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authorJoel Sherrill <joel.sherrill@OARcorp.com>2008-06-02 16:07:42 +0000
committerJoel Sherrill <joel.sherrill@OARcorp.com>2008-06-02 16:07:42 +0000
commita73e356164c942fb08172cf4636f9956c3acc276 (patch)
treecf211d176fee9612a0b8e4f11e02a72ffb7dbf1a /doc
parent2008-06-01 Ralf Corsépius <ralf.corsepius@rtems.org> (diff)
downloadrtems-a73e356164c942fb08172cf4636f9956c3acc276.tar.bz2
2008-06-02 Joel Sherrill <joel.sherrill@oarcorp.com>
* user/bsp.t, user/init.t: Rework initialization and BSP chapters to account for changes to initialization framework.
Diffstat (limited to 'doc')
-rw-r--r--doc/ChangeLog5
-rw-r--r--doc/user/bsp.t164
-rw-r--r--doc/user/init.t288
3 files changed, 273 insertions, 184 deletions
diff --git a/doc/ChangeLog b/doc/ChangeLog
index 8a44923278..931c932b11 100644
--- a/doc/ChangeLog
+++ b/doc/ChangeLog
@@ -1,3 +1,8 @@
+2008-06-02 Joel Sherrill <joel.sherrill@oarcorp.com>
+
+ * user/bsp.t, user/init.t: Rework initialization and BSP chapters to
+ account for changes to initialization framework.
+
2008-05-22 Joel Sherrill <joel.sherrill@OARcorp.com>
* user/conf.t: Add baseline interface for Watchdog Driver.
diff --git a/doc/user/bsp.t b/doc/user/bsp.t
index 01c0075d79..50ff42ee11 100644
--- a/doc/user/bsp.t
+++ b/doc/user/bsp.t
@@ -33,20 +33,9 @@ initialization code are highly processor and target dependent,
the logical functionality of these actions are similar across a
variety of processors and target platforms.
-Normally, the application's initialization is
-performed at two separate times: before the call to
-@code{@value{DIRPREFIX}initialize_executive}
-(reset application initialization) and
-after @code{@value{DIRPREFIX}initialize_executive}
-in the user's initialization tasks
-(local and global application initialization). The order of the
-startup procedure is as follows:
-
-@enumerate
-@item Reset application initialization.
-@item Call to @code{@value{DIRPREFIX}initialize_executive}
-@item Local and global application initialization.
-@end enumerate
+Normally, the BSP and some of the application initialization is
+intertwined in the RTEMS initialization sequence controlled by
+the shared function @code{boot_card()}.
The reset application initialization code is executed
first when the processor is reset. All of the hardware must be
@@ -57,49 +46,45 @@ application. Some of the hardware components may be initialized
in this code as well as any application initialization that does
not involve calls to RTEMS directives.
-The processor's Interrupt Vector Table which will be
-used by the application may need to be set to the required value
-by the reset application initialization code. Because
-interrupts are enabled automatically by RTEMS as part of the
-@code{@value{DIRPREFIX}initialize_executive} directive,
-the Interrupt Vector Table MUST
-be set before this directive is invoked to ensure correct
-interrupt vectoring. The processor's Interrupt Vector Table
-must be accessible by RTEMS as it will be modified by the
-@code{@value{DIRPREFIX}interrupt_catch} directive.
-On some CPUs, RTEMS installs it's
-own Interrupt Vector Table as part of initialization and thus
-these requirements are met automatically. The reset code which
-is executed before the call to @code{@value{DIRPREFIX}initialize_executive}
-has the following requirements:
+The processor's Interrupt Vector Table which will be used by the
+application may need to be set to the required value by the reset
+application initialization code. Because interrupts are enabled
+automatically by RTEMS as part of the context switch to the first task,
+the Interrupt Vector Table MUST be set before this directive is invoked
+to ensure correct interrupt vectoring. The processor's Interrupt Vector
+Table must be accessible by RTEMS as it will be modified by the when
+installing user Interrupt Service Routines (ISRs) On some CPUs, RTEMS
+installs it's own Interrupt Vector Table as part of initialization and
+thus these requirements are met automatically. The reset code which is
+executed before the call to any RTEMS initialization routines has the
+following requirements:
@itemize @bullet
-@item Must not make any RTEMS directive calls.
