executes a save instruction, this value is available in input
+register 7 (i7) until the corresponding restore instruction is executed.
+
+The callee returns to the caller via a jmp to the return address. There is a
+delay slot following this instruction which is commonly used to execute a
+restore instruction - if a register window was allocated by this subroutine.
+
+It is important to note that the SPARC subroutine call and return mechanism
+does not automatically save and restore any registers. This is accomplished
+via the save and restore instructions which manage the set of registers
+windows. This allows for the compiler to generate leaf-optimized functions
that utilize the caller's output registers without using save and restore.
Calling Mechanism
-----------------
-All RTEMS directives are invoked using the regular
-SPARC calling convention via the call instruction.
+All RTEMS directives are invoked using the regular SPARC calling convention via
+the call instruction.
Register Usage
--------------
-As discussed above, the call instruction does not
-automatically save any registers. The save and restore
-instructions are used to allocate and deallocate register
-windows. When a register window is allocated, the new set of
-local registers are available for the exclusive use of the
-subroutine which allocated this register set.
+As discussed above, the call instruction does not automatically save any
+registers. The save and restore instructions are used to allocate and
+deallocate register windows. When a register window is allocated, the new set
+of local registers are available for the exclusive use of the subroutine which
+allocated this register set.
Parameter Passing
-----------------
-RTEMS assumes that arguments are placed in the
-caller's output registers with the first argument in output
-register 0 (o0), the second argument in output register 1 (o1),
-and so forth. Until the callee executes a save instruction, the
-parameters are still visible in the output registers. After the
-callee executes a save instruction, the parameters are visible
-in the corresponding input registers. The following pseudo-code
-illustrates the typical sequence used to call a RTEMS directive
-with three (3) arguments:
-.. code:: c
+RTEMS assumes that arguments are placed in the caller's output registers with
+the first argument in output register 0 (o0), the second argument in output
+register 1 (o1), and so forth. Until the callee executes a save instruction,
+the parameters are still visible in the output registers. After the callee
+executes a save instruction, the parameters are visible in the corresponding
+input registers. The following pseudo-code illustrates the typical sequence
+used to call a RTEMS directive with three (3) arguments:
+
+.. code-block:: c
load third argument into o2
load second argument into o1
@@ -396,44 +357,34 @@ with three (3) arguments:
User-Provided Routines
----------------------
-All user-provided routines invoked by RTEMS, such as
-user extensions, device drivers, and MPCI routines, must also
-adhere to these calling conventions.
-
-.. COMMENT: COPYRIGHT (c) 1988-2002.
-
-.. COMMENT: On-Line Applications Research Corporation (OAR).
-
-.. COMMENT: All rights reserved.
+All user-provided routines invoked by RTEMS, such as user extensions, device
+drivers, and MPCI routines, must also adhere to these calling conventions.
Memory Model
============
-A processor may support any combination of memory
-models ranging from pure physical addressing to complex demand
-paged virtual memory systems. RTEMS supports a flat memory
-model which ranges contiguously over the processor's allowable
-address space. RTEMS does not support segmentation or virtual
-memory of any kind. The appropriate memory model for RTEMS
-provided by the targeted processor and related characteristics
-of that model are described in this chapter.
+A processor may support any combination of memory models ranging from pure
+physical addressing to complex demand paged virtual memory systems. RTEMS
+supports a flat memory model which ranges contiguously over the processor's
+allowable address space. RTEMS does not support segmentation or virtual memory
+of any kind. The appropriate memory model for RTEMS provided by the targeted
+processor and related characteristics of that model are described in this
+chapter.
Flat Memory Model
-----------------
-The SPARC-64 architecture supports a flat 64-bit address space with
-addresses ranging from 0x0000000000000000 to 0xFFFFFFFFFFFFFFFF.
-Each address is represented by a 64-bit value (and an 8-bit address
-space identifider or ASI) and is byte addressable. The address
-may be used to reference a single byte, half-word (2-bytes),
-word (4 bytes), doubleword (8 bytes), or quad-word (16 bytes).
