Hi, > > I'd like to have some way to assign tags such as seat=foo or head=1 to > > devices. Preferably in some way which can easily picked up with udev > > rules, so it is easily usable by system-logind and Xorg server. > > The only current example of seat autoconfiguration is for the usb hubs > from displaylink I think, which have video/audio/ethernet/usb behind a > hub that udev detects as being part of a seat, I'd need to look up the > specifics,
udev can match upstream devices, so it's easy to tag all devices below the usb hub as belonging to the seat. > > We have virtio devices (virtio-gpu for example). For these it is easy, > > we can put something into the virtio protocol, and the guest driver can > > create a sysfs file where udev/systemd can pick it up. > > > > We have pci devices (cirrus for example). One idea for them would be to > > create a vendor-specific pci capabiliy for tags. Probably needs some > > small utility to read them, or kernel driver support to export them via > > sysfs. > > > > We have usb devices (kbd/mouse/tablet). We could put something into the > > string table, or have some vendor-specific descriptor. Same problem > > here, not easy accessible, needs a tool or kernel support. > > > > Comments? Better ideas? Other suggestions? > > It does seems like tagging the devices somehow would be better than providing > a seat device, like we could in theory have a pci and usb controller > per seat, and > have devices move around between them, this would be like what we for > the real hw, > however per-device tags does look like it might be nicer in the long run. I've been thinking about this too. Use a pci-bridge, then group the devices belonging to the seat below the pci-bridge for easy udev matching. That doesn't help for the multihead case though. And we have to tag the devices for qemu's internal usage (host-side input routing) anyway. Thats why I think the tagging will work better. cheers, Gerd
