| Commit message (Collapse) | Author | Age | Files | Lines |
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described in the message following this paragraph. This patch also includes
a mcp750 BSP.
From valette@crf.canon.fr Mon Jun 14 10:03:08 1999
Date: Tue, 18 May 1999 01:30:14 +0200 (CEST)
From: VALETTE Eric <valette@crf.canon.fr>
To: joel@oarcorp.com
Cc: raguet@crf.canon.fr, rtems-snapshots@oarcorp.com, valette@crf.canon.fr
Subject: Questions/Suggestion regarding RTEMS PowerPC code (long)
Dear knowledgeable RTEMS powerpc users,
As some of you may know, I'm currently finalizing a port
of RTEMS on a MCP750 Motorola board. I have done most
of it but have some questions to ask before submitting
the port.
In order to understand some of the changes I have made
or would like to make, maybe it is worth describing the
MCP750 Motorola board.
the MCP750 is a COMPACT PCI powerpc board with :
1) a MPC750 233 MHz processor,
2) a raven bus bridge/PCI controller that
implement an OPENPIC compliant interrupt controller,
3) a VIA 82C586 PCI/ISA bridge that offers a PC
compliant IO for keyboard, serial line, IDE, and
the well known PC 8259 cascaded PIC interrupt
architecture model,
4) a DEC 21140 Ethernet controller,
5) the PPCBUG Motorola firmware in flash,
6) A DEC PCI bridge,
This architecture is common to most Motorola 60x/7xx
board except that :
1) on VME board, the DEC PCI bridge is replaced by
a VME chipset,
2) the VIA 82C586 PCI/ISA bridge is replaced by
another bridge that is almost fully compatible
with the via bridge...
So the port should be a rather close basis for many
60x/7xx motorola board...
On this board, I already have ported Linux 2.2.3 and
use it both as a development and target board.
Now the questions/suggestions I have :
1) EXCEPTION CODE
-------------------
As far as I know exceptions on PPC are handled like
interrupts. I dislike this very much as :
a) Except for the decrementer exception (and
maybe some other on mpc8xx), exceptions are
not recoverable and the handler just need to print
the full context and go to the firmware or debugger...
b) The interrupt switch is only necessary for the
decrementer and external interrupt (at least on
6xx,7xx).
c) The full context for exception is never saved and
thus cannot be used by debugger... I do understand
the most important for interrupts low level code
is to save the minimal context enabling to call C
code for performance reasons. On non recoverable
exception on the other hand, the most important is
to save the maximum information concerning proc status
in order to analyze the reason of the fault. At
least we will need this in order to implement the
port of RGDB on PPC
==> I wrote an API for connecting raw exceptions (and thus
raw interrupts) for mpc750. It should be valid for most
powerpc processors... I hope to find a way to make this coexist
with actual code layout. The code is actually located
in lib/libcpu/powerpc/mpc750 and is thus optional
(provided I write my own version of exec/score/cpu/powerpc/cpu.c ...)
See remark about files/directory layout organization in 4)
2) Current Implementation of ISR low level code
-----------------------------------------------
I do not understand why the MSR EE flags is cleared
again in exec/score/cpu/powerpc/irq_stubs.S
#if (PPC_USE_SPRG)
mfmsr r5
mfspr r6, sprg2
#else
lwz r6,msr_initial(r11)
lis r5,~PPC_MSR_DISABLE_MASK@ha
ori r5,r5,~PPC_MSR_DISABLE_MASK@l
and r6,r6,r5
mfmsr r5
#endif
Reading the doc, when a decrementer interrupt or an
external interrupt is active, the MSR EE flag is already
cleared. BTW if exception/interrupt could occur, it would
trash SRR0 and SRR1. In fact the code may be useful to set
MSR[RI] that re-enables exception processing. BTW I will need
to set other value in MSR to handle interrupts :
a) I want the MSR[IR] and MSR[DR] to be set for
performance reasons and also because I need DBAT
support to have access to PCI memory space as the
interrupt controller is in the PCI space.
Reading the code, I see others have the same kind of request :
/* SCE 980217
*
* We need address translation ON when we call our ISR routine
mtmsr r5
*/
This is just another prof that even the lowest level
IRQ code is fundamentally board dependent and
not simply processor dependent especially when
the processor use external interrupt controller
because it has a single interrupt request line...
Note that if you look at the PPC code high level interrupt
handling code, as the "set_vector" routine that really connects
the interrupt is in the BSP/startup/genpvec.c,
the fact that IRQ handling is BSP specific is DE-FACTO
acknowledged.
I know I have already expressed this and understand that this
would require some heavy change in the code but believe
me you will reach a point where you will not be able
to find a compatible while optimum implementation for low level
interrupt handling code...) In my case this is already true...
So please consider removing low level IRQ handling from
exec/score/cpu/* and only let there exception handling code...
Exceptions are usually only processor dependent and do
not depend on external hardware mechanism to be masked or
acknowledged or re-enabled (there are probably exception but ...)
I have already done this for pc386 bsp but need to make it again.
This time I will even propose an API.
3) R2/R13 manipulation for EABI implementation
----------------------------------------------
I do not understand the handling of r2 and r13 in the
EABI case. The specification for r2 says pointer to sdata2,
sbss2 section => constant. However I do not see -ffixed-r2
passed to any compilation system in make/custom/*
(for info linux does this on PPC).
So either this is a default compiler option when choosing
powerpc-rtems and thus we do not need to do anything with
this register as all the code is compiled with this compiler
and linked together OR this register may be used by rtems code
and then we do not need any special initialization or
handling.
The specification for r13 says pointer to the small data
area. r13 argumentation is the same except that as far
as I know the usage of the small data area requires
specific compiler support so that access to variables is
compiled via loading the LSB in a register and then
using r13 to get full address... It is like a small
memory model and it was present in IBM C compilers.
=> I propose to suppress any specific code for r2 and
r13 in the EABI case.
4) Code layout organization (yes again :-))
-------------------------------------------
I think there are a number of design flaws in the way
the code is for ppc organized and I will try to point them out.
I have been beaten by this again on this new port, and
was beaten last year while modifying code for pc386.
a) exec/score/cpu/* vs lib/libcpu/cpu/*.
I think that too many things are put in exec/score/cpu that
have nothing to do with RTEMS internals but are rather
related to CPU feature.
This include at least :
a) registers access routine (e.g GET_MSR_Value),
b) interrupt masking/unmasking routines,
c) cache_mngt_routine,
d) mmu_mngt_routine,
e) Routines to connect the raw_exception, raw_interrupt
handler,
b) lib/libcpu/cpu/powerpc/*
With a processor family as exuberant as the powerpc family,
and their well known subtle differences (604 vs 750) or
unfortunately majors (8xx vs 60x) the directory structure
is fine (except maybe the names that are not homogeneous)
powerpc
ppc421 mpc821 ...
I only needed to add mpc750. But the fact that libcpu.a was not
produced was a pain and the fact that this organization may
duplicates code is also problematic.
