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Re: [Xen-users] How to present the vusb device entry in the xenstore


Thank you very much for your reply. I will reply inline.

2013/6/18 Ian Campbell <Ian.Campbell@xxxxxxxxxx>
On Tue, 2013-06-18 at 08:51 +0800, Bei Guan wrote:
> Hi,
> I'd like to use the pvusb device in xen-4.3 unstable. However, when I
> use the command "xenstore-ls /local/domain/domId/device" in my VM,
> there's no "vusb" device presented.

Which toolstack are you using?

Which kind of guest (PV or HVM or PVHVM) is it? Which kernels are you
using in dom0 and domU?

I'm not sure which (emulated USB device passthrough or full PV USB) you
are referring to as "vusb".

I use the xl tools and the guest is FreeBSD (It's PVHVM). I think other PVHVM DomUs are also the same. The dom0 is linux 2.6.32-5-xen-amd64 or linux 3.9.1 x86_64 (both the same for me).
I just want to know how to make the USB frontend and backend drivers to work correctly for a PVHVM DomU. 
If the DomU uses the emulated USB devices presented by xen-qemu, the USB frontend and backend drivers will not work. And, the usb devices for DomU cannot be seen in the XenStore. Is it right?
It seem that I have never seen the usb device in DomU's XenStore entries, even for PV and HVM.

I'd like to add a PVUSB front driver for FreeBSD, so I need to make sure that the PVUSB device is added by DomU's XenBus driver and the PVUSB backed driver in Dom0 works well.
However, it seems that the PVHVM DomU always uses the USB hardware emulated by xen-qemu. So my PVUSB front driver cannot probe the PVUSB device.

AFAIK for xl in 4.3 only USB passthrough to HVM domains via device model
emulation of the host controller is supported.

Support for PVUSB is on the cards for 4.4 I think, although AIUI it is
somewhat blocked on someone stepping up and taking responsibility for
the PVUSB driver side of things.
Do you mean that before the Xen 4.4, there are no xen versions supporting the the PVUSB frontend and backend dirvers? 
If I want to use the PVUSB, I need to move on to Xen 4.4?


I have a vague feeling there is also conceptually a third type of USB
passthrough, but I can't quite remember what it consists of.

> Here, "0ea0:2168"is the ID of a 128M usb disk and got using the lsusb
> command.

In this case you could presumably instead export the corresponding
dom0 /dev/sdX node to the guest as a disk device.


Best Regards,
Bei Guan
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