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Date: Wed, 27 Aug 2014 09:58:33 +0100
From: "Daniel P. Berrange" <berrange@redhat.com>
Message-ID: <20140827085832.GA15714@redhat.com>
References: <1408789147-18675-1-git-send-email-lersek@redhat.com>
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In-Reply-To: <1408789147-18675-1-git-send-email-lersek@redhat.com>
Subject: Re: [Qemu-devel] [PATCH 0/2] pflash (UEFI varstore) migration
	shortcut for libvirt
Reply-To: "Daniel P. Berrange" <berrange@redhat.com>
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To: Laszlo Ersek <lersek@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>, Juan Quintela <quintela@redhat.com>, Michal Privoznik <mprivozn@redhat.com>, David Gilbert <dgilbert@redhat.com>, qemu devel list <qemu-devel@nongnu.org>, Stefan Hajnoczi <stefanha@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>

On Sat, Aug 23, 2014 at 12:19:05PM +0200, Laszlo Ersek wrote:
> Libvirt is growing support for x86_64 OVMF guests:
> 
> http://www.redhat.com/archives/libvir-list/2014-August/msg01045.html
> 
> An important feature of such guests is the persistent store for
> non-volatile UEFI variables. This is implemented with if=pflash drives.
> The referenced libvirt patchset sets up the varstore files for
> single-host use.
> 
> Wrt. migration, two choices have been considered:
> (a) full-blown live storage migration for the drives backing pflash
>     devices,
> (b) vs. a shortcut that exploits the special nature of pflash drives
>     (namely, their minuscule size, and a RAMBlock that keeps the full
>     contents of each pflash drive visible to the guest, and is
>     up-to-date, at all times.)

So, IIUC, with option b), libvirt will merely need to make sure that
the NVRAM var store file exists with the right size. QEMU will then
just 'do the right thing' for migration copying across the contents ?
If so that sounds nice to me.

Regards,
Daniel
-- 
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