+@item Must not make any blocking RTEMS directive calls.
-@item If the processor supports multiple privilege levels,
-must leave the processor in the most privileged, or supervisory,
-state.
+@item If the processor supports multiple privilege levels, must leave
+the processor in the most privileged, or supervisory, state.
@item Must allocate a stack of at least @code{@value{RPREFIX}MINIMUM_STACK_SIZE}
-bytes and initialize the stack pointer for the
-@code{@value{DIRPREFIX}initialize_executive} directive.
+bytes and initialize the stack pointer for the initialization process.
@item Must initialize the processor's Interrupt Vector Table.
@item Must disable all maskable interrupts.
-@item If the processor supports a separate interrupt stack,
-must allocate the interrupt stack and initialize the interrupt
-stack pointer.
+@item If the processor supports a separate interrupt stack, must allocate
+the interrupt stack and initialize the interrupt stack pointer.
+
@end itemize
-The @code{@value{DIRPREFIX}initialize_executive} directive does not return to
-the initialization code, but causes the highest priority
-initialization task to begin execution. Initialization tasks
-are used to perform both local and global application
-initialization which is dependent on RTEMS facilities. The user
-initialization task facility is typically used to create the
-application's set of tasks.
+At the end of the initialization sequence, RTEMS does not return to the
+BSP initialization code, but instead context switches to the highest
+priority task to begin application execution. This task is typically
+a User Initialization Task which is responsible for performing both
+local and global application initialization which is dependent on RTEMS
+facilities. It is also responsible for initializing any higher level
+RTEMS services the application uses such as networking and blocking
+device drivers.
@subsection Interrupt Stack Requirements
@@ -121,38 +106,36 @@ stack usage must account for the following requirements:
@item Application subroutine calls
@end itemize
-The size of the interrupt stack must be greater than
-or equal to the constant @code{@value{RPREFIX}MINIMUM_STACK_SIZE}.
+The size of the interrupt stack must be greater than or equal to the
+constant @code{@value{RPREFIX}MINIMUM_STACK_SIZE}.
@subsection Processors with a Separate Interrupt Stack
-Some processors support a separate stack for
-interrupts. When an interrupt is vectored and the interrupt is
-not nested, the processor will automatically switch from the
-current stack to the interrupt stack. The size of this stack is
-based solely on the worst-case stack usage by interrupt service
-routines.
-
-The dedicated interrupt stack for the entire
-application is supplied and initialized by the reset and
-initialization code of the user's board support package. Since
-all ISRs use this stack, the stack size must take into account
-the worst case stack usage by any combination of nested ISRs.
-
-@subsection Processors without a Separate Interrupt Stack
-
-Some processors do not support a separate stack for
-interrupts. In this case, without special assistance every
-task's stack must include enough space to handle the task's
-worst-case stack usage as well as the worst-case interrupt stack
-usage. This is necessary because the worst-case interrupt
-nesting could occur while any task is executing.
-
-On many processors without dedicated hardware managed
-interrupt stacks, RTEMS manages a dedicated interrupt stack in
-software. If this capability is supported on a CPU, then it is
-logically equivalent to the processor supporting a separate
-interrupt stack in hardware.
+Some processors support a separate stack for interrupts. When an
+interrupt is vectored and the interrupt is not nested, the processor
+will automatically switch from the current stack to the interrupt stack.
+The size of this stack is based solely on the worst-case stack usage by
+interrupt service routines.
+
+The dedicated interrupt stack for the entire application on some
+architectures is supplied and initialized by the reset and initialization
+code of the user's Board Support Package. Whether allocated and
+initialized by the BSP or RTEMS, since all ISRs use this stack, the
+stack size must take into account the worst case stack usage by any
+combination of nested ISRs.
+
+@subsection Processors Without a Separate Interrupt Stack
+
+Some processors do not support a separate stack for interrupts. In this
+case, without special assistance every task's stack must include
+enough space to handle the task's worst-case stack usage as well as
+the worst-case interrupt stack usage. This is necessary because the
+worst-case interrupt nesting could occur while any task is executing.
+
+On many processors without dedicated hardware managed interrupt stacks,
+RTEMS manages a dedicated interrupt stack in software. If this capability
+is supported on a CPU, then it is logically equivalent to the processor
+supporting a separate interrupt stack in hardware.
