linux-kernel - Re: [PATCH v3 2/3] powerpc: get hugetlbpage handling more generic

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Message-Id: <878tulw5p8.fsf@linux.vnet.ibm.com>
Date:   Wed, 21 Sep 2016 22:28:11 +0530
From:   "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>
To:     Christophe Leroy <christophe.leroy@....fr>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Scott Wood <oss@...error.net>
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH v3 2/3] powerpc: get hugetlbpage handling more generic

Christophe Leroy <christophe.leroy@....fr> writes:

> Today there are two implementations of hugetlbpages which are managed
> by exclusive #ifdefs:
> * FSL_BOOKE: several directory entries points to the same single hugepage
> * BOOK3S: one upper level directory entry points to a table of hugepages
>
> In preparation of implementation of hugepage support on the 8xx, we
> need a mix of the two above solutions, because the 8xx needs both cases
> depending on the size of pages:
> * In 4k page size mode, each PGD entry covers a 4M bytes area. It means
> that 2 PGD entries will be necessary to cover an 8M hugepage while a
> single PGD entry will cover 8x 512k hugepages.
> * In 16 page size mode, each PGD entry covers a 64M bytes area. It means
> that 8x 8M hugepages will be covered by one PGD entry and 64x 512k
> hugepages will be covers by one PGD entry.
>
> This patch:
> * removes #ifdefs in favor of if/else based on the range sizes
> * merges the two huge_pte_alloc() functions as they are pretty similar
> * merges the two hugetlbpage_init() functions as they are pretty similar

Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@...ux.vnet.ibm.com>


>
> Signed-off-by: Christophe Leroy <christophe.leroy@....fr>
> ---

-aneesh