On Mon, Feb 09, 2026 at 14:58:56 +0000, Andrea Bolognani wrote: > On Fri, Feb 06, 2026 at 10:27:39AM +0100, Peter Krempa wrote: > > On Mon, Jan 12, 2026 at 15:49:16 +0100, Andrea Bolognani via Devel wrote: > > > The current behavior is to error out, but that's not very helpful. > > > Automatically add the necessary USB controller instead. > > > > IMO this creates the same situation we're in currently with the addition > > of SCSI controllers. We add 'lsilogic' as controller if you don't have > > any which is sub-optimal, but it's the default and the behaviour we've > > standardized on thus we can't really change it. > > > > The auto-added USB controller will be likely sub-optimal either now or > > in the future. While it seems helpful to add it it can create headaches. > > > > To me it seems that the users simply should add the controller manually > > if the platform doesn't have one. > > In many cases users will want to add the controller manually even for > architectures that do provide it by default, specifically because the > chosen model might be suboptimal. This is exactly what virt-manager > already does, both for SCSI and USB controllers. > > The fact that the behavior of automatically adding a controller when > a device that needs it is present in the domain XML is already well > established for SCSI and others is IMO good motivation for doing the
As I've written above I don't consider it beneficial that we add the now-bad SCSI controller automatically. In fact I'd personally prefer to get an (actionable) error telling me to add a controler instead of adding the wrong one and claiming success. It might seem like a good user experience to add one but in the end the configuration will be worse than if the user did it manually. > same with USB controllers, even if there are some known potential > pitfalls with the approach. Thus I don't think we should extend this IMO wrong approach to things.
