Enhanced stack allocator configuration

[Sebastian Huber]

The RTEMS application configuration may provide a special task stack allocator:

​http://rtems.org/onlinedocs/doc-current/share/rtems/html/c_user/c_user00419.html

CONFIGURE_TASK_STACK_ALLOCATOR may point to a user provided routine to allocate task stacks. The default value for this field is NULL which indicates that task stacks will be allocated from the RTEMS Workspace.

CONFIGURE_TASK_STACK_DEALLOCATOR may point to a user provided routine to free task stacks. The default value for this field is NULL which indicates that task stacks will be allocated from the RTEMS Workspace.

The current structure has two problems:

A) There is no standard way to initialize the allocator
B) The task stack area size is unknown to the allocator and the stack area size is accounted in the work space size estimate (thus the work space is larger than necessary).

To address problem A we should add an optional initialization function:

CONFIGURE_TASK_STACK_ALLOCATOR_INIT may point to a user provided routine to initialize the task stack allocator. The default value for this field is NULL which indicates that task stacks will be allocated from the RTEMS Workspace.

The prototype should be:

void (*stack_allocator_init_hook)(uintptr_t stack_area_size);

The function should be called right before _Thread_Create_idle() in rtems_initialize_data_structures().

To address problem B we should add an additional field to the Configuration:

typedef struct {

void *work_space_start;
uintptr_t work_space_size;
uintptr_t stack_space_size;
[...]
void (*stack_allocator_init_hook)( uintptr_t );
void * (*stack_allocate_hook)( size_t );
void (*stack_free_hook)( void *);
[...]

} rtems_configuration_table;

The confdefs.h must be modified to separate the stack area estimate from the overall work space estimate. In case no stack allocator is configured the work space size is increased by the stack space size.

[Sebastian Huber]

Added stack_space_size field to Configuration.

[Sebastian Huber]

Configuration changes.

[Sebastian Huber]

Configuration changes.

[Sebastian Huber]

Documentation changes.

[Sebastian Huber]

​http://git.rtems.org/rtems/commit/?id=9fa3cf0db84cbabdb639cdeb7565f4c3ca3bc562

[Gedare Bloom]

Replace Version=HEAD with Version=4.11 for the tickets with Milestone >= 4.11