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From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
To: Christophe LEROY <christophe.leroy@c-s.fr>
Cc: "linuxppc-dev\@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>
Subject: Re: Question on hugepages_supported()
In-Reply-To: <bbc6ae12-1705-32e1-109b-baefead9444b@c-s.fr>
References: <bbc6ae12-1705-32e1-109b-baefead9444b@c-s.fr>
Date: Wed, 02 Aug 2017 12:58:38 +0530
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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