Re: [PATCH v2 08/17] tests: Add usb-legacy-device

On Wed, Feb 14, 2024 at 18:11:15 +0100, Andrea Bolognani wrote: > This provides coverage for the scenario in which an attempt is > made to use a USB device together with the legacy USB controller. > > Note that, while the test case passes, the configuration it > produces doesn't actually work: > > $ qemu-system-x86_64 -M pc -usb -device usb-tablet,bus=usb.0 > Bus 'usb.0' not found > > This is because the bus created by the legacy USB controller is > automatically assigned ID "usb-bus.0", but libvirt doesn't take > this into consideration when assigning addresses to USB devices. > > In other words, the legacy USB controller will only work as long > as no attempt is made to attach devices to it, which arguably > doesn't make for a very useful controller. Looking at the history the change of the bus name is documented in commit f9618633a86cc74b33f178f05154d4edbc08c0fc : usb: update docs for bus name change At some point the default usb bus name changed from 'usb.0' to 'usb-bus.0' (probably as part of the qom conversion). Update the usb documentation accordingly. Released in qemu-1.5.0. The most likely commit which did the change was 0d936928ef87ca1bb7b41b5b89c400c699a7691c ("convert busses to QOM")

Thus arguably we can remove support for '-usb' at least for x86_64, but almost certainly for anything else too.