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Subject: Re: [PATCH] swiotlb: make swiotlb allocation functions
	architecture-specific
From: Ian Campbell <Ian.Campbell@eu.citrix.com>
To: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
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Date: Fri, 22 May 2009 12:46:06 +0100
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On Fri, 2009-05-22 at 07:13 -0400, FUJITA Tomonori wrote:
> On Thu, 21 May 2009 17:15:25 +0100
> Ian Campbell <ian.campbell@citrix.com> wrote:
> 
> > Some architectures need to allocate memory to be used as a swiotlb in
> > a special manner.
> 
> Hmm, what architectures need a special manner? I guess only Xen.

The x86 architecture, when running as a paravirtualised guest under Xen,
needs it. I guess ia64 might need it for similar reasons, I'm not sure.

How does the fact that x86-Xen is (currently) the only user invalidate
the requirement? You seem to have a knee-jerk reaction to anything which
might be useful to Xen and I really don't understand why that should be
the case.

We are talking about an initialisation path and we are not talking about
changes which completely obscure all meaning or anything. The semantics
of the API are pretty clear, I think.

Ian.