On Mon, 21 Nov 2016, Paul Durrant wrote: > > -----Original Message----- > > From: Pasi Kärkkäinen [mailto:pasik@iki.fi] > > Sent: 19 November 2016 10:57 > > To: Dario Faggioli > > Cc: Konrad Rzeszutek Wilk ; Paul Durrant > > ; Anthony Perard ; > > xen-devel ; Stefano Stabellini > > ; Ian Jackson ; Roger Pau > > Monne > > Subject: Re: [Xen-devel] Wondering about cirris and stdvga > > > > On Fri, Nov 18, 2016 at 07:04:15PM +0100, Dario Faggioli wrote: > > > Sending again, this time, with Anthony's and xen-devel address spelled > > > right. Sorry!! :-( > > > ------------------------------------------- > > > Hello to you, various pseudo-random people, > > > > > > It's not my field of expertise, so bear with me, at least a little bit > > > (and, Konrad, you help me, or there will be consequences! :-D) > > > > > > So, I and Konrad recently discovered --while testing the about to be > > > released Fedora 25 as a Xen guest-- that the Cirrus emulated graphic > > > card that we consume from QEMU for HVM guests is broken on Wayland. > > > > > > We just discovered it because Fedora 25 uses Wayland by default, but it > > > appears not to be something new: > > > > > > https://bugzilla.redhat.com/show_bug.cgi?id=1227770 > > > > > > And at least from what we see in that bugreport, not much has happened > > > so far. > > > > > > Using "vga='stdvga'" in the config file, or even "vga='qxl'" make > > > things work again. Disabling Wayland in the guest also works (i.e., if > > > not using Wayland, Cirrus is ok). And that's what made us think that > > > it's probably a Wayland issue. > > > > > > I've tried the same on KVM, and the situation is identical > > > (Cirrus+Wayland=breaks, whatever-else+Wayland=works, > > > Cirrus+Xorg=works). > > > > > > I've also read around that these days, e.g., stdvga is at least as good > > > as cirrus, performance wise, that cirrus is broken and impossible to > > > fix (because it is the hardware that it's emulating that was broken), > > > that stdvga enables better screen resolution in guests, etc. > > > > > > I'm not sure about these claims, in particular the performance one, is > > > probably pretty hard to verify. And as I said, it's not my field. > > > > > > Still I thought it could be worthwhile to at least bring this up: > > > should we start to consider changing the default from cirrus to stdvga > > > (or something else)? > > > > > > > There's multiple things here.. > > > > 1) Yes, +1, let's change the Xen HVM default to "stdvga". > > > > In general std-vga also gets a +1 from me, but I have recently found that a Windows Server 2008 guest does not boot (ar at least the display freezes on boot) when using std-vga with QEMU trad but everything is fine with Cirrus... so probably worth making the default dependent on which QEMU is being used. Never had any issues with std-vga on upstream QEMU. In all fairness, I think it's worth mentioning that the original reason for defaulting to Cirrus was that Windows XP wasn't able to boot on stdvga either.