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<div><br></div><div dir="auto" style="font-size:100%;color:#000000"><div>-------- Original message --------</div><div>From: Alex Williamson <alex.williamson@redhat.com> </div><div>Date: 07/10/2020 18:08 (GMT+00:00) </div><div>To: Steven Newbury <steve@snewbury.org.uk> </div><div>Cc: Peter Krempa <pkrempa@redhat.com>, libvir-list@redhat.com </div><div>Subject: Re: [PATCH] Support x-vga=on for PCI host passthrough devices </div><div><br></div></div>On Wed, 07 Oct 2020 14:20:21 +0100<br dir="auto">Steven Newbury <steve@snewbury.org.uk> wrote:<br dir="auto"><br dir="auto">> On Wed, 2020-10-07 at 15:07 +0200, Peter Krempa wrote:<br dir="auto">> > On Wed, Oct 07, 2020 at 13:59:35 +0100, Steven Newbury wrote: <br dir="auto">> > > When using a passthrough GPU with libvirt there is no option to<br dir="auto">> > > pass "x-vga=on" to the device specification. This means legacy <br dir="auto">> > <br dir="auto">> > Please note that we don't add support for experimental qemu features<br dir="auto">> > (prefixed with "x-") until they are deemed stable and the x- is<br dir="auto">> > removed, so this patch can't be accepted in this form.<br dir="auto">> > <br dir="auto">> Okay, so should I bug qemu to promote the feature to stable? It's been<br dir="auto">> like that forever, it's certainly not a new feature:<br dir="auto">> <br dir="auto">> https://github.com/qemu/qemu/commit/f15689c7e4422d5453ae45628df5b83a53e518ed<br dir="auto">> <br dir="auto">> So it's been that way for 8 years!<br dir="auto"><br dir="auto">It's that way upstream because VGA routing is a nightmare, it's<br dir="auto">essentially broken on any system with Intel graphics because the device<br dir="auto">always has VGA regions routed to itself. That problem is not getting<br dir="auto">better, but the demand for VGA is getting less, so there's very little<br dir="auto">incentive to work on the problem rather than just letting it die out<br dir="auto">once nobody cares about VGA. Any 600 series or newer GeForce card<br dir="auto">should have a UEFI ROM available. Also note that VGA support can be<br dir="auto">configured both as a module option of vfio-pci and a build option, so<br dir="auto">there's no guarantee that a display class device will have the VGA<br dir="auto">regions available for QEMU to use this option. Thanks,<br dir="auto"><br dir="auto">I'm still going to fix up my patch even if it's not going to get committed. It's very useful for me, my old nvidia card doesn't work without it, and I also need it for seabios/dos compatibility with my ATIs. In fairness, I haven't tried it with my Intel, it's too old to support the new vGPU stuff and I need to see what I'm typing! ;-)<div dir="auto"><br></div><div dir="auto">For what it's worth, I had no trouble with GPU passthrough once I realised it needed x-vga=on. VGA arbitration was automatically switched. It's been rock solid stability wise, although the 8800 has horrible VGA/DOS performance. Windows10 runs like on bare metal.</div><div dir="auto"><br></div></body></html>