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Date: Wed, 10 Jun 2009 20:27:02 +0100
From: Jamie Lokier <jamie@shareable.org>
Subject: Re: [Qemu-devel] [PATCHv3 03/13] qemu: add routines to manage PCI
	capabilities
Message-ID: <20090610192702.GH7416@shareable.org>
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To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Carsten Otte <cotte@de.ibm.com>, kvm@vger.kernel.org, Glauber Costa <glommer@redhat.com>, Rusty Russell <rusty@rustcorp.com.au>, qemu-devel@nongnu.org, virtualization@lists.linux-foundation.org, Blue Swirl <blauwirbel@gmail.com>, Christian Borntraeger <borntraeger@de.ibm.com>, Paul Brook <paul@codesourcery.com>, Avi Kivity <avi@redhat.com>

Michael S. Tsirkin wrote:
> > I think the right long term answer to all this is a way to get QEMU to
> > dump it's current machine configuration in glorious detail as a file
> > which can be reloaded as a machine configuration.
> 
> And then we'll have the same set of problems there.

We will, and the solution will be the same: options to create devices
as they were in older versions of QEMU.  It only needs to cover device
features which matter to guests, not every bug fix.

However with a machine configuration which is generated by QEMU,
there's less worry about proliferation of obscure options, compared
with the command line.  You don't necessarily have to document every
backward-compatibility option in any detail, you just have to make
sure it's written and read properly, which is much the same thing as
the snapshot code does.

-- Jamie