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Date: Tue, 07 May 2013 20:23:33 +0200
From: Jan Kiszka <jan.kiszka@siemens.com>
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Subject: Re: [Qemu-devel] [RFC][PATCH 10/15] memory: Rework sub-page handling
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To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Maydell <peter.maydell@linaro.org>, Liu Ping Fan <pingfank@linux.vnet.ibm.com>, qemu-devel <qemu-devel@nongnu.org>, =?UTF-8?B?QW5kcmVhcyBGw6RyYmU=?= =?UTF-8?B?cg==?= <afaerber@suse.de>

On 2013-05-07 19:26, Jan Kiszka wrote:
> Well, the alternative is to handle a sub-page dispatch (ie. calling into
> subpage_[ram_]read/write just like address_space_rw: take the necessary
> lock that protect mapping changes, look into the sub-page and pick up
> the target region, invoke memory_region_ref on it, perform the access
> and unref the region again. Slow, but that's how sub-pages are. And it
> only affects TCG. Hmm, or does your IOMMU core cache translations on a
> per-page base as well?

OK, there is no translation caching in the memory core. So I will
preserve the dispatching functions of sub-pages, just like the term
"sub-page" - along with a comment why we depend on page granularity.

Jan

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