Re: [PATCHv7 11/19] x86/mm: Make STACK_TOP_MAX dynamic

[Ingo Molnar]

* Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> wrote:

> For boot-time switching between paging modes, we need to be able to
> change STACK_TOP_MAX at runtime.
> 
> The change is trivial and it doesn't affect kernel image size.
> 
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
> ---
>  arch/x86/include/asm/processor.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
> index 3fa26a61eabc..fa9300ccce1b 100644
> --- a/arch/x86/include/asm/processor.h
> +++ b/arch/x86/include/asm/processor.h
> @@ -871,7 +871,7 @@ static inline void spin_lock_prefetch(const void *x)
>  					IA32_PAGE_OFFSET : TASK_SIZE_MAX)
>  
>  #define STACK_TOP		TASK_SIZE_LOW
> -#define STACK_TOP_MAX		TASK_SIZE_MAX
> +#define STACK_TOP_MAX		(pgtable_l5_enabled ? TASK_SIZE_MAX : DEFAULT_MAP_WINDOW)

While it's only used once in fs/exec.c, why doesn't it affect kernel image size?

Thanks,

	Ingo