So, except if the support of automake provides a better solution
I would like to propose something like this :
powerpc
mpc421 mpc821 ... mpc750 shared wrapup
with the following rules :
a) "shared" would act as a source container for sources that may
be shared among processors. Needed files would be compiled inside
the processor specific directory using the vpath Makefile
mechanism. "shared" may also contain compilation code
for routine that are really shared and not worth to inline...
(did not found many things so far as registers access routine
ARE WORTH INLINING)... In the case something is compiled there,
it should create libcpushared.a
b) layout under processor specific directory is free provided
that
1)the result of the compilation process exports :
libcpu/powerpc/"PROC"/*.h in $(PROJECT_INCLUDE)/libcpu
2) each processor specific directory creates
a library called libcpuspecific.a
Note that this organization enables to have a file that
is nearly the same than in shared but that must differ
because of processor differences...
c) "wrapup" should create libcpu.a using libcpushared.a
libcpuspecific.a and export it $(PROJECT_INCLUDE)/libcpu
The only thing I have no ideal solution is the way to put shared
definitions in "shared" and only processor specific definition
in "proc". To give a concrete example, most MSR bit definition
are shared among PPC processors and only some differs. if we create
a single msr.h in shared it will have ifdef. If in msr.h we
include libcpu/msr_c.h we will need to have it in each prowerpc
specific directory (even empty). Opinions are welcomed ...
Note that a similar mechanism exist in libbsp/i386 that also
contains a shared directory that is used by several bsp
like pc386 and i386ex and a similar wrapup mechanism...
NB: I have done this for mpc750 and other processors could just use
similar Makefiles...
c) The exec/score/cpu/powerpc directory layout.
I think the directory layout should be the same than the
libcpu/powerpc. As it is not, there are a lot of ifdefs
inside the code... And of course low level interrupt handling
code should be removed...
Besides that I do not understand why
1) things are compiled in the wrap directory,
2) some includes are moved to rtems/score,
I think the "preinstall" mechanism enables to put
everything in the current directory (or better in a per processor
directory),
5) Interrupt handling API
-------------------------
Again :-). But I think that using all the features the PIC
offers is a MUST for RT system. I already explained in the
prologue of this (long and probably boring) mail that the MCP750
boards offers an OPENPIC compliant architecture and that
the VIA 82586 PCI/ISA bridge offers a PC compatible IO and
PIC mapping. Here is a logical view of the RAVEN/VIA 82586
interrupt mapping :
--------- 0 ------
| OPEN | <-----|8259|
| PIC | | | 2 ------
|(RAVEN)| | | <-----|8259|
| | | | | | 11
| | | | | | <----
| | | | | |
| | | | | |
--------- ------ | |
^ ------
| VIA PCI/ISA bridge
| x
-------- PCI interrupts
OPENPIC offers interrupt priorities among PCI interrupts
and interrupt selective masking. The 8259 offers the same kind
of feature. With actual powerpc interrupt code :
1) there is no way to specify priorities among
interrupts handler. This is REALLY a bad thing.
For me it is as importnat as having priorities
for threads...
2) for my implementation, each ISR should
contain the code that acknowledge the RAVEN
and 8259 cascade, modify interrupt mask on both
chips, and reenable interrupt at processor level,
..., restore then on interrupt return,.... This code
is actually similar to code located in some
genpvec.c powerpc files,
3) I must update _ISR_Nesting_level because
irq.inl use it...
4) the libchip code connects the ISR via set_vector
but the libchip handler code does not contain any code to
manipulate external interrupt controller hardware
in order to acknoledge the interrupt or re-enable
them (except for the target hardware of course)
So this code is broken unless set_vector adds an
additionnal prologue/epilogue before calling/returning
from in order to acknoledge/mask the raven and the
8259 PICS... => Anyway already EACH BSP MUST REWRITE
PART OF INTERRUPT HANDLING CODE TO CORRECTLY IMPLEMENT
SET_VECTOR.
I would rather offer an API similar to the one provided
in libbsp/i386/shared/irq/irq.h so that :
1) Once the driver supplied methods is called the
only things the ISR has to do is to worry about the
external hardware that triggered the interrupt.
Everything on openpic/VIA/processor would have been
done by the low levels (same things as set-vector)
2) The caller will need to supply the on/off/isOn
routine that are fundamental to correctly implements
debuggers/performance monitoring is a portable way
3) A globally configurable interrupt priorities
mechanism...
I have nothing against providing a compatible
set_vector just to make libchip happy but
as I have already explained in other
mails (months ago), I really think that the ISR
connection should be handled by the BSP and that no
code containing irq connection should exist the
rtems generic layers... Thus I really dislike
libchip on this aspect because in a long term
it will force to adopt the less reach API
for interrupt handling that exists (set_vector).
Additional note : I think the _ISR_Is_in_progress()
inline routine should be :
1) Put in a processor specific section,
2) Should not rely on a global variable,
As :
a) on symmetric MP, there is one interrupt level
per CPU,
b) On processor that have an ISP (e,g 68040),
this variable is useless (MSR bit testing could
be used)
c) On PPC, instead of using the address of the
variable via __CPU_IRQ_info.Nest_level a dedicated
SPR could be used.
NOTE: most of this is also true for _Thread_Dispatch_disable_level
END NOTE
--------
Please do not take what I said in the mail as a criticism for
anyone who submitted ppc code. Any code present helped me
a lot understanding PPC behavior. I just wanted by this
mail to :
1) try to better understand the actual code,
2) propose concrete ways of enhancing current code
by providing an alternative implementation for MCP750. I
will make my best effort to try to brake nothing but this
is actually hard due to the file layout organisation.
3) make understandable some changes I will probably make
if joel let me do them :-)
Any comments/objections are welcomed as usual.
--
__
/ ` Eric Valette
/-- __ o _. Canon CRF
(___, / (_(_(__ Rue de la touche lambert
35517 Cesson-Sevigne Cedex
FRANCE
Tel: +33 (0)2 99 87 68 91 Fax: +33 (0)2 99 84 11 30
E-mail: valette@crf.canon.fr
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described in the message following this paragraph. This patch also includes
a mcp750 BSP.
From valette@crf.canon.fr Mon Jun 14 10:03:08 1999
Date: Tue, 18 May 1999 01:30:14 +0200 (CEST)
From: VALETTE Eric <valette@crf.canon.fr>
To: joel@oarcorp.com
Cc: raguet@crf.canon.fr, rtems-snapshots@oarcorp.com, valette@crf.canon.fr
Subject: Questions/Suggestion regarding RTEMS PowerPC code (long)
Dear knowledgeable RTEMS powerpc users,
As some of you may know, I'm currently finalizing a port
of RTEMS on a MCP750 Motorola board. I have done most
of it but have some questions to ask before submitting
the port.
In order to understand some of the changes I have made
or would like to make, maybe it is worth describing the
MCP750 Motorola board.
the MCP750 is a COMPACT PCI powerpc board with :
1) a MPC750 233 MHz processor,
2) a raven bus bridge/PCI controller that
implement an OPENPIC compliant interrupt controller,
3) a VIA 82C586 PCI/ISA bridge that offers a PC
compliant IO for keyboard, serial line, IDE, and
the well known PC 8259 cascaded PIC interrupt
architecture model,
4) a DEC 21140 Ethernet controller,
5) the PPCBUG Motorola firmware in flash,
6) A DEC PCI bridge,
This architecture is common to most Motorola 60x/7xx
board except that :
1) on VME board, the DEC PCI bridge is replaced by
a VME chipset,
2) the VIA 82C586 PCI/ISA bridge is replaced by
another bridge that is almost fully compatible
with the via bridge...