@section Device Drivers
@@ -178,23 +161,20 @@ the application is to utilize timeslicing, the clock manager, the
timer manager, the rate monotonic manager, or the timeout option on blocking
directives.
-The clock tick is usually provided as an interrupt
-from a counter/timer or a real-time clock device. When a
-counter/timer is used to provide the clock tick, the device is
-typically programmed to operate in continuous mode. This mode
-selection causes the device to automatically reload the initial
-count and continue the countdown without programmer
-intervention. This reduces the overhead required to manipulate
-the counter/timer in the clock tick ISR and increases the
-accuracy of tick occurrences. The initial count can be based on
-the microseconds_per_tick field in the RTEMS Configuration
-Table. An alternate approach is to set the initial count for a
-fixed time period (such as one millisecond) and have the ISR
-invoke @code{@value{DIRPREFIX}clock_tick}
-on the microseconds_per_tick boundaries.
-Obviously, this can induce some error if the configured
-microseconds_per_tick is not evenly divisible by the chosen
-clock interrupt quantum.
+The clock tick is usually provided as an interrupt from a counter/timer
+or a real-time clock device. When a counter/timer is used to provide the
+clock tick, the device is typically programmed to operate in continuous
+mode. This mode selection causes the device to automatically reload the
+initial count and continue the countdown without programmer intervention.
+This reduces the overhead required to manipulate the counter/timer in
+the clock tick ISR and increases the accuracy of tick occurrences.
+The initial count can be based on the microseconds_per_tick field
+in the RTEMS Configuration Table. An alternate approach is to set
+the initial count for a fixed time period (such as one millisecond)
+and have the ISR invoke @code{@value{DIRPREFIX}clock_tick} on the
+configured @code{microseconds_per_tick} boundaries. Obviously, this
+can induce some error if the configured @code{microseconds_per_tick}
+is not evenly divisible by the chosen clock interrupt quantum.
It is important to note that the interval between
clock ticks directly impacts the granularity of RTEMS timing
@@ -235,7 +215,7 @@ switch extension would save and restore the context of the
device.
For more information on user extensions, refer to the
-User Extensions chapter.
+@ref{User Extensions Manager} chapter.
@section Multiprocessor Communications Interface (MPCI)
diff --git a/doc/user/init.t b/doc/user/init.t
index 3dc368f9d1..6bfb1fffe8 100644
--- a/doc/user/init.t
+++ b/doc/user/init.t
@@ -10,17 +10,19 @@
@section Introduction
-The initialization manager is responsible for
+The Initialization Manager is responsible for
initiating and shutting down RTEMS. Initiating RTEMS involves
creating and starting all configured initialization tasks, and
for invoking the initialization routine for each user-supplied
device driver. In a multiprocessor configuration, this manager
also initializes the interprocessor communications layer. The
-directives provided by the initialization manager are:
+directives provided by the Initialization Manager are:
@itemize @bullet
-@item @code{@value{DIRPREFIX}initialize_executive_early} - Initialize RTEMS and do NOT Start Multitasking
-@item @code{@value{DIRPREFIX}initialize_executive_late} - Complete Initialization and Start Multitasking
+@item @code{@value{DIRPREFIX}initialize_data_structures} - Initialize RTEMS Data Structures
+@item @code{@value{DIRPREFIX}initialize_before_drivers} - Perform Initialization Before Device Drivers
+@item @code{@value{DIRPREFIX}initialize_device_drivers} - Initialize Device Drivers
+@item @code{@value{DIRPREFIX}initialize_start_multitasking} - Complete Initialization and Start Multitasking
@item @code{@value{DIRPREFIX}shutdown_executive} - Shutdown RTEMS
@end itemize
@@ -53,41 +55,40 @@ This transformation typically involves changing priority and
execution mode. RTEMS does not automatically delete the
initialization tasks.
-@subsection The System Initialization Task
+@subsection System Initialization
-The System Initialization Task is responsible for
-initializing all device drivers. As a result, this task has a
-higher priority than all other tasks to ensure that no
-application tasks executes until all device drivers are
-initialized. After device initialization in a single processor
-system, this task will delete itself.