-Memory accesses within this address space are performed
-in big endian fashion by the SPARC. Memory accesses which are not
-properly aligned generate a "memory address not aligned" trap
-(type number 0x34). The following table lists the alignment
-requirements for a variety of data accesses:
+The SPARC-64 architecture supports a flat 64-bit address space with addresses
+ranging from 0x0000000000000000 to 0xFFFFFFFFFFFFFFFF. Each address is
+represented by a 64-bit value (and an 8-bit address space identifider or ASI)
+and is byte addressable. The address may be used to reference a single byte,
+half-word (2-bytes), word (4 bytes), doubleword (8 bytes), or quad-word (16
+bytes). Memory accesses within this address space are performed in big endian
+fashion by the SPARC. Memory accesses which are not properly aligned generate a
+"memory address not aligned" trap (type number 0x34). The following table lists
+the alignment requirements for a variety of data accesses:
-.. code:: c
+.. table::
+--------------+-----------------------+
| Data Type | Alignment Requirement |
@@ -445,60 +396,47 @@ requirements for a variety of data accesses:
| quadword | 16 |
+--------------+-----------------------+
-RTEMS currently does not support any SPARC Memory Management
-Units, therefore, virtual memory or segmentation systems
-involving the SPARC are not supported.
-
-.. COMMENT: COPYRIGHT (c) 1988-2002.
-
-.. COMMENT: On-Line Applications Research Corporation (OAR).
-
-.. COMMENT: All rights reserved.
+RTEMS currently does not support any SPARC Memory Management Units, therefore,
+virtual memory or segmentation systems involving the SPARC are not supported.
Interrupt Processing
====================
-RTEMS and associated documentation uses the terms
-interrupt and vector. In the SPARC architecture, these terms
-correspond to traps and trap type, respectively. The terms will
-be used interchangeably in this manual. Note that in the SPARC manuals,
-interrupts are a subset of the traps that are delivered to software
-interrupt handlers.
+RTEMS and associated documentation uses the terms interrupt and vector. In the
+SPARC architecture, these terms correspond to traps and trap type,
+respectively. The terms will be used interchangeably in this manual. Note that
+in the SPARC manuals, interrupts are a subset of the traps that are delivered
+to software interrupt handlers.
Synchronous Versus Asynchronous Traps
-------------------------------------
-The SPARC architecture includes two classes of traps:
-synchronous (precise) and asynchronous (deferred).
-Asynchronous traps occur when an
-external event interrupts the processor. These traps are not
-associated with any instruction executed by the processor and
-logically occur between instructions. The instruction currently
-in the execute stage of the processor is allowed to complete
-although subsequent instructions are annulled. The return
-address reported by the processor for asynchronous traps is the
-pair of instructions following the current instruction.
-
-Synchronous traps are caused by the actions of an
-instruction. The trap stimulus in this case either occurs
-internally to the processor or is from an external signal that
-was provoked by the instruction. These traps are taken
-immediately and the instruction that caused the trap is aborted
-before any state changes occur in the processor itself. The
-return address reported by the processor for synchronous traps
-is the instruction which caused the trap and the following
-instruction.
+The SPARC architecture includes two classes of traps: synchronous (precise) and
+asynchronous (deferred). Asynchronous traps occur when an external event
+interrupts the processor. These traps are not associated with any instruction
+executed by the processor and logically occur between instructions. The
+instruction currently in the execute stage of the processor is allowed to
+complete although subsequent instructions are annulled. The return address
+reported by the processor for asynchronous traps is the pair of instructions
+following the current instruction.
+
+Synchronous traps are caused by the actions of an instruction. The trap
+stimulus in this case either occurs internally to the processor or is from an
+external signal that was provoked by the instruction. These traps are taken
+immediately and the instruction that caused the trap is aborted before any
+state changes occur in the processor itself. The return address reported by
+the processor for synchronous traps is the instruction which caused the trap
+and the following instruction.
Vectoring of Interrupt Handler
------------------------------
-Upon receipt of an interrupt the SPARC automatically
-performs the following actions:
+Upon receipt of an interrupt the SPARC automatically performs the following
+actions:
-- The trap level is set. This provides access to a fresh set of
- privileged trap-state registers used to save the current state,
- in effect, pushing a frame on the trap stack.
- TL <- TL + 1
+- The trap level is set. This provides access to a fresh set of privileged
+ trap-state registers used to save the current state, in effect, pushing a
+ frame on the trap stack. TL <- TL + 1
- Existing state is preserved
- TSTATE[TL].CCR <- CCR
@@ -536,33 +474,30 @@ performs the following actions:
- where (TL>0) is 0 if TL = 0, and 1 if TL > 0.
In order to safely invoke a subroutine during trap handling, traps must be
-enabled to allow for the possibility of register window overflow and
-underflow traps.
+enabled to allow for the possibility of register window overflow and underflow
+traps.