So the port should be a rather close basis for many
60x/7xx motorola board...
On this board, I already have ported Linux 2.2.3 and
use it both as a development and target board.
Now the questions/suggestions I have :
1) EXCEPTION CODE
-------------------
As far as I know exceptions on PPC are handled like
interrupts. I dislike this very much as :
a) Except for the decrementer exception (and
maybe some other on mpc8xx), exceptions are
not recoverable and the handler just need to print
the full context and go to the firmware or debugger...
b) The interrupt switch is only necessary for the
decrementer and external interrupt (at least on
6xx,7xx).
c) The full context for exception is never saved and
thus cannot be used by debugger... I do understand
the most important for interrupts low level code
is to save the minimal context enabling to call C
code for performance reasons. On non recoverable
exception on the other hand, the most important is
to save the maximum information concerning proc status
in order to analyze the reason of the fault. At
least we will need this in order to implement the
port of RGDB on PPC
==> I wrote an API for connecting raw exceptions (and thus
raw interrupts) for mpc750. It should be valid for most
powerpc processors... I hope to find a way to make this coexist
with actual code layout. The code is actually located
in lib/libcpu/powerpc/mpc750 and is thus optional
(provided I write my own version of exec/score/cpu/powerpc/cpu.c ...)
See remark about files/directory layout organization in 4)
2) Current Implementation of ISR low level code
-----------------------------------------------
I do not understand why the MSR EE flags is cleared
again in exec/score/cpu/powerpc/irq_stubs.S
#if (PPC_USE_SPRG)
mfmsr r5
mfspr r6, sprg2
#else
lwz r6,msr_initial(r11)
lis r5,~PPC_MSR_DISABLE_MASK@ha
ori r5,r5,~PPC_MSR_DISABLE_MASK@l
and r6,r6,r5
mfmsr r5
#endif
Reading the doc, when a decrementer interrupt or an
external interrupt is active, the MSR EE flag is already
cleared. BTW if exception/interrupt could occur, it would
trash SRR0 and SRR1. In fact the code may be useful to set
MSR[RI] that re-enables exception processing. BTW I will need
to set other value in MSR to handle interrupts :
a) I want the MSR[IR] and MSR[DR] to be set for
performance reasons and also because I need DBAT
support to have access to PCI memory space as the
interrupt controller is in the PCI space.
Reading the code, I see others have the same kind of request :
/* SCE 980217
*
* We need address translation ON when we call our ISR routine
mtmsr r5
*/
This is just another prof that even the lowest level
IRQ code is fundamentally board dependent and
not simply processor dependent especially when
the processor use external interrupt controller
because it has a single interrupt request line...
Note that if you look at the PPC code high level interrupt
handling code, as the "set_vector" routine that really connects
the interrupt is in the BSP/startup/genpvec.c,
the fact that IRQ handling is BSP specific is DE-FACTO
acknowledged.
I know I have already expressed this and understand that this
would require some heavy change in the code but believe
me you will reach a point where you will not be able
to find a compatible while optimum implementation for low level
interrupt handling code...) In my case this is already true...
So please consider removing low level IRQ handling from
exec/score/cpu/* and only let there exception handling code...
Exceptions are usually only processor dependent and do
not depend on external hardware mechanism to be masked or
acknowledged or re-enabled (there are probably exception but ...)
I have already done this for pc386 bsp but need to make it again.
This time I will even propose an API.
3) R2/R13 manipulation for EABI implementation
----------------------------------------------
I do not understand the handling of r2 and r13 in the
EABI case. The specification for r2 says pointer to sdata2,
sbss2 section => constant. However I do not see -ffixed-r2
passed to any compilation system in make/custom/*
(for info linux does this on PPC).
So either this is a default compiler option when choosing
powerpc-rtems and thus we do not need to do anything with
this register as all the code is compiled with this compiler
and linked together OR this register may be used by rtems code
and then we do not need any special initialization or
handling.
The specification for r13 says pointer to the small data
area. r13 argumentation is the same except that as far
as I know the usage of the small data area requires
specific compiler support so that access to variables is
compiled via loading the LSB in a register and then
using r13 to get full address... It is like a small
memory model and it was present in IBM C compilers.
=> I propose to suppress any specific code for r2 and
r13 in the EABI case.
4) Code layout organization (yes again :-))
-------------------------------------------
I think there are a number of design flaws in the way
the code is for ppc organized and I will try to point them out.
I have been beaten by this again on this new port, and
was beaten last year while modifying code for pc386.
a) exec/score/cpu/* vs lib/libcpu/cpu/*.
I think that too many things are put in exec/score/cpu that
have nothing to do with RTEMS internals but are rather
related to CPU feature.
This include at least :
a) registers access routine (e.g GET_MSR_Value),
b) interrupt masking/unmasking routines,
c) cache_mngt_routine,
d) mmu_mngt_routine,
e) Routines to connect the raw_exception, raw_interrupt
handler,
b) lib/libcpu/cpu/powerpc/*
With a processor family as exuberant as the powerpc family,
and their well known subtle differences (604 vs 750) or
unfortunately majors (8xx vs 60x) the directory structure
is fine (except maybe the names that are not homogeneous)
powerpc
ppc421 mpc821 ...
I only needed to add mpc750. But the fact that libcpu.a was not
produced was a pain and the fact that this organization may
duplicates code is also problematic.
So, except if the support of automake provides a better solution
I would like to propose something like this :
powerpc
mpc421 mpc821 ... mpc750 shared wrapup
with the following rules :
a) "shared" would act as a source container for sources that may
be shared among processors. Needed files would be compiled inside
the processor specific directory using the vpath Makefile
mechanism. "shared" may also contain compilation code
for routine that are really shared and not worth to inline...
(did not found many things so far as registers access routine
ARE WORTH INLINING)... In the case something is compiled there,
it should create libcpushared.a
b) layout under processor specific directory is free provided
that
1)the result of the compilation process exports :
libcpu/powerpc/"PROC"/*.h in $(PROJECT_INCLUDE)/libcpu
2) each processor specific directory creates
a library called libcpuspecific.a
Note that this organization enables to have a file that
is nearly the same than in shared but that must differ
because of processor differences...
c) "wrapup" should create libcpu.a using libcpushared.a
libcpuspecific.a and export it $(PROJECT_INCLUDE)/libcpu
The only thing I have no ideal solution is the way to put shared
definitions in "shared" and only processor specific definition
in "proc". To give a concrete example, most MSR bit definition
are shared among PPC processors and only some differs. if we create
a single msr.h in shared it will have ifdef. If in msr.h we
include libcpu/msr_c.h we will need to have it in each prowerpc
specific directory (even empty). Opinions are welcomed ...
