Re: [PATCH 2/3] qemu: Generate cmd line for pipewire audio backend

On 5/16/23 11:52, Martin Kletzander wrote: > On Thu, May 11, 2023 at 02:14:51PM +0200, Michal Privoznik wrote: >> This is mostly straightforward, except for a teensy-weensy >> detail: usually, there's no system wide daemon running, no system >> wide available socket that anybody could connect to. PipeWire >> uses a per user daemon approach instead. But this in turn means, > > I spent some time thinking about this even after I said "just give it > runtime dir" and now I'm wondering, is this not similar to the dbus > daemon?  When we launch it with a constructed config file for graphics > type='dbus' we could also launch pipewire deamon with our config file > and let qemu connect to that daemon.  I'm not sure what the audio > permissions would look like, but it seems like a less messy approach. And how would then this per-domain pipewire daemon talk to the user session daemon that's actually doing all the mixing? I mean, how would sound from a domain get to speakers/headphones? For dbus it's fairly easy to use, because the socket (and config file) is located under configurable location (cfg->dbusStateDir) and with predictable name (domain short name) AND (more importantly) we have virDomainOpenGraphics() API which then handles virt-viewer connection requests.