sparc stack and heap

[Aleix Conchillo Flaqué]

I'll answer my self, task stacks are allocated in the heap. Right?

Cheers,

aleix

On 25 Jul 2006, at 14:31, Aleix Conchillo Flaqué wrote:

>
> 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 -  
> STACK_SIZE;
> 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 *  
>> RTEMS_MINIMUM_STACK_SIZE)
>>
>> #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  
>> Workspace.
>>
>
> 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.
>
> Best regards,
>
> aleix