Note that a similar mechanism exist in libbsp/i386 that also
contains a shared directory that is used by several bsp
like pc386 and i386ex and a similar wrapup mechanism...
NB: I have done this for mpc750 and other processors could just use
similar Makefiles...
c) The exec/score/cpu/powerpc directory layout.
I think the directory layout should be the same than the
libcpu/powerpc. As it is not, there are a lot of ifdefs
inside the code... And of course low level interrupt handling
code should be removed...
Besides that I do not understand why
1) things are compiled in the wrap directory,
2) some includes are moved to rtems/score,
I think the "preinstall" mechanism enables to put
everything in the current directory (or better in a per processor
directory),
5) Interrupt handling API
-------------------------
Again :-). But I think that using all the features the PIC
offers is a MUST for RT system. I already explained in the
prologue of this (long and probably boring) mail that the MCP750
boards offers an OPENPIC compliant architecture and that
the VIA 82586 PCI/ISA bridge offers a PC compatible IO and
PIC mapping. Here is a logical view of the RAVEN/VIA 82586
interrupt mapping :
--------- 0 ------
| OPEN | <-----|8259|
| PIC | | | 2 ------
|(RAVEN)| | | <-----|8259|
| | | | | | 11
| | | | | | <----
| | | | | |
| | | | | |
--------- ------ | |
^ ------
| VIA PCI/ISA bridge
| x
-------- PCI interrupts
OPENPIC offers interrupt priorities among PCI interrupts
and interrupt selective masking. The 8259 offers the same kind
of feature. With actual powerpc interrupt code :
1) there is no way to specify priorities among
interrupts handler. This is REALLY a bad thing.
For me it is as importnat as having priorities
for threads...
2) for my implementation, each ISR should
contain the code that acknowledge the RAVEN
and 8259 cascade, modify interrupt mask on both
chips, and reenable interrupt at processor level,
..., restore then on interrupt return,.... This code
is actually similar to code located in some
genpvec.c powerpc files,
3) I must update _ISR_Nesting_level because
irq.inl use it...
4) the libchip code connects the ISR via set_vector
but the libchip handler code does not contain any code to
manipulate external interrupt controller hardware
in order to acknoledge the interrupt or re-enable
them (except for the target hardware of course)
So this code is broken unless set_vector adds an
additionnal prologue/epilogue before calling/returning
from in order to acknoledge/mask the raven and the
8259 PICS... => Anyway already EACH BSP MUST REWRITE
PART OF INTERRUPT HANDLING CODE TO CORRECTLY IMPLEMENT
SET_VECTOR.
I would rather offer an API similar to the one provided
in libbsp/i386/shared/irq/irq.h so that :
1) Once the driver supplied methods is called the
only things the ISR has to do is to worry about the
external hardware that triggered the interrupt.
Everything on openpic/VIA/processor would have been
done by the low levels (same things as set-vector)
2) The caller will need to supply the on/off/isOn
routine that are fundamental to correctly implements
debuggers/performance monitoring is a portable way
3) A globally configurable interrupt priorities
mechanism...
I have nothing against providing a compatible
set_vector just to make libchip happy but
as I have already explained in other
mails (months ago), I really think that the ISR
connection should be handled by the BSP and that no
code containing irq connection should exist the
rtems generic layers... Thus I really dislike
libchip on this aspect because in a long term
it will force to adopt the less reach API
for interrupt handling that exists (set_vector).
Additional note : I think the _ISR_Is_in_progress()
inline routine should be :
1) Put in a processor specific section,
2) Should not rely on a global variable,
As :
a) on symmetric MP, there is one interrupt level
per CPU,
b) On processor that have an ISP (e,g 68040),
this variable is useless (MSR bit testing could
be used)
c) On PPC, instead of using the address of the
variable via __CPU_IRQ_info.Nest_level a dedicated
SPR could be used.
NOTE: most of this is also true for _Thread_Dispatch_disable_level
END NOTE
--------
Please do not take what I said in the mail as a criticism for
anyone who submitted ppc code. Any code present helped me
a lot understanding PPC behavior. I just wanted by this
mail to :
1) try to better understand the actual code,
2) propose concrete ways of enhancing current code
by providing an alternative implementation for MCP750. I
will make my best effort to try to brake nothing but this
is actually hard due to the file layout organisation.
3) make understandable some changes I will probably make
if joel let me do them :-)
Any comments/objections are welcomed as usual.
--
__
/ ` Eric Valette
/-- __ o _. Canon CRF
(___, / (_(_(__ Rue de la touche lambert
35517 Cesson-Sevigne Cedex
FRANCE
Tel: +33 (0)2 99 87 68 91 Fax: +33 (0)2 99 84 11 30
E-mail: valette@crf.canon.fr
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described in the message following this paragraph. This patch also includes
a mcp750 BSP.
From valette@crf.canon.fr Mon Jun 14 10:03:08 1999
Date: Tue, 18 May 1999 01:30:14 +0200 (CEST)
From: VALETTE Eric <valette@crf.canon.fr>
To: joel@oarcorp.com
Cc: raguet@crf.canon.fr, rtems-snapshots@oarcorp.com, valette@crf.canon.fr
Subject: Questions/Suggestion regarding RTEMS PowerPC code (long)
Dear knowledgeable RTEMS powerpc users,
As some of you may know, I'm currently finalizing a port
of RTEMS on a MCP750 Motorola board. I have done most
of it but have some questions to ask before submitting
the port.
In order to understand some of the changes I have made
or would like to make, maybe it is worth describing the
MCP750 Motorola board.
the MCP750 is a COMPACT PCI powerpc board with :
1) a MPC750 233 MHz processor,
2) a raven bus bridge/PCI controller that
implement an OPENPIC compliant interrupt controller,
3) a VIA 82C586 PCI/ISA bridge that offers a PC
compliant IO for keyboard, serial line, IDE, and
the well known PC 8259 cascaded PIC interrupt
architecture model,
4) a DEC 21140 Ethernet controller,
5) the PPCBUG Motorola firmware in flash,
6) A DEC PCI bridge,
This architecture is common to most Motorola 60x/7xx
board except that :
1) on VME board, the DEC PCI bridge is replaced by
a VME chipset,
2) the VIA 82C586 PCI/ISA bridge is replaced by
another bridge that is almost fully compatible
with the via bridge...
So the port should be a rather close basis for many
60x/7xx motorola board...
On this board, I already have ported Linux 2.2.3 and
use it both as a development and target board.
Now the questions/suggestions I have :
1) EXCEPTION CODE
-------------------
As far as I know exceptions on PPC are handled like
interrupts. I dislike this very much as :
a) Except for the decrementer exception (and
maybe some other on mpc8xx), exceptions are
not recoverable and the handler just need to print
the full context and go to the firmware or debugger...
b) The interrupt switch is only necessary for the
decrementer and external interrupt (at least on
6xx,7xx).
c) The full context for exception is never saved and
thus cannot be used by debugger... I do understand
the most important for interrupts low level code
is to save the minimal context enabling to call C
code for performance reasons. On non recoverable
exception on the other hand, the most important is
to save the maximum information concerning proc status
in order to analyze the reason of the fault. At
least we will need this in order to implement the
port of RGDB on PPC
==> I wrote an API for connecting raw exceptions (and thus
raw interrupts) for mpc750. It should be valid for most
powerpc processors... I hope to find a way to make this coexist
with actual code layout. The code is actually located
in lib/libcpu/powerpc/mpc750 and is thus optional
(provided I write my own version of exec/score/cpu/powerpc/cpu.c ...)
