To: Christoph Hellwig <hch@infradead.org>
cc: Ian Pratt <Ian.Pratt@cl.cam.ac.uk>, linux-kernel@vger.kernel.org,
       akpm@osdl.org, Keir.Fraser@cl.cam.ac.uk, Christian.Limpach@cl.cam.ac.uk,
       Ian.Pratt@cl.cam.ac.uk
Subject: Re: [patch 1] Xen core patch : ptep_establish_new 
In-reply-to: Your message of "Thu, 18 Nov 2004 10:11:09 GMT."
             <20041118101109.GA20859@infradead.org> 
Date: Thu, 18 Nov 2004 10:26:32 +0000
From: Ian Pratt <Ian.Pratt@cl.cam.ac.uk>
Message-Id: <E1CUjUn-0005KZ-00@mta1.cl.cam.ac.uk>
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1208
Lines: 28

> On Wed, Nov 17, 2004 at 11:46:50PM +0000, Ian Pratt wrote:
> > 
> > This patch adds 'ptep_establish_new', in keeping with the
> > existing 'ptep_establish', but for use where a mapping is being
> > established where there was previously none present. This
> > function is useful (rather than just using set_pte) because
> > having the virtual address available enables a very important
> > optimisation for arch-xen. We introduce
> > HAVE_ARCH_PTEP_ESTABLISH_NEW and define a generic implementation
> > in asm-generic/pgtable.h, following the pattern of the existing
> > ptep_establish.
> 
> What would be the problem of always passing the virtual address to
> ptep_establish?  We already have a rather twisted maze of pte manipulation
> macros.

ptep_establish already takes a virtual address. Perhaps you mean
'set_pte'? That would work, but is a much bigger change that
would impact all architectures. I think introducing
ptep_establish_new is cleaner.

Ian

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