-If the interrupt handler was installed as an RTEMS
-interrupt handler, then upon receipt of the interrupt, the
-processor passes control to the RTEMS interrupt handler which
-performs the following actions:
+If the interrupt handler was installed as an RTEMS interrupt handler, then upon
+receipt of the interrupt, the processor passes control to the RTEMS interrupt
+handler which performs the following actions:
- saves the state of the interrupted task on it's stack,
- switches the processor to trap level 0,
-- if this is the outermost (i.e. non-nested) interrupt,
- then the RTEMS interrupt handler switches from the current stack
- to the interrupt stack,
+- if this is the outermost (i.e. non-nested) interrupt, then the RTEMS
+ interrupt handler switches from the current stack to the interrupt stack,
- enables traps,
- invokes the vectors to a user interrupt service routine (ISR).
-Asynchronous interrupts are ignored while traps are
-disabled. Synchronous traps which occur while traps are
-disabled may result in the CPU being forced into an error mode.
+Asynchronous interrupts are ignored while traps are disabled. Synchronous
+traps which occur while traps are disabled may result in the CPU being forced
+into an error mode.
-A nested interrupt is processed similarly with the
-exception that the current stack need not be switched to the
-interrupt stack.
+A nested interrupt is processed similarly with the exception that the current
+stack need not be switched to the interrupt stack.
Traps and Register Windows
--------------------------
@@ -572,18 +507,16 @@ XXX
Interrupt Levels
----------------
-Sixteen levels (0-15) of interrupt priorities are
-supported by the SPARC architecture with level fifteen (15)
-being the highest priority. Level zero (0) indicates that
-interrupts are fully enabled. Interrupt requests for interrupts
-with priorities less than or equal to the current interrupt mask
+Sixteen levels (0-15) of interrupt priorities are supported by the SPARC
+architecture with level fifteen (15) being the highest priority. Level
+zero (0) indicates that interrupts are fully enabled. Interrupt requests for
+interrupts with priorities less than or equal to the current interrupt mask
level are ignored.
-Although RTEMS supports 256 interrupt levels, the
-SPARC only supports sixteen. RTEMS interrupt levels 0 through
-15 directly correspond to SPARC processor interrupt levels. All
-other RTEMS interrupt levels are undefined and their behavior is
-unpredictable.
+Although RTEMS supports 256 interrupt levels, the SPARC only supports sixteen.
+RTEMS interrupt levels 0 through 15 directly correspond to SPARC processor
+interrupt levels. All other RTEMS interrupt levels are undefined and their
+behavior is unpredictable.
Disabling of Interrupts by RTEMS
--------------------------------
@@ -593,50 +526,38 @@ XXX
Interrupt Stack
---------------
-The SPARC architecture does not provide for a
-dedicated interrupt stack. Thus by default, trap handlers would
-execute on the stack of the RTEMS task which they interrupted.
-This artificially inflates the stack requirements for each task
-since EVERY task stack would have to include enough space to
-account for the worst case interrupt stack requirements in
-addition to it's own worst case usage. RTEMS addresses this
-problem on the SPARC by providing a dedicated interrupt stack
-managed by software.
-
-During system initialization, RTEMS allocates the
-interrupt stack from the Workspace Area. The amount of memory
-allocated for the interrupt stack is determined by the
-interrupt_stack_size field in the CPU Configuration Table. As
-part of processing a non-nested interrupt, RTEMS will switch to
-the interrupt stack before invoking the installed handler.
+The SPARC architecture does not provide for a dedicated interrupt stack. Thus
+by default, trap handlers would execute on the stack of the RTEMS task which
+they interrupted. This artificially inflates the stack requirements for each
+task since EVERY task stack would have to include enough space to account for
+the worst case interrupt stack requirements in addition to it's own worst case
+usage. RTEMS addresses this problem on the SPARC by providing a dedicated
+interrupt stack managed by software.
-.. COMMENT: COPYRIGHT (c) 1988-2002.
-
-.. COMMENT: On-Line Applications Research Corporation (OAR).
-
-.. COMMENT: All rights reserved.
+During system initialization, RTEMS allocates the interrupt stack from the
+Workspace Area. The amount of memory allocated for the interrupt stack is
+determined by the interrupt_stack_size field in the CPU Configuration Table.
+As part of processing a non-nested interrupt, RTEMS will switch to the
+interrupt stack before invoking the installed handler.
Default Fatal Error Processing
==============================
-Upon detection of a fatal error by either the
-application or RTEMS the fatal error manager is invoked. The
-fatal error manager will invoke the user-supplied fatal error
-handlers. If no user-supplied handlers are configured, the
-RTEMS provided default fatal error handler is invoked. If the
-user-supplied fatal error handlers return to the executive the
-default fatal error handler is then invoked. This chapter
-describes the precise operations of the default fatal error
-handler.