See remark about files/directory layout organization in 4)
2) Current Implementation of ISR low level code
-----------------------------------------------
I do not understand why the MSR EE flags is cleared
again in exec/score/cpu/powerpc/irq_stubs.S
#if (PPC_USE_SPRG)
mfmsr r5
mfspr r6, sprg2
#else
lwz r6,msr_initial(r11)
lis r5,~PPC_MSR_DISABLE_MASK@ha
ori r5,r5,~PPC_MSR_DISABLE_MASK@l
and r6,r6,r5
mfmsr r5
#endif
Reading the doc, when a decrementer interrupt or an
external interrupt is active, the MSR EE flag is already
cleared. BTW if exception/interrupt could occur, it would
trash SRR0 and SRR1. In fact the code may be useful to set
MSR[RI] that re-enables exception processing. BTW I will need
to set other value in MSR to handle interrupts :
a) I want the MSR[IR] and MSR[DR] to be set for
performance reasons and also because I need DBAT
support to have access to PCI memory space as the
interrupt controller is in the PCI space.
Reading the code, I see others have the same kind of request :
/* SCE 980217
*
* We need address translation ON when we call our ISR routine
mtmsr r5
*/
This is just another prof that even the lowest level
IRQ code is fundamentally board dependent and
not simply processor dependent especially when
the processor use external interrupt controller
because it has a single interrupt request line...
Note that if you look at the PPC code high level interrupt
handling code, as the "set_vector" routine that really connects
the interrupt is in the BSP/startup/genpvec.c,
the fact that IRQ handling is BSP specific is DE-FACTO
acknowledged.
I know I have already expressed this and understand that this
would require some heavy change in the code but believe
me you will reach a point where you will not be able
to find a compatible while optimum implementation for low level
interrupt handling code...) In my case this is already true...
So please consider removing low level IRQ handling from
exec/score/cpu/* and only let there exception handling code...
Exceptions are usually only processor dependent and do
not depend on external hardware mechanism to be masked or
acknowledged or re-enabled (there are probably exception but ...)
I have already done this for pc386 bsp but need to make it again.
This time I will even propose an API.
3) R2/R13 manipulation for EABI implementation
----------------------------------------------
I do not understand the handling of r2 and r13 in the
EABI case. The specification for r2 says pointer to sdata2,
sbss2 section => constant. However I do not see -ffixed-r2
passed to any compilation system in make/custom/*
(for info linux does this on PPC).
So either this is a default compiler option when choosing
powerpc-rtems and thus we do not need to do anything with
this register as all the code is compiled with this compiler
and linked together OR this register may be used by rtems code
and then we do not need any special initialization or
handling.
The specification for r13 says pointer to the small data
area. r13 argumentation is the same except that as far
as I know the usage of the small data area requires
specific compiler support so that access to variables is
compiled via loading the LSB in a register and then
using r13 to get full address... It is like a small
memory model and it was present in IBM C compilers.
=> I propose to suppress any specific code for r2 and
r13 in the EABI case.
4) Code layout organization (yes again :-))
-------------------------------------------
I think there are a number of design flaws in the way
the code is for ppc organized and I will try to point them out.
I have been beaten by this again on this new port, and
was beaten last year while modifying code for pc386.
a) exec/score/cpu/* vs lib/libcpu/cpu/*.
I think that too many things are put in exec/score/cpu that
have nothing to do with RTEMS internals but are rather
related to CPU feature.
This include at least :
a) registers access routine (e.g GET_MSR_Value),
b) interrupt masking/unmasking routines,
c) cache_mngt_routine,
d) mmu_mngt_routine,
e) Routines to connect the raw_exception, raw_interrupt
handler,
b) lib/libcpu/cpu/powerpc/*
With a processor family as exuberant as the powerpc family,
and their well known subtle differences (604 vs 750) or
unfortunately majors (8xx vs 60x) the directory structure
is fine (except maybe the names that are not homogeneous)
powerpc
ppc421 mpc821 ...
I only needed to add mpc750. But the fact that libcpu.a was not
produced was a pain and the fact that this organization may
duplicates code is also problematic.
So, except if the support of automake provides a better solution
I would like to propose something like this :
powerpc
mpc421 mpc821 ... mpc750 shared wrapup
with the following rules :
a) "shared" would act as a source container for sources that may
be shared among processors. Needed files would be compiled inside
the processor specific directory using the vpath Makefile
mechanism. "shared" may also contain compilation code
for routine that are really shared and not worth to inline...
(did not found many things so far as registers access routine
ARE WORTH INLINING)... In the case something is compiled there,
it should create libcpushared.a
b) layout under processor specific directory is free provided
that
1)the result of the compilation process exports :
libcpu/powerpc/"PROC"/*.h in $(PROJECT_INCLUDE)/libcpu
2) each processor specific directory creates
a library called libcpuspecific.a
Note that this organization enables to have a file that
is nearly the same than in shared but that must differ
because of processor differences...
c) "wrapup" should create libcpu.a using libcpushared.a
libcpuspecific.a and export it $(PROJECT_INCLUDE)/libcpu
The only thing I have no ideal solution is the way to put shared
definitions in "shared" and only processor specific definition
in "proc". To give a concrete example, most MSR bit definition
are shared among PPC processors and only some differs. if we create
a single msr.h in shared it will have ifdef. If in msr.h we
include libcpu/msr_c.h we will need to have it in each prowerpc
specific directory (even empty). Opinions are welcomed ...
Note that a similar mechanism exist in libbsp/i386 that also
contains a shared directory that is used by several bsp
like pc386 and i386ex and a similar wrapup mechanism...
NB: I have done this for mpc750 and other processors could just use
similar Makefiles...
c) The exec/score/cpu/powerpc directory layout.
I think the directory layout should be the same than the
libcpu/powerpc. As it is not, there are a lot of ifdefs
inside the code... And of course low level interrupt handling
code should be removed...
Besides that I do not understand why
1) things are compiled in the wrap directory,
2) some includes are moved to rtems/score,
I think the "preinstall" mechanism enables to put
everything in the current directory (or better in a per processor
directory),
5) Interrupt handling API
-------------------------
Again :-). But I think that using all the features the PIC
offers is a MUST for RT system. I already explained in the
prologue of this (long and probably boring) mail that the MCP750
boards offers an OPENPIC compliant architecture and that
the VIA 82586 PCI/ISA bridge offers a PC compatible IO and
PIC mapping. Here is a logical view of the RAVEN/VIA 82586
interrupt mapping :
--------- 0 ------
| OPEN | <-----|8259|
| PIC | | | 2 ------
|(RAVEN)| | | <-----|8259|
| | | | | | 11
| | | | | | <----
| | | | | |
| | | | | |
--------- ------ | |
^ ------
| VIA PCI/ISA bridge
| x
-------- PCI interrupts
OPENPIC offers interrupt priorities among PCI interrupts
and interrupt selective masking. The 8259 offers the same kind
of feature. With actual powerpc interrupt code :
1) there is no way to specify priorities among
interrupts handler. This is REALLY a bad thing.
