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Date: Wed, 19 Nov 2014 17:12:30 +0200
From: "Michael S. Tsirkin" <mst@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH 2/5] exec: qemu_ram_alloc_device,
	qemu_ram_resize
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To: Peter Maydell <peter.maydell@linaro.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>, QEMU Developers <qemu-devel@nongnu.org>, "Dr. David Alan Gilbert" <dgilbert@redhat.com>, Juan Quintela <quintela@redhat.com>

On Wed, Nov 19, 2014 at 02:10:36PM +0000, Peter Maydell wrote:
> On 19 November 2014 14:07, Juan Quintela <quintela@redhat.com> wrote:
> > My understanding is that it is a "trick".  We have internal memory for a
> > device that is needed for the emulation, but not showed to the guest.
> > And it is big enough that we want to save it during the "live" stage of
> > migration, so we mark it as RAM.  if it is somekind of cash, we can just
> > enlarge it on destination, and it don't matter.  If this has anything
> > different on the other part of the RAM, we are on trouble.
> 
> Would it be feasible to just have the migration code provide
> an API for registering things to be migrated in the live
> migration stage, rather than creating memory regions which
> you can't actually use for most of the purposes the memory
> region API exists for?
> 
> -- PMM

We could, it's just much more work, touching a lot more
places.

-- 
MST