Comment 0 for bug 258771

Binary package hint: kvm

When accessing a USB device on the host, the entire guest OS slows down to a crawl, to the point where mouse navigation becomes impossible. stracing KVM shows many USBDEVFS_BULK ioctls returning -ETIMEDOUT, corresponding to the frequent pauses of the guest.

Despite this, the device actually does work. In my case, it was a 3G modem, and sending even one "AT" command slowed down the entire guest for minutes at a time, but eventually it returned to normal operation.

I believe this affects qemu as well, but I haven't verified it myself. There is at least one independent report at http://qemu-forum.ipi.fi/viewtopic.php?f=4&t=4559 which claims this is a problem with USB devices which provide multiple interfaces.