For me it is as importnat as having priorities
for threads...
2) for my implementation, each ISR should
contain the code that acknowledge the RAVEN
and 8259 cascade, modify interrupt mask on both
chips, and reenable interrupt at processor level,
..., restore then on interrupt return,.... This code
is actually similar to code located in some
genpvec.c powerpc files,
3) I must update _ISR_Nesting_level because
irq.inl use it...
4) the libchip code connects the ISR via set_vector
but the libchip handler code does not contain any code to
manipulate external interrupt controller hardware
in order to acknoledge the interrupt or re-enable
them (except for the target hardware of course)
So this code is broken unless set_vector adds an
additionnal prologue/epilogue before calling/returning
from in order to acknoledge/mask the raven and the
8259 PICS... => Anyway already EACH BSP MUST REWRITE
PART OF INTERRUPT HANDLING CODE TO CORRECTLY IMPLEMENT
SET_VECTOR.
I would rather offer an API similar to the one provided
in libbsp/i386/shared/irq/irq.h so that :
1) Once the driver supplied methods is called the
only things the ISR has to do is to worry about the
external hardware that triggered the interrupt.
Everything on openpic/VIA/processor would have been
done by the low levels (same things as set-vector)
2) The caller will need to supply the on/off/isOn
routine that are fundamental to correctly implements
debuggers/performance monitoring is a portable way
3) A globally configurable interrupt priorities
mechanism...
I have nothing against providing a compatible
set_vector just to make libchip happy but
as I have already explained in other
mails (months ago), I really think that the ISR
connection should be handled by the BSP and that no
code containing irq connection should exist the
rtems generic layers... Thus I really dislike
libchip on this aspect because in a long term
it will force to adopt the less reach API
for interrupt handling that exists (set_vector).
Additional note : I think the _ISR_Is_in_progress()
inline routine should be :
1) Put in a processor specific section,
2) Should not rely on a global variable,
As :
a) on symmetric MP, there is one interrupt level
per CPU,
b) On processor that have an ISP (e,g 68040),
this variable is useless (MSR bit testing could
be used)
c) On PPC, instead of using the address of the
variable via __CPU_IRQ_info.Nest_level a dedicated
SPR could be used.
NOTE: most of this is also true for _Thread_Dispatch_disable_level
END NOTE
--------
Please do not take what I said in the mail as a criticism for
anyone who submitted ppc code. Any code present helped me
a lot understanding PPC behavior. I just wanted by this
mail to :
1) try to better understand the actual code,
2) propose concrete ways of enhancing current code
by providing an alternative implementation for MCP750. I
will make my best effort to try to brake nothing but this
is actually hard due to the file layout organisation.
3) make understandable some changes I will probably make
if joel let me do them :-)
Any comments/objections are welcomed as usual.
--
__
/ ` Eric Valette
/-- __ o _. Canon CRF
(___, / (_(_(__ Rue de la touche lambert
35517 Cesson-Sevigne Cedex
FRANCE
Tel: +33 (0)2 99 87 68 91 Fax: +33 (0)2 99 84 11 30
E-mail: valette@crf.canon.fr
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in libcpu/powerpc/mpc860/clock/clock.c:InstallClock() the reload value for
the PIT is defined as:
pit_value = (BSP_Configuration.microseconds_per_tick *
Cpu_table.clicks_per_usec) - 1 ;
What exactly is a tick, and what is a click?
My confusion stems from the fact, that Jay defines clicks_per_usec to 1
which is correct for his configuration, where a 4MHz clock is predivided
by 4 and then fed to the PIT. So I assume a "click" is just the period of
the PIT input frequency.
However, our HW config seems to have 32.768 kHz crystal input for PIT.
Mandatory division by 4 means 8.196kHz (122usec) at the PIT.
I think, the above assignment should read:
pit_value = (BSP_Configuration.microseconds_per_tick /
Cpu_table.clicks_per_usec) - 1;
where I can define Cpu_table.clicks_per_usec in bspstart.c to 122
(clicks_per_usec). That would lead to a PIT reload value of
10000/122 - 1 = 81 to reach a 10ms "tick" period.
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in libcpu/powerpc/mpc860/clock/clock.c:InstallClock() the reload value for
the PIT is defined as:
pit_value = (BSP_Configuration.microseconds_per_tick *
Cpu_table.clicks_per_usec) - 1 ;
What exactly is a tick, and what is a click?
My confusion stems from the fact, that Jay defines clicks_per_usec to 1
which is correct for his configuration, where a 4MHz clock is predivided
by 4 and then fed to the PIT. So I assume a "click" is just the period of
the PIT input frequency.
However, our HW config seems to have 32.768 kHz crystal input for PIT.
Mandatory division by 4 means 8.196kHz (122usec) at the PIT.
I think, the above assignment should read:
pit_value = (BSP_Configuration.microseconds_per_tick /
Cpu_table.clicks_per_usec) - 1;
where I can define Cpu_table.clicks_per_usec in bspstart.c to 122
(clicks_per_usec). That would lead to a PIT reload value of
10000/122 - 1 = 81 to reach a 10ms "tick" period.
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warning.
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This one is an enhancement to acpolish.
It replaces some Makefile variables by others variable in Makefile.ins
(tries to use unique name for some variables). It therefore eases
parsing Makefile.ins for further automatic Makefile.in conversions in
future.
To apply:
cd <rtems-source-tree>
sh <path-to>/rtems-rc-19990407-8.sh
./autogen
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Date: Mon, 12 Apr 1999 00:38:04 +0000
From: Brendan Simon <brendan@dgs.monash.edu.au>
To: Jay Monkman <jmonkman@frasca.com>, "joel@OARcorp.com" <joel@oarcorp.com>
Subject: [Fwd: Goof in SMC initialize for mpc860]
Nick Simon reported this bug in the eth_comm BSP sources. I see that it is
still there in the latest snapshot that Joel sent me (thanks). I thought I
better forward this on to you guys.
Brendan.
Nick.SIMON@syntegra.bt.co.uk wrote:
> Sice I believe you're using the same base BSP as I am (you sent it to me) I
> thought I'd mention..
>
> In console-generic.c, in m860_smc_initialize, the receive buffer is malloced
> and assigned to RxBd[port+3]-> buffer - it should be [port-1].
>
> TTFN
B
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In c/src/exec/score/cpu/powerpc/rtems/score/ppc.h:
A lot of hardware interrupts were omitted. Patch enclosed.
I have also added the 821.
In c/src/exec/score/cpu/powerpc/rtems/score/cpu.h:
My patch adds the 821.
In c/src/exec/score/cpu/powerpc/cpu.c:
I have added the MPC821, and also fixed up for the missing hardware
interrupts. It is also inconsistent with
c/src/lib/libcpu/powerpc/mpc860/vectors/vectors.S. This has been fixed.
In c/src/lib/libcpu/powerpc/mpc860/vectors/vectors.S:
Fixed an inconsistency with cpu.c.
