I try to pass-through an usb serial device (US Robotics modem; cdc-acm kernel module) to a linux guest. Both, host and guest are based on the latest debian 32bit 2.6.30 kernel version.
The modem gets correctly passed through to the guest. So, the guest sees the usb device. The host doesn't have the cdc-acm kernel module loaded. But the guest won't be able to use the modem (can't ring somebody).
If I try the same with cdc-acm loaded within host, all works fine.
It's worth to mention that with an older qemu-kvm or kvm version the guest was able to use the modem.
The cpu is an Intel DualCore. If you need more informations, feel free to contact me.