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arch: arm: documentation improvements for _ARCH_THREAD_STACK_SIZEOF()

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This commit corrects and improves the documentation for the
convenience macro _ARCH_THREAD_STACK_SIZEOF(sym). It stresses
that the returned size is guaranteed to match the amount of
stack that is available for the thread, that is, excluding any
areas not directly usable, e.g. a Stack Guard.

Signed-off-by: Ioannis Glaropoulos <Ioannis.Glaropoulos@nordicsemi.no>
This commit is contained in:
Ioannis Glaropoulos 2019-03-08 09:06:38 +01:00 committed by Andrew Boie
parent 4e4048fadf
commit 8cbba1e2ee
1 changed files with 7 additions and 3 deletions
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10
include/arch/arm/arch.h
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@ -224,17 +224,21 @@ extern "C" {
* since the underlying implementation may actually create something larger
* (for instance a guard area).
*
* The value returned here is guaranteed to match the size of the stack that
* is available for the thread, i.e. excluding the size of areas that are not
* to be used (for instance the guard area).
*
* The value returned here is NOT guaranteed to match the 'size' parameter
* passed to K_THREAD_STACK_DEFINE and related macros.
*
* In the case of CONFIG_USERSPACE=y and
* CONFIG_MPU_REQUIRES_POWER_OF_TWO_ALIGNMENT, the size will be larger than the
* requested size.
* CONFIG_MPU_REQUIRES_POWER_OF_TWO_ALIGNMENT=y, the returned size will be
* smaller than the requested 'size'.
*
* In all other configurations, the size will be correct.
*
* @param sym Stack memory symbol
* @return Size of the stack
* @return Actual size of the stack available for the thread
*/
#define _ARCH_THREAD_STACK_SIZEOF(sym) (sizeof(sym) - MPU_GUARD_ALIGN_AND_SIZE)