I also include some new files to go with the above patches. These are the
cpu library rtems-19990331/c/src/lib/libcpu/powerpc/mpc821/* and
c/src/exec/score/cpu/powerpc/mpc821.h which are minor modifications of
the 860 equivalents.
Other comments:
The various accesses to the DPRAM on the 860 are done with a linktime
symbol. This could be done dynamically at run time by reading the immr
register, and masking off the lower 16 bits. This takes the same amount
of time as loading an address constant, and the same number of
instructions as well (2).
In c/src/lib/libcpu/powerpc/mpc860/console-generic/console-generic.c:
This will silently fail if you attempt to use SCC1. This is only relevant
if you are not using SCC1 for ethernet.
This file also sets one of port B output pins for each port. This is NOT
generic, it should be in the BSP specific console driver.
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Ian Lance Taylor <ian@airs.com> to note that condition codes
are modified.
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This is the first real automake patch.
It adds automake support to c/build-tools and cleans up a few minor
issues.
I consider this to be a testing probe to examine problems with automake.
Therefore, this patch is just a more or less harmless replacement of the
former RTEMS Makefiles and I expect it not last for long. If you want to
give automake Makefiles a public try and if you want/need to learn about
problems with it, then it's about time for a new snapshot, IMO. I may
have screwed up something not directly related to automake, but I expect
very few (none to be precise) problems with automake. However, somebody
should at least try building on Cygwin. If you feel a bit more
adventureous, then I also can continue to submit more patches.
[FYI: I still have a couple of automake files laying around, but they
need some cleanup before being submitted as patches. Now, that I am just
into it, I'll perhaps submit another one tonight :-]
After applying this patch (patch -p1 -E <
<path-to>/rtems-rc-19990318-0), first run the "autogen" script from the
toplevel source directory, before committing to CVS. Be careful about
dependencies between Makefile.am and Makefile.ins when cutting tarballs
from CVS. Makefile.ins are required to be newer than Makefile.ams,
otherwise users would need to have automake, autoconf and perl. Some
people recommend to "touch" all Makefile.in after checkout from cvs (cf.
egcs/contrib/egcs_update).
ATTENTION:
* This patch adds a number of new files.
* remove aclocal/exeext.m4 and aclocal/cygwin.m4 from CVS, They are now
covered by autoconf-2.13`s AC_EXEEXT.
Some features/side-effects which are probably interesting for you:
In a configured build-tree "cd c/build-tools", then try
* "make RTEMS_BSP=<bsp> install"
* "make RTEMS_BSP=<bsp> dist"
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This patch is the most scary of all proposals I've been mailing to you
this week until now.
It consists of 3 parts:
1. a patch
2. a perl script (acpolish)
3. a shell script wrapper to invoke the perl-script.
The perl-script reads in each Makefile.in and modifies them
("polishes/beautifies" them :-).
These modifications are not easy to describe:
Basically, it hard-codes some automake Makefile-variables and rules into
RTEMS autoconf-Makefile.ins (Note: autoconf vs. automake!!) and converts
some settings/variables to configure scripts' requirements (Yes,
plural).
E.g. it adds the automake standard variables $top_builddir and $subdir,
adds dependency rules for automatic re-generation of Makefiles from
Makefile.in, adds support variables for relative paths to multiple
configure scripts etc.
The patch is a one-line patch to enable the support of the new features
added by acpolish.
The shell script is a wrapper which pokes around inside of the source
tree for Makefile.ins and invokes acpolish on all autoconf-Makefile.ins.
acpolish is designed to be able to run several times on the same
Makefile.in and may once become a more general tool to convert RTEMS
Makefile.in to automake. Therefore, I'd like to keep it inside of source
tree. (e.g. as contrib/acpolish or c/update-tools/acpolish). However, it
doesn't make sense to export it outside of RTEMS.
To apply this:
cd <source-tree>
patch -p1 -E < <path-to-patch>/rtems-rc-19990318-1.diff
tar xzvf <path-to>/rtems-rc-polish.tar.gz
./rtems-polish.sh
./autogen
Note: The path contrib/acpolish is hard-coded into rtems-polish.sh, if
you decide to put it in an alternative place, please modify
rtems-polish.sh to reflect this change.
Later:
cvs rm make/rtems.cfg (It isn't used anymore)
cvs add contrib
cvs add contrib/acpolish
cvs commit
I've tested this intensively, but naturally I can't exclude bugs.
Ralf.
PS.: Most probably, this is the last "Towards automake" patch. The next
one probably will be a real automake patch.
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patch.
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in the eth_comm BSP documentation.
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Here is a patch which slightly improves the i386 interrupt handling
macros. These macros were written to use both input and output
parameters, which is not necessary. This patch changes them to use
only an input or output parameter, as appropriate. It also changes
the constraints to permit the interrupt level to be loaded directly in
and out of memory, rather than always requiring a register.
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earlier to CVS.
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> 5) rtems-rc-19990202-1.diff/reorg-install.sh
>
> reorg-install.sh fixes a Makefile variable name clash of RTEMS
> configuration files and automake/autoconf standards.
> Until now, RTEMS used $(INSTALL) for install-if-change. Automake and
> autoconf use $(INSTALL) for a bsd-compatible install. As
> install-if-change and bsd-install are not compatible, I renamed all
> references to install-if-changed to $(INSTALL_CHANGED) and used
> $(INSTALL) for bsd-install (==automake/autoconf standard). When
> automake will be introduced install-if-change will probably be replaced
> by $(INSTALL) and therefore will slowly vanish. For the moment, this
> patch fixes a very nasty problem which prevents adding any automake file
> until now (There are still more).
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> 4) rtems-rc-19990202-0.diff /reorg-score-cpu.sh
>
> reorg-score-cpu.sh reorganizes the cpu/<cpu>/* subdirectories in a
> similar manner than previous reorg scripts did. rtems-rc-19990202-0.diff
> contains the diffs after reorg-score-cpu.sh has been run on a
> rtems-19981215 snapshot + my patches up to rtems-rc-19990131-2.diff.
>
> This patch is rather nasty and may break something. However, I've tested
> it for about 10 different target/bsp pairs and believe to have shaken
> out most bugs.
I wonder about the following .h files that were not moved:
a29k/asm.h
a29k/cpu_asm.h
i386/asm.h
i960/asm.h
m68k/asm.h
m68k/m68302.h
m68k/m68360.h
m68k/qsm.h
m68k/sim.h
mips64orion/asm.h
mips64orion/cpu_asm.h
mips64orion/mips64orion.h
no_cpu/asm.h
no_cpu/cpu_asm.h
powerpc/asm.h
powerpc/mpc860.h
sh/asm.h
sparc/asm.h
sparc/erc32.h
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You will find enclosed a patch which contains, for Intel PC386 target :
- an Ethernet driver for DEC21140 device based boards.
- a simple cache management with paging mechanism.
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based board.
