On Thu, May 07, 2020 at 16:49:14 +0200, Gerd Hoffmann wrote: > Hi, > > For usb device pass-through (aka -device usb-host) it would be very > useful to pass file handles from libvirt to qemu. The workflow would > change from ... > > (1) libvirt enables access to /dev/usb/$bus/$dev > (2) libvirt passes $bus + $dev (using hostbus + hostaddr properties) > to qemu. > (3) qemu opens /dev/usb/$bus/$dev > > ... to ... > > (1) libvirt opens /dev/usb/$bus/$dev > (2) libvirt passes filehandle to qemu. > > Question is how can we pass the file descriptor best? My idea would be > to simply add an fd property to usb-host: > > * Coldplug would be "-device usb-host,fd=<nr>" (cmd line). > * Hotplug would be "device_add usb-host,fd=<getfd-name>" (monitor). We have prior art for both approaches so it's fine. > > Will that work from libvirt point of view? Sure! Just please make sure that the new approach is detectable somehow. Either via device-list-properties or query-qmp-schema. > Or does anyone have an better idea? > > thanks, > Gerd > > PS: background: https://bugzilla.redhat.com/show_bug.cgi?id=1595525 >