+System Initialization begins with board reset and continues
+through RTEMS initialization, initialization of all device
+drivers, and eventually a context switch to the first user
+task. Remember, that interrupts are disabled during
+initialization and the @i{initialization thread} is not
+a task in any sense and the user should be very careful
+during initialzation.
-The System Initialization Task must have enough stack
-space to successfully execute the initialization routines for
+The BSP must ensure that the there is enough stack
+space reserved for the initialization "thread" to
+successfully execute the initialization routines for
all device drivers and, in multiprocessor configurations, the
Multiprocessor Communications Interface Layer initialization
-routine. The CPU Configuration Table contains a field which
-allows the application or BSP to increase the default amount of
-stack space allocated for this task.
-
-In multiprocessor configurations, the System
-Initialization Task does not delete itself after initializing
-the device drivers. Instead it transforms itself into the
-Multiprocessing Server which initializes the Multiprocessor
-Communications Interface Layer, verifies multiprocessor system
-consistency, and processes all requests from remote nodes.
+routine.
@subsection The Idle Task
The Idle Task is the lowest priority task in a system
and executes only when no other task is ready to execute. This
-task consists of an infinite loop and will be preempted when any
-other task is made ready to execute.
+default implementation of this task consists of an infinite
+loop. RTEMS allows the Idle Task body to be replaced by a CPU
+specific implementation, a BSP specific implementation or an
+application specific implementation.
+
+The Idle Task is preemptible and @b{WILL} be preempted when
+any other task is made ready to execute. This characteristic is
+critical to the overall behavior of any application.
@subsection Initialization Manager Failure
-The @code{@value{DIRPREFIX}ifatal_error_occurred} directive will be called
-from @code{@value{DIRPREFIX}initialize_executive}
+The @code{@value{DIRPREFIX}fatal_error_occurred} directive will
+be invoked from @code{@value{DIRPREFIX}initialize_executive}
for any of the following reasons:
@itemize @bullet
@@ -118,42 +119,72 @@ initialization sequence.
@item If any of the user initialization tasks cannot be
created or started successfully.
@end itemize
+
+A discussion of RTEMS actions when a fatal error occurs
+may be found @ref{Fatal Error Manager Announcing a Fatal Error}.
+
@section Operations
@subsection Initializing RTEMS
-The Initializatiton Manager directives are called by the
-board support package framework as part of its initialization
-sequence. RTEMS assumes that the board support package
+The Initialization Manager directives are called by the
+Board Support Package framework as part of its initialization
+sequence. RTEMS assumes that the Board Support Package
successfully completed its initialization activities. These
directives initialize RTEMS by performing the following actions:
@itemize @bullet
@item Initializing internal RTEMS variables;
@item Allocating system resources;
-@item Creating and starting the System Initialization Task;
@item Creating and starting the Idle Task;
+@item Initialize all device drivers;
@item Creating and starting the user initialization task(s); and
@item Initiating multitasking.
@end itemize
-This directive MUST be called before any other RTEMS
-directives. The effect of calling any RTEMS directives before
-@code{@value{DIRPREFIX}initialize_executive_early}
-is unpredictable. Many of RTEMS actions
-during initialization are based upon the contents of the
-Configuration Table. For more information regarding the format
-and contents of this table, please refer to the chapter
-Configuring a System.
+The initialization directives MUST be called in the proper
+sequence before any blocking directives may be used. The services
+in this manager should be invoked just once per application
+and in precisely the following order:
+
+@itemize @bullet
+@item @code{@value{DIRPREFIX}initialize_data_structures}
+@item @code{@value{DIRPREFIX}initialize_before_drivers}
+@item @code{@value{DIRPREFIX}initialize_device_drivers}
+@item @code{@value{DIRPREFIX}initialize_start_multitasking}
+@end itemize
+
+It is recommended that the Board Support Package use the
+provided framework which will invoke these services as
+part of the executing the function @code{boot_card} in the
+file @code{c/src/lib/libbsp/shared/bootcard.c}. This
+framework will also assist in allocating memory to the
+RTEMS Workspace and C Program Heap and initializing the
+C Library.
+
+The effect of calling any blocking RTEMS directives before
+@code{@value{DIRPREFIX}initialize_start_multitasking}
+is unpredictable but guaranteed to be bad. Afer the
+directive @code{@value{DIRPREFIX}initialize_data_structures}
+is invoked, it is permissible to allocate RTEMS objects and
+perform non-blocking operations. But the user should be
+distinctly aware that multitasking is not available yet
+and they are @b{NOT} executing in a task context.
