Re: [PATCH 0/3] domain capabilites improvements

On 9/8/22 01:52, Peter Krempa wrote: > On Wed, Sep 07, 2022 at 15:20:44 -0600, Jim Fehlig wrote: > > On 9/6/22 14:42, Jim Fehlig wrote:

> In cases where a command line option parser in qemu was implemented via > the modern QOM based approach, but at the same time is not runtime > configurable or queryable via the monitor it's not possible for libvirt > to detect the options. > > Historically command line arguments could be queried via > 'query-command-line-options' command but that was deemed to be > un-extendible and new code is not getting coverage. At the same time > libvirt is trying to decrease the reliance on the command to allow > deprecation and promote some form of replacement. > > We had a similar problem for graphics options, which was side-stepped by > implementing 'query-display-options' which in turn exposed all the > objects in the QMP schema (query-qmp-schema) which allowed us to detet > graphics related functionality. > > At this point we e.g. assume that the modern -audiodev is present. For > few specific configs we validate that the appropriate graphics protocol > is used for the VM but don't validate anything else. > > For your specific query, the spice backend for audio is allowed only > when spice video is enabled anyways, so the capability you are > suggesting does not seem to be that much interesting as the decision can > be based on the graphics protocol support. IIUC, it is possible to have a qemu installation with spice video support but without the audio-spice module. If that is the case, seems we need to report the available audio backends in domcaps.