Thank you for your answer, but that's exactly the doc I've followed.
In fact  I've digged a little more : my wifi dongle uses the RT73 driver which uses the serialmonkey RT73-firmware and when I plug the dongle, I've got in the syslog :
[kernel] rt73usb 1-1:1.0: firmware: requesting rt73.bin
[kernel] phy0 -> rt2x00usb_vendor_request: Error - Vendor Request 0x07 failed for offset 0x3040 with error -110.
Any ideas?
Regards
> Date: Wed, 7 Sep 2011 21:21:42 +0300
> From: pasik@xxxxxx
> To: bub_nimli@xxxxxxxxxxx
> CC: xen-users@xxxxxxxxxxxxxxxxxxx
> Subject: Re: [Xen-users] How to PVUSB with xen-sources-2.6.34-r4 and	xen-4.1.1 on gentoo
> 
> On Mon, Sep 05, 2011 at 09:48:07AM +0000, bub nimli wrote:
> >    Hello,
> > 
> >    I've installed xen-4.1.1 on with Gentoo xen-sources-2.6.34-r4 (both dom0
> >    and domU) on an AMD athlon XP 32 bits.
> >    I PCI passthrugh the whole USB-2.0 controler to the domU to gain access to
> >    my wifi dongle and everything works fine and stable.
> > 
> >    However, I've got an USB drive that I want to use on my dom0 wich requires
> >    USB-2.0 too and then cannot use anymore the PCI passthrugh method but the
> >    PVUSB method.
> > 
> >    Here is the problem, creating the virtual USB controler and attaching the
> >    dongle to this controler works and in domU lsusb shows both the controler
> >    and the dongle but as soon as I try to up the wlan device, dom0 crash.
> > 
> >    Does anybody have any succes with PVUSB on PV domUs and how?
> >    Any ideas on how I can make PVUSB work ?
> > 
> 
> http://wiki.xen.org/xenwiki/XenUSBPassthrough
> 
> -- Pasi
>