sparc stack and heap
Aleix Conchillo Flaqué
aconchillo at ieec.fcr.es
Tue Jul 25 12:31:35 UTC 2006
On 25 Jul 2006, at 14:06, Joel Sherrill wrote:
> STACK_SIZE in linkcmds looks the size of the initial stack used for
> system initialization in that BSP.
> Do you see symbols near it in start.S used to set the stack pointer?
STACK_SIZE is defined inside bspstart.c:
#define STACK_SIZE 16 + 1024
Then heap_size is calculated (in bsp_pretasking_hook) as:
heap_size = BSP_Configuration.work_space_start - (void *)&end -
heap_size &= 0xfffffff0;
bsp_libc_init ((void *) heap_start, heap_size, 0);
> The application usually uses confdefs.h to specify the RTEMS
> resources needed. confdefs.h calculates
> the required amount of workspace. If you configure 10 tasks, then
> it calculates you need 40K for corresponding
> task stacks. This is from the ticker sample:
> #define CONFIGURE_APPLICATION_NEEDS_CONSOLE_DRIVER
> #define CONFIGURE_APPLICATION_NEEDS_CLOCK_DRIVER
> #define CONFIGURE_MAXIMUM_TASKS 4
> #define CONFIGURE_RTEMS_INIT_TASKS_TABLE
> #define CONFIGURE_EXTRA_TASK_STACKS (3 *
> #include <rtems/confdefs.h>
> It says that the application wants a maximum of 4 Classic API tasks
> and 3 of those use stacks of
> twice the minimum.
> No. You can have as many as you have RAM. See libbsp/sparc/shared/
> bspstart.c which
> tries to give the required memory above the heap to the RTEMS
OK, I understand this and it makes sense at all, what I don't
understand is the heap_size variable initialisation.
Thanks for the fast answer.
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