On Thu, Jan 25, 2018 at 05:45:51PM +0100, Andrea Bolognani wrote: > Basically all existing guest types, regardless of the architectur, > get both a USB controller and a virtio memory balloon by default. > > s390 guests are an exception, for the very good reason that they > don't support USB at all; the other exception is aarch64/virt > guests, but in the latter case isn't a compelling reason for them > to deviate from the widely adopted convention, especially since: > > * x86/q35 guests, which aarch64/virt guests are for the most > part identical to, add these devices by default; > * it's trivial to opt out of both default devices by setting > model='none'; Except that this requires code changes to downstream applications to actually do this now, otherwise guests that they were expecting to not have USB for, now suddenly get it. > * higher level applications such as Nova expect at least the > USB controller to be present. This doesn't really help nova in practice, because it needs to operate correctly with pre-existing libbvirt releases, and even on x86 it should not be relying on the default USB1 controller, but rather adding a USB2 or USB3 controller. > So add it by default for newly-defined guests. Existing guests > will, of course, be left unchanged. That is still harmful, because an existing mgmt application release that runs on new libvirt has its guest configs suddenly changed, especially if using transient guests. > Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1538637 I consider that bug wontfix. It is just exchanging one set of problems for a different set of problems. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :| -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list
