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score: Work area initialization API change

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The work areas (RTEMS work space and C program heap) will be initialized
now in a separate step and are no longer part of
rtems_initialize_data_structures().  Initialization is performed with
tables of Heap_Area entries.  This allows usage of scattered memory
areas present on various small scale micro-controllers.

The sbrk() support API changes also.  The bsp_sbrk_init() must now deal
with a minimum size for the first memory chunk to take the configured
work space size into account.
This commit is contained in:
Sebastian Huber
2012-08-09 16:48:00 +02:00
parent e4278f2050
commit 47a3cd8f73
51 changed files with 545 additions and 906 deletions
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58
doc/bsp_howto/init.t
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@@ -147,34 +147,29 @@ The @code{boot_card()} routine performs the following functions:
@item It disables processor interrupts.
@item It sets the global program name and command line argument variables
@item It sets the command line argument variables
for later use by the application.
@item If the macro is BSP_BOOTCARD_HANDLES_RAM_ALLOCATION is defined, it
will invoke the BSP specific @code{bsp_get_work_area} function to obtain
information on the amount and location of BSP RAM that is available to
be allocated to the C Program Heap and RTEMS Workspace. If the amount
of memory available for the RTEMS Workspace is less than that required
by the application (e.g. @code{rtems_configuration_get_work_space_size()},
then a message is printed using @code{printk}, @code{bsp_cleanup} is
invoked, and -1 is return to the assembly language start code. BSPs which
use this memory allocation functionality in @code{bootcard.c}
must invoke the RTEMS specific autoconf macro
@code{RTEMS_BSP_BOOTCARD_HANDLES_RAM_ALLOCATION} in the BSP's
@code{configure.ac} file.
@item It invokes the BSP specific routine @code{bsp_start()} which is
written in C and thus able to perform more advanced initialization.
Often MMU and bus initialization occurs here.
@item It invokes the BSP specific routine @code{bsp_work_area_initialize()}
which is supposed to initialize the RTEMS Workspace and the C Program Heap.
Usually the default implementation in
@code{c/src/lib/libbsp/shared/bspgetworkarea.c} should be sufficient. Custom
implementations can use @code{bsp_work_area_initialize_default()} or
@code{bsp_work_area_initialize_with_table()} available as inline functions from
@code{#include <bsp/bootcard.h>}.
@item It invokes the RTEMS directive
@code{rtems_initialize_data_structures()} to initialize the RTEMS
executive to a state where objects can be created but tasking is not
enabled.
@item If the macro is BSP_BOOTCARD_HANDLES_RAM_ALLOCATION is defined,
it will calculate the memory available for the C Program Heap and invoke
the initialization routine for the C Library with this information.
@item It invokes the BSP specific routine @code{bsp_libc_init()} to initialize
the C Library. Usually the default implementation in
@code{c/src/lib/libbsp/shared/bsplibc.c} should be sufficient.
@item It invokes the BSP specific routine @code{bsp_pretasking_hook}. On
most BSPs which utilize the framework, this routine does nothing.
@@ -188,9 +183,7 @@ thread in a multiprocessor configuration and execute API specific
extensions.
@item It invokes the BSP specific routine @code{bsp_predriver_hook}. For
most BSPs, the implementation of this routine does nothing. However,
on some BSPs, required subsystems which utilize the C Library
(e.g. @code{malloc} in particular) may be initialized at this point.
most BSPs, the implementation of this routine does nothing.
@item It invokes the RTEMS directive
@code{rtems_initialize_device_drivers()} to initialize the statically
@@ -255,28 +248,13 @@ routine.
@subsection RTEMS Pretasking Callback
The method @code{bsp_pretasking_hook()} is the BSP specific routine
invoked once RTEMS API initialization is complete but before interrupts
and tasking are enabled. No tasks -- not even the IDLE task -- have
been created when this hook is invoked. The pretasking hook is optional
The method @code{bsp_pretasking_hook()} is the BSP specific routine invoked
once RTEMS API initialization is complete but before interrupts and tasking are
enabled. The idle thread exists at this time. The pretasking hook is optional
and the user may use the shared version.
The @code{bsp_pretasking_hook()} routine is the appropriate place to
initialize any support components which depend on the RTEMS APIs.
Older BSPs that do not take full advantage of @code{boot_card()}
may initialize the RTEMS C Library in their implementation of
@code{bsp_pretasking_hook()}. This initialization includes the
application heap used by the @code{malloc} family of routines as well
as the reentrancy support for the C Library.
The routine @code{bsp_libc_init} routine invoked from the
either @code{boot_card()} or (less preferable) the BSP specific
@code{bsp_pretasking_hook()} routine is passed the starting address,
length, and growth amount passed to @code{sbrk}. This "sbrk amount"
is only used if the heap runs out of memory. In this case, the RTEMS
malloc implementation will invoked @code{sbrk} to obtain more memory.
See @ref{Miscellaneous Support Files sbrk() Implementation} for more
details.
The @code{bsp_pretasking_hook()} routine is the appropriate place to initialize
any BSP specific support components which depend on the RTEMS APIs.
@subsection RTEMS Predriver Callback