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> > I think I have found a bug in src/exec/scor/sparc/cpu/erc32.h in:
> >
> > #define ERC32_Disable_interrupt( _source, _previous ) \
> > do { \
> > unsigned32 _level; \
> > unsigned32 _mask = 1 << (_source); \
> > \
> > sparc_disable_interrupts( _level ); \
> > (_previous) = ERC32_MEC.Interrupt_Mask; \
> > ERC32_MEC.Interrupt_Mask = _previous | _mask; \
> > sparc_enable_interrupts( _level ); \
> > (_previous) &= ~_mask; \ <- IS THIS CORRECT...?
> > } while (0)
> >
> > The previous interrupt mask is returned after first clearing the
> > bit to be disabled, regardless whether the bit was set before or
> > not. If the bit was set (interrupt masked), subsequent call to
> > ERC32_Restore_interrupt() will enable the interrupt even though
> > it was supposed to be masked. This is indeed what happens in
> > DEBUG_puts when polled console I/O is used. In my opinion, the
> > last statement in the macro should be removed - what is your opinion?
>
> I think the "~" shouldn't be there. I recall that the intent of that line
> is to only return the state of the interrupts you were concerned with.
> Removing the line returns entire state. Given that the value returned
> shuold only be used in conjunction with the map, I suppose either removing
> the ~ or the entire line is correct? I can go either way. Just let me
> know which you think is more correct and the source will change. :)
Hmmm, just removing the '~' should be OK. DEBUG_puts() seems to be the
only user of ERC32_Restore_interrupt() anyway ...
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.s files to .S in conformance with GNU conventions. This is a
minor step along the way to supporting automake.
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cosmetic things.
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Finally I am through: I have found the last bugs that made RTEMS-
4.0-beta3 start on my ppc403 board from ROM. So now the '403
support is up to date again.
Roughly I have added the following features:
- support for the on-chip interrupt controller (in a separate module)
- interrupt support for the console device
- termios support for the console device
==============================================
Since the BSP behaivour changed in some details (console no
longer is polling, other memory layout etc) I have created a new
BSP "helas403" rather than changing the "papyrus" BSP. The old
"polled" console driver still sticks around in "console.c.polled"
To get the BSP up and running, I had to create the new BSP files
(derived from papyrus). Besides that, the following source areas
have been changed:
- c/src/lib/libcpu/powerpc/ppc403: changes to console driver, small
changes to clock driver, new "ictrl" interrupt controller driver
- c/src/exec/score/cpu/powerpc/ppc.h: some small changes
(added ppc403 characteristics like a exception vector prefix
register, some special register definitions). I am quite sure, they
are compatible with the existing sources, although I did not check
- c/src/exec/score/cpu/powerpc/cpu.c: There is one severe
limitation in the exception entries: Due to the current code
arrangement, the "branch absolute" to the ISR handler may only
jump to the first 128MByte or the last 128MByte of the 4GByte
address range. When the ppc403 is running out of ROM, the ROM
functions are located in the last 128MByte (0xFFF00000 and up).
These addresses were not handled correctly (sign reduced) in
"install_raw_handler". The change I added should work on existing
ppc BSPs aswell...
- c/src/lib/libc/termios.c: During my tests, I added one change you
sent me, so this patch will already be incorporated in the current
source tree.
There are some smaller changes, see the attached diff file.
=========================================
Concerning the GNU toolchain:
I tried several tool chains. Finally I almost succeeded with
egcs-1.0.3a with patch egcs-1.0.3-rtems-diff-19980527
I had to add the following lines to the egcs files. Without them
configure complaint that the cross compiler could not generate
executable output.
- additional lines needed in egcs distribution in file
gcc/config/rs6000/rtems.h:
+++ lines start
#undef STARTFILE_DEFAULT_SPEC
#define STARTFILE_DEFAULT_SPEC "ecrti.o%s"
#undef ENDFILE_DEFAULT_SPEC
#define ENDFILE_DEFAULT_SPEC "ecrtn.o%s"
++++ lines end
As far as I have seen in the Changelog of egcs, you have recently
sent two patches affecting the powerpc support, but they were
added in the wrong order.... :-(
egcs-19980628 with patch egcs-19980628-rtems-diff-19980707 does
not work!
I used binutils 2.9.1 with patch binutils-2.9.1-rtems-diff-19980515
(binutils 2.8.1 does not work, internal error in gas)
and newlib-1.8.0 with patch newlib-1.8.0-rtems-diff-19980707
Finally I had to poke a line in the "bit" script, since, on my LINUX
machine, the GNU make is only available as "make", not as
"gmake"...
For all the tools and newlib I selected configuration "powerpc-
rtems".
--------------------------------------------
IMD Ingenieurbuero fuer Microcomputertechnik
Thomas Doerfler Herbststrasse 8
D-82178 Puchheim Germany
email: td@imd.m.isar.de
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Please find enclosed a patch which enables me to build the bare-bsp for
sh-rtems.
Changes:
1. Add preinstall to libbsp/bare/include/Makefile.in
2. Removed FORCEIT, add preinstall to
libbsp/sh/gensh1/include/Makefile.in
3. Disabled support of set_vector from sh code (shared/setvec.c is still
present but isn't used anymore), set_vector replaced with standard rtems
functions.
Problems still present:
1. Support of spin-delays in bare bsp
2. Proper support of cpu frequency
To configure I used:
<srcdir>/configure \
--target=sh-rtems \
--prefix=<instdir>/sh-bare \
--enable-bare-cpu-model=sh7032 \
--enable-bare-cpu-cflags='-Wall -m1 -DMHZ=20
-DCPU_CONSOLE_DEVNAME="\"/dev/null\""'
--enable-rtemsbsp=bare \
--disable-networking \
--disable-cxx \
--disable-posix \
--disable-tests
IMO, if there are no objections to this patch, a similar approach should
be applied to all CPUs/BSPs (esp. hppa1.1, mips64orion, ppc403, because
they apply set_vector inside of libcpu).
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1. Finally fixes raw interrupts for pc386
2. Makes some minor cleanup in console and startup
3. Makes rtems_termios_dequeue_characters() to return count of
outstanding chars - it allows to simplify console isrs a little
bit.
4. pc386 uart modified to be friendlier to termios parameter changes,
to have minor performance improvement and to take advantage of
of above termios modification.
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patches missing from 980911.
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Here is a patch that enables to catch exception
and get message before crashing RTEMS :)
It should be generic to any Intel port although enabled
only for pc386 BSP...
[Joel] I fixed the bug I introduced in irq_asm.s...
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inline with the new IRQ structure.
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Enabled on the pc386.
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Here is a enhanced version of my previous patch. This patch enables
to potentially share the new interrupt management code for all Intel targets
(pc386, go32 and force386) bsp.
Note : this patch is complete only for pc386. It still needs to
be completed for go32 and force386. I carrefully checked
that anything needed is in for force386 (only some function
name changes for IDT manipulation and GDT segment
manipulation). But anyway I will not be able to test any
of theses targets...
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important distinctions between CPU models which are not made by gcc.
These distinctions help give us a more optimized memcpy(). This is important
for message queues and KA9Q.
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use a wildcard rule instead of explicit listing all include files
(I have more libcpu header files than the public version has. This patch
removes the need to patch this Makefile for my private bsps)
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the CPU family name constants.
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