Why is it that some kind of USB devices (e.g. web camera) are exclusively assigned* to a KVM virtual machine, while others (e.g. mouse, keyboard) can be shared between host/VM/other VMs?
- it must be added explicitly (Add Hardware in Virtual Machine Manager) -- while the mouse/keyboard "just work"
- while the guest is running, that device is not available on the host -- mouse/keyboard are shared seamlessly
- the guest does not even start up, if that device (e.g. the webcam) is not plugged in -- I did not try this, but I suppose VM would start without keyboard/mouse
- I think removing that device causes the guest to crash (I vaguely recall accidentally having done this once, and now I don't want to try it again), even if the device is not in use -- on the host, the webcam can be removed without compromising the stability of the system