On Wed, Jul 13, 2022 at 07:00:17PM +0800, Han Han wrote: > Hello, > I found that the default USB controller for q35 machine type is qemu-xhci > while for pc it is piix3-uhci. Here are the results(on qemu-kvm-7.0.0 > qemu-kvm-7.0.0): > ➜ ~ cat /tmp/usb.xml > <domain type="kvm"> > <name>USB</name> > <uuid>1a81d4ef-6537-4ae8-b257-8a15e0c0525f</uuid> > <memory>2097152</memory> > <currentMemory>2097152</currentMemory> > <vcpu>1</vcpu> > <os> > <type arch="x86_64" machine="q35">hvm</type> > <boot dev="hd"/> > </os> > <devices> > <emulator>/usr/libexec/qemu-kvm</emulator> > </devices> > </domain> > > ➜ ~ virsh define /tmp/usb.xml && virsh dumpxml USB|grep usb > Domain 'USB' defined from /tmp/usb.xml > > <controller type='usb' index='0' model='qemu-xhci'> > > > ➜ ~ cat /tmp/usb-pc.xml > <domain type="kvm"> > <name>USB</name> > <uuid>1a81d4ef-6537-4ae8-b257-8a15e0c0525f</uuid> > <memory>2097152</memory> > <currentMemory>2097152</currentMemory> > <vcpu>1</vcpu> > <os> > <type arch="x86_64" machine="pc">hvm</type> > <boot dev="hd"/> > </os> > <devices> > <emulator>/usr/libexec/qemu-kvm</emulator> > </devices> > </domain> > > ➜ ~ virsh define /tmp/usb-pc.xml && virsh dumpxml USB|grep usb > Domain 'USB' defined from /tmp/usb-pc.xml > > <controller type='usb' index='0' model='piix3-uhci'> > > And the default usb controller for q35 has been added since: > ed2049ea19 qemu: auto-add generic xhci rather than NEC xhci to Q35 domains > > As I know, pc machine supports qemu-xhci as well. Morever, the > performance of qemu-xhci is better than piix3-uhci. So why not update the > default usb controller of pc machine type to qemu-xhci? I think we can > improve it here. A qemu-xhci controller can be added to any x86 machien type regardless of the default, and most mgmt apps will do exactly that. With 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 :|
