On Wed, Jun 09, 2021 at 12:29:58PM +0100, Daniel P. Berrangé wrote: > On Wed, Jun 09, 2021 at 01:24:05PM +0200, Gerd Hoffmann wrote: > > On Wed, Jun 09, 2021 at 12:02:40PM +0200, Thomas Huth wrote: > > > Libvirt's "domcapabilities" command has a way to state whether > > > certain graphic frontends are available in QEMU or not. Originally, > > > libvirt looked at the "--help" output of the QEMU binary to determine > > > whether SDL was available or not (by looking for the "-sdl" parameter > > > in the help text), but since libvirt stopped doing this analysis of > > > the help text, the detection of SDL is currently broken, see: > > > > > > https://bugzilla.redhat.com/show_bug.cgi?id=1790902 > > > > > > QEMU should provide a way via the QMP interface instead. The simplest > > > way, without introducing additional commands, is to make the DisplayType > > > enum entries conditional, so that the enum only contains the entries if > > > the corresponding CONFIG_xxx switches have been set. > > > > Hmm, that'll break for the "dnf remove qemu-ui-sdl" case ... > > Note tht libvirt invalidates its cache of QEMU capabilities when it > sees the /usr/lib64/qemu directory timestamp change. So it ought to > pick up changes caused by installing/removing QEMU modules, and apply > this to future queries for domcapabilities, or when starting future > QEMU guests. That'll work fine for modules implementing qom objects / devices, because the list of available objects changes accordingly and libvirt can see that. The #if CONFIG_SDL approach will not work because qemu will continue to report sdl as supported even when the sdl module is not installed any more. take care, Gerd
