Question on hugepages_supported()

Question on hugepages_supported()

[Christophe LEROY]

In include/linux/hugetlb.h, we find the following statement

#ifndef hugepages_supported
/*
  * Some platform decide whether they support huge pages at boot
  * time. Some of them, such as powerpc, set HPAGE_SHIFT to 0
  * when there is no such support
  */
#define hugepages_supported() (HPAGE_SHIFT != 0)
#endif

But in arch/powerpc/include/asm/page.h we find:

#ifdef CONFIG_HUGETLB_PAGE
extern unsigned int HPAGE_SHIFT;
#else
#define HPAGE_SHIFT PAGE_SHIFT
#endif


Is that correct ? SHouldn't HPAGE_SHIFT be defined to 0 when 
CONFIG_HUGETLB_PAGE is not defined ?

Christophe

Re: Question on hugepages_supported()

[Aneesh Kumar K.V]

Christophe LEROY <christophe.leroy@c-s.fr> writes:

> In include/linux/hugetlb.h, we find the following statement
>
> #ifndef hugepages_supported
> /*
>   * Some platform decide whether they support huge pages at boot
>   * time. Some of them, such as powerpc, set HPAGE_SHIFT to 0
>   * when there is no such support
>   */
> #define hugepages_supported() (HPAGE_SHIFT != 0)
> #endif
>
> But in arch/powerpc/include/asm/page.h we find:
>
> #ifdef CONFIG_HUGETLB_PAGE
> extern unsigned int HPAGE_SHIFT;
> #else
> #define HPAGE_SHIFT PAGE_SHIFT
> #endif
>
>
> Is that correct ? SHouldn't HPAGE_SHIFT be defined to 0 when 
> CONFIG_HUGETLB_PAGE is not defined ?
>

But then hugepages_supported() is only defined if HUGETLB_PAGE is
enabled. So yes we can possibly say HPAGE_SHIFT = 0 if HUGETLB is
disabled, I am not sure it has any impact with the current code ?


-aneesh