# USB root passthrough with qemu?

## _______0

hi,

I can passthrough individual devices already plugged in, but that's no very practical in all scenarios. I had an idea about passing through the entire USB root hub so the guest can get USB on demand. Trying to add this to qemu's usb device gave me some memory errors.

1d6b:0001 Linux Foundation 1.1 root hub

1d6b:0002 Linux Foundation 2.0 root hub

My idea was to launch a guest that has temporary control of CD/DVD, USB, sound card. Net is not necessary as default is just fine for this purpose.

How to achieve this? Thanks.

----------

## syn0ptik

yes, but only if it connected -usbdevice 058f:6366

----------

## _______0

 *syn0ptik wrote:*   

> yes, but only if it connected -usbdevice 058f:6366

 

Yes what? And I don't have that usb device, at least is not showing with lusb.

----------

## 222697

Same problem here- USB pass-through only works if I start the qemu kvm when the USB printer (vendor/product ID 04e8:3242) is switched on and therefore shown in lsusb on the host. Then it is available in the started VM. But when I switch the usb printer attached to the host off, it disappears in lsusb both on the host and the VM (as expected) but when I switch the USB printer on again, it is shown on the host and also on the QEMU Monitor (Crtl Alt Shift 2 -> info usbhost), but in the VM lsusb does not show it again- so USB pass-through does not work. It workes with a previous Version of qemu (1.0 or something).

I start qemu with this option:

-usb -usbdevice host:04e8:3242

Linux 3.10.7-gentoo

qemu 1.5.3

Any idea how to solve this?

I did not even find a bug report.

EDIT:

Problem was not even fixed with qemu-2.0.0. Disappointing.

----------