+
+Many of RTEMS actions during initialization are based upon
+the contents of the Configuration Table. For more information
+regarding the format and contents of this table, please refer
+to the chapter @ref{Configuring a System}.
The final step in the initialization sequence is the
initiation of multitasking. When the scheduler and dispatcher
are enabled, the highest priority, ready task will be dispatched
-to run. Control will not be returned to the board support
-package after multitasking is enabled until
-@code{@value{DIRPREFIX}shutdown_executive_late}
-the directive is called.
+to run. Control will not be returned to the Board Support
+Package after multitasking is enabled until the
+@code{@value{DIRPREFIX}shutdown_executive} directive is called.
+This directive is called as a side-effect of POSIX calls
+including @code{exit}.
@subsection Shutting Down RTEMS
@@ -161,26 +192,26 @@ The @code{@value{DIRPREFIX}shutdown_executive} directive is invoked by the
application to end multitasking and return control to the board
support package. The board support package resumes execution at
the code immediately following the invocation of the
-@code{@value{DIRPREFIX}initialize_executive} directive.
+@code{@value{DIRPREFIX}initialize_start_multitasking} directive.
@section Directives
-This section details the initialization manager's
+This section details the Initialization Manager's
directives. A subsection is dedicated to each of this manager's
directives and describes the calling sequence, related
constants, usage, and status codes.
@page
-@subsection INITIALIZE_EXECUTIVE_EARLY - Initialize RTEMS and do NOT Start Multitasking
+@subsection INITIALIZE_DATA_STRUCTURES - Initialize RTEMS Data Structures
-@cindex initialize RTEMS
+@cindex initialize RTEMS data structures
@subheading CALLING SEQUENCE:
@ifset is-C
-@findex rtems_initialize_executive_early
+@findex rtems_initialize_data_structures
@example
-rtems_interrupt_level rtems_initialize_executive_early(
+void rtems_initialize_data_structures(
rtems_configuration_table *configuration_table
);
@end example
@@ -198,30 +229,119 @@ NONE
@subheading DESCRIPTION:
-This directive is called when the board support
-package has completed its initialization to allow RTEMS to
-initialize the application environment based upon the
-information in the Configuration Table, CPU Dependent
-Information Table, User Initialization Tasks Table, Device
-Driver Table, User Extension Table, Multiprocessor Configuration
-Table, and the Multiprocessor Communications Interface (MPCI)
-Table. This directive returns to the caller after completing
-the basic RTEMS initialization but before multitasking is
-initiated. The interrupt level in place when the directive is
-invoked is returned to the caller. This interrupt level should
-be the same one passed to
-@code{@value{DIRPREFIX}initialize_executive_late}.
+This directive is called when the Board Support
+Package has completed its basic initialization and
+allows RTEMS to initialize the application environment based upon the
+information in the Configuration Table, User Initialization
+Tasks Table, Device Driver Table, User Extension Table,
+Multiprocessor Configuration Table, and the Multiprocessor
+Communications Interface (MPCI) Table. This directive returns
+to the caller after completing the basic RTEMS initialization.
+
+@subheading NOTES:
+
+The Initialization Manager directives must be used in the
+proper sequence and invokved only once in the life of an application.
+
+This directive must be invoked with interrupts disabled.
+Interrupts should be disabled as early as possible in
+the initialization sequence and remain disabled until
+the first context switch.
+
+@page
+@subsection INITIALIZE_BEFORE_DRIVERS - Perform Initialization Before Device Drivers
+
+@cindex initialize RTEMS before device drivers
+
+@subheading CALLING SEQUENCE:
+
+@ifset is-C
+@findex rtems_initialize_before_drivers
+@example
+void rtems_initialize_before_drivers(void);
+@end example
+@end ifset
+
+@ifset is-Ada
+@example
+NOT SUPPORTED FROM Ada BINDING
+@end example
+@end ifset
+
+@subheading DIRECTIVE STATUS CODES:
+
+NONE
+
+@subheading DESCRIPTION:
+
+This directive is called by the Board Support Package as the
+second step in initializing RTEMS. This directive performs
+initialization that must occur between basis RTEMS data structure
+initialization and device driver initialization. In particular,
+in a multiprocessor configuration, this directive will create the
+MPCI Server Task. This directive returns to the caller after
+completing the basic RTEMS initialization.
