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Subject: Re: [PATCH] ppc64: 64K pages support
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Christoph Hellwig <hch@lst.de>
Cc: Andrew Morton <akpm@osdl.org>, linuxppc64-dev <linuxppc64-dev@ozlabs.org>,
       Linus Torvalds <torvalds@osdl.org>,
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Date: Sat, 05 Nov 2005 11:44:47 +1100
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On Sat, 2005-11-05 at 01:38 +0100, Christoph Hellwig wrote:
> So how does the 64k on 4k hardware emulation work?  When Hugh did
> bigger softpagesize for x86 based on 2.4.x he had to fix drivers all
> over to deal with that.

What was the problem with drivers ? On ppc64, it's all hidden in the
arch code. All the kernel sees is a 64k page size. I extended the PTE to
contain tracking informations for the 16 sub pages (HPTE bits & hash
slot index). Sub pages are faulted on demand and flushed all at once,
but it's all transparent to the generic code.

Ben.