Re: [libvirt] [RFC] default video device type
On Mon, Oct 07, 2019 at 02:56:11PM +0200, Pavel Mores wrote:
Hi,
I'm looking into fixing
https://bugzilla.redhat.com/show_bug.cgi?id=1668141
(as a short summary, if a graphics device is added to XML that has no video
device, libvirt automatically adds a video device which is always of type
'cirrus' - even if the underlying qemu doesn't support cirrus).
I'm able to affect the behaviour in question by using qemu capabilities in
qemuDomainDeviceVideoDefPostParse(), see proof-of-concept change in [1]. I
have a couple of questions though:
1) is this a proper place and approach to fix the bug?
I don't think so because the guest ABI could change. Imagine there is an
application that just starts a simple VM (with graphics with no model) and out
of nowhere (after a long time) they upgrade libvirt and qemu and the VM will
look differently.
2) what would be the full specification of expected behaviour? The
bug report
only states that the video type shouldn't be cirrus but doesn't say what it
should be. [2] gives some information about the order of preference of video
device types but I was wondering if there are any opinions about this on this
list?
Reading the BZ it looks to me like virt-manager should allow choosing cirrus and
the different default could be chosen in virt-manager. The BZ is not well
described, to be honest.
Martin
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