+Upon detection of a fatal error by either the application or RTEMS the fatal
+error manager is invoked. The fatal error manager will invoke the
+user-supplied fatal error handlers. If no user-supplied handlers are
+configured, the RTEMS provided default fatal error handler is invoked. If the
+user-supplied fatal error handlers return to the executive the default fatal
+error handler is then invoked. This chapter describes the precise operations
+of the default fatal error handler.
Default Fatal Error Handler Operations
--------------------------------------
-The default fatal error handler which is invoked by
-the fatal_error_occurred directive when there is no user handler
-configured or the user handler returns control to RTEMS. The
-default fatal error handler disables processor interrupts to
-level 15, places the error code in g1, and goes into an infinite
+The default fatal error handler which is invoked by the fatal_error_occurred
+directive when there is no user handler configured or the user handler returns
+control to RTEMS. The default fatal error handler disables processor
+interrupts to level 15, places the error code in g1, and goes into an infinite
loop to simulate a halt processor instruction.
Symmetric Multiprocessing
@@ -649,30 +570,22 @@ Thread-Local Storage
Thread-local storage is supported.
-.. COMMENT: COPYRIGHT (c) 1988-2002.
-
-.. COMMENT: On-Line Applications Research Corporation (OAR).
-
-.. COMMENT: All rights reserved.
-
Board Support Packages
======================
-An RTEMS Board Support Package (BSP) must be designed
-to support a particular processor and target board combination.
-This chapter presents a discussion of SPARC specific BSP issues.
-For more information on developing a BSP, refer to the chapter
-titled Board Support Packages in the RTEMS
-Applications User's Guide.
+An RTEMS Board Support Package (BSP) must be designed to support a particular
+processor and target board combination. This chapter presents a discussion of
+SPARC specific BSP issues. For more information on developing a BSP, refer to
+the chapter titled Board Support Packages in the RTEMS Applications User's
+Guide.
HelenOS and Open Firmware
-------------------------
-The provided BSPs make use of some bootstrap and low-level hardware code
-of the HelenOS operating system. These files can be found in the shared/helenos
-directory of the sparc64 bsp directory. Consult the sources for more
-detailed information.
+The provided BSPs make use of some bootstrap and low-level hardware code of the
+HelenOS operating system. These files can be found in the shared/helenos
+directory of the sparc64 bsp directory. Consult the sources for more detailed
+information.
The shared BSP code also uses the Open Firmware interface to re-use firmware
code, primarily for console support and default trap handlers.
-
diff --git a/cpu_supplement/superh.rst b/cpu_supplement/superh.rst
index a9a167b..fddf1b1 100644
--- a/cpu_supplement/superh.rst
+++ b/cpu_supplement/superh.rst
@@ -1,28 +1,30 @@
.. comment SPDX-License-Identifier: CC-BY-SA-4.0
+.. COMMENT: COPYRIGHT (c) 1988-2002.
+.. COMMENT: On-Line Applications Research Corporation (OAR).
+.. COMMENT: All rights reserved.
+
SuperH Specific Information
###########################
-This chapter discusses the SuperH architecture dependencies
-in this port of RTEMS. The SuperH family has a wide variety
-of implementations by a wide range of vendors. Consequently,
-there are many, many CPU models within it.
+This chapter discusses the SuperH architecture dependencies in this port of
+RTEMS. The SuperH family has a wide variety of implementations by a wide range
+of vendors. Consequently, there are many, many CPU models within it.
**Architecture Documents**
-For information on the SuperH architecture,
-refer to the following documents available from VENDOR
-(:file:`http//www.XXX.com/`):
+For information on the SuperH architecture, refer to the following documents
+available from VENDOR (http://www.XXX.com/):
- *SuperH Family Reference, VENDOR, PART NUMBER*.
CPU Model Dependent Features
============================
-This chapter presents the set of features which vary
-across SuperH implementations and are of importance to RTEMS.
-The set of CPU model feature macros are defined in the file``cpukit/score/cpu/sh/sh.h`` based upon the particular CPU
-model specified on the compilation command line.
+This chapter presents the set of features which vary across SuperH
+implementations and are of importance to RTEMS. The set of CPU model feature
+macros are defined in the file ``cpukit/score/cpu/sh/sh.h`` based upon the
+particular CPU model specified on the compilation command line.
Another Optional Feature
------------------------
@@ -35,8 +37,8 @@ Calling Conventions
Calling Mechanism
-----------------
-All RTEMS directives are invoked using a ``XXX``
-instruction and return to the user application via the``XXX`` instruction.
+All RTEMS directives are invoked using a ``XXX`` instruction and return to the
+user application via the ``XXX`` instruction.
Register Usage
--------------
@@ -45,12 +47,11 @@ The SH1 has 16 general registers (r0..r15).
