[Qemu-discuss] What is the current state of the various usb implementations?

[tom289332]

Hello,

Looking at `qemu-kvm -device ?`, there seem to be multiple usb implementations:

ich9-usb-uhci2
ich9-usb-uhci3
ich9-usb-uhci1
piix3-usb-uhci
piix4-usb-uhci
vt82c686b-usb-uhci
ich9-usb-ehci1
usb-ehci
nec-usb-xhci

Are they all fully implemented and stable? If not, what is the state of each?
People who have used one or more of them a lot, could you share your experience?
Also what is the difference between the three 'ich9's?

Thanks,
Tom