@subheading NOTES:
-The application must use only one of the two
-initialization sequences:
-@code{@value{DIRPREFIX}initialize_executive} or
-@code{@value{DIRPREFIX}initialize_executive_early} and
-@code{@value{DIRPREFIX}initialize_executive_late}.
+The Initialization Manager directives must be used in the
+proper sequence and invokved only once in the life of an application.
+
+This directive must be invoked with interrupts disabled.
+Interrupts should be disabled as early as possible in
+the initialization sequence and remain disabled until
+the first context switch.
@page
-@subsection INITIALIZE_EXECUTIVE_LATE - Complete Initialization and Start Multitasking
+@subsection INITIALIZE_DEVICE_DRIVERS - Initialize Device Drivers
+
+@cindex initialize device drivers
+
+@subheading CALLING SEQUENCE:
+
+@ifset is-C
+@findex rtems_initialize_device_drivers
+@example
+void rtems_initialize_device_drivers(void);
+@end example
+@end ifset
+
+@ifset is-Ada
+@example
+NOT SUPPORTED FROM Ada BINDING
+@end example
+@end ifset
+
+@subheading DIRECTIVE STATUS CODES:
+
+NONE
+
+@subheading DESCRIPTION:
+
+This directive is called by the Board Support Package as the
+third step in initializing RTEMS. This directive initializes
+all statically configured device drivers and performs all RTEMS
+initialization which requires device drivers to be initialized.
+
+In a multiprocessor configuration, this service will initialize
+the Multiprocessor Communications Interface (MPCI) and synchronize
+with the other nodes in the system.
+
+After this directive is executed, control will be returned to
+the Board Support Package framework.
+
+@subheading NOTES:
+
+The Initialization Manager directives must be used in the
+proper sequence and invokved only once in the life of an application.
+
+This directive must be invoked with interrupts disabled.
+Interrupts should be disabled as early as possible in
+the initialization sequence and remain disabled until
+the first context switch.
+
+@page
+@subsection INITIALIZE_START_MULTITASKING - Complete Initialization and Start Multitasking
@cindex initialize RTEMS
@cindex start multitasking
@@ -229,11 +349,9 @@ initialization sequences:
@subheading CALLING SEQUENCE:
@ifset is-C
-@findex rtems_initialize_executive_late
+@findex rtems_initialize_start_multitasking
@example
-void rtems_initialize_executive_late(
- rtems_interrupt_level bsp_level
-);
+void rtems_initialize_start_multitasking(void);
@end example
@end ifset
@@ -249,21 +367,15 @@ NONE
@subheading DESCRIPTION:
-This directive is called after the
-@code{@value{DIRPREFIX}initialize_executive_early}
-directive has been called to complete
-the RTEMS initialization sequence and initiate multitasking.
-The interrupt level returned by the
-@code{@value{DIRPREFIX}initialize_executive_early}
-directive should be in bsp_level and this value is restored as
-part of this directive returning to the caller after the
-@code{@value{DIRPREFIX}shutdown_executive}
-directive is invoked.
+This directive is called after the other Initialization Manager
+directives have successfully completed. This directive
+initiates multitasking and performs a context switch to
+the first user application task and enables interrupts as
+a side-effect of that context switch.
@subheading NOTES:
-This directive MUST be the second RTEMS directive
-called and it DOES NOT RETURN to the caller until the
+This directive @b{DOES NOT RETURN} to the caller until the
@code{@value{DIRPREFIX}shutdown_executive} is invoked.
This directive causes all nodes in the system to
@@ -271,14 +383,6 @@ verify that certain configuration parameters are the same as
those of the local node. If an inconsistency is detected, then
a fatal error is generated.
-The application must use only one of the two
-initialization sequences:
-@code{@value{DIRPREFIX}initialize_executive} or
-@code{@value{DIRPREFIX}initialize_executive_early} and
-@code{@value{DIRPREFIX}initialize_executive_late}.
-
-
-
@page
@subsection SHUTDOWN_EXECUTIVE - Shutdown RTEMS