- r0..r3 used as general volatile registers
-- r4..r7 used to pass up to 4 arguments to functions, arguments
- above 4 are
+- r4..r7 used to pass up to 4 arguments to functions, arguments above 4 are
passed via the stack)
-- r8..13 caller saved registers (i.e. push them to the stack if you
- need them inside of a function)
+- r8..13 caller saved registers (i.e. push them to the stack if you need them
+ inside of a function)
- r14 frame pointer
@@ -67,43 +68,37 @@ Memory Model
Flat Memory Model
-----------------
-The SuperH family supports a flat 32-bit address
-space with addresses ranging from 0x00000000 to 0xFFFFFFFF (4
-gigabytes). Each address is represented by a 32-bit value and
-is byte addressable. The address may be used to reference a
-single byte, word (2-bytes), or long word (4 bytes). Memory
-accesses within this address space are performed in big endian
-fashion by the processors in this family.
+The SuperH family supports a flat 32-bit address space with addresses ranging
+from 0x00000000 to 0xFFFFFFFF (4 gigabytes). Each address is represented by a
+32-bit value and is byte addressable. The address may be used to reference a
+single byte, word (2-bytes), or long word (4 bytes). Memory accesses within
+this address space are performed in big endian fashion by the processors in
+this family.
-Some of the SuperH family members support virtual memory and
-segmentation. RTEMS does not support virtual memory or
-segmentation on any of the SuperH family members. It is the
-responsibility of the BSP to initialize the mapping for
-a flat memory model.
+Some of the SuperH family members support virtual memory and segmentation.
+RTEMS does not support virtual memory or segmentation on any of the SuperH
+family members. It is the responsibility of the BSP to initialize the mapping
+for a flat memory model.
Interrupt Processing
====================
-Although RTEMS hides many of the processor dependent
-details of interrupt processing, it is important to understand
-how the RTEMS interrupt manager is mapped onto the processor's
-unique architecture. Discussed in this chapter are the MIPS's
-interrupt response and control mechanisms as they pertain to
-RTEMS.
+Although RTEMS hides many of the processor dependent details of interrupt
+processing, it is important to understand how the RTEMS interrupt manager is
+mapped onto the processor's unique architecture. Discussed in this chapter are
+the MIPS's interrupt response and control mechanisms as they pertain to RTEMS.
Vectoring of an Interrupt Handler
---------------------------------
-Upon receipt of an interrupt the XXX family
-members with separate interrupt stacks automatically perform the
-following actions:
+Upon receipt of an interrupt the XXX family members with separate interrupt
+stacks automatically perform the following actions:
- TBD
-A nested interrupt is processed similarly by these
-CPU models with the exception that only a single ISF is placed
-on the interrupt stack and the current stack need not be
-switched.
+A nested interrupt is processed similarly by these CPU models with the
+exception that only a single ISF is placed on the interrupt stack and the
+current stack need not be switched.
Interrupt Levels
----------------
@@ -114,8 +109,8 @@ Default Fatal Error Processing
==============================
The default fatal error handler for this architecture disables processor
-interrupts, places the error code in *XXX*, and executes a ``XXX``
-instruction to simulate a halt processor instruction.
+interrupts, places the error code in *XXX*, and executes a ``XXX`` instruction
+to simulate a halt processor instruction.
Symmetric Multiprocessing
=========================
@@ -143,10 +138,3 @@ Processor Initialization
------------------------
TBD
-
-.. COMMENT: COPYRIGHT (c) 1988-2002.
-
-.. COMMENT: On-Line Applications Research Corporation (OAR).
-
-.. COMMENT: All rights reserved.
-
diff --git a/cpu_supplement/xilinx_microblaze.rst b/cpu_supplement/xilinx_microblaze.rst
index 194f971..4cc2863 100644
--- a/cpu_supplement/xilinx_microblaze.rst
+++ b/cpu_supplement/xilinx_microblaze.rst
@@ -1,5 +1,9 @@
.. comment SPDX-License-Identifier: CC-BY-SA-4.0
+.. COMMENT: COPYRIGHT (c) 1988-2002.
+.. COMMENT: On-Line Applications Research Corporation (OAR).
+.. COMMENT: All rights reserved.
+
Xilinx MicroBlaze Specific Information
######################################
@@ -12,10 +16,3 @@ Thread-Local Storage
====================
Thread-local storage is not implemented.
-
-.. COMMENT: COPYRIGHT (c) 1988-2002.
-
-.. COMMENT: On-Line Applications Research Corporation (OAR).
-
-.. COMMENT: All rights reserved.
-