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.
>
> Signed-off-by: Andrea Bolognani <abologna@xxxxxxxxxx>
> ---
> .../usb-legacy-device.x86_64-latest.args | 33 +++++++++++++++++++
> .../usb-legacy-device.x86_64-latest.xml | 30 +++++++++++++++++
> tests/qemuxmlconfdata/usb-legacy-device.xml | 15 +++++++++
> tests/qemuxmlconftest.c | 5 +++
> 4 files changed, 83 insertions(+)
> create mode 100644 tests/qemuxmlconfdata/usb-legacy-device.x86_64-latest.args
> create mode 100644 tests/qemuxmlconfdata/usb-legacy-device.x86_64-latest.xml
> create mode 100644 tests/qemuxmlconfdata/usb-legacy-device.xml
Preliminarily:
Reviewed-by: Peter Krempa <pkrempa@xxxxxxxxxx>
and I'll see how this changes after the patches reworking the code.
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