[Spice-devel] Questions on usbredir + XSpice

[Hans de Goede]

Hi,

On 08/06/2014 01:29 PM, Alon Levy wrote:
> On 08/06/2014 02:02 PM, Hans de Goede wrote:
>> Hi,
>>
>> On 08/06/2014 08:02 AM, Alon Levy wrote:
>>> On 08/05/2014 10:52 PM, Jeremy White wrote:
>>>> While I'm researching, I thought I'd look into the next challenge for
>>>> XSpice - usb device redirection.
>>>>
>>>> It faces similar challenges to the CAC card stuff.  That is, my sense is
>>>> that the usbredir library and utility set is all about reading client
>>>> machine USB device information and relaying it through to qemu, which
>>>> then exposes it as a 'real' device to the guest OS.
>>>>
>>>> Again, with XSpice, we don't have qemu :-(.
>>>>
>>>> Ideally, we'd find some mechanism to inject a usb device into the system
>>>> running XSpice.
>>>>
>>>> I've done some further research, and the usbip project would seem
>>>> useful.  It was here:
>>>>    http://usbip.sourceforge.net/
>>>> but apparently is now in the kernel.
>>>>
>>>> If we use that, then the challenge would appear to be translating the
>>>> protocols.
>>>>
>>>> Alternates:
>>>>   1.  Use usbip end-to-end
>>>>        I'd like to avoid this; there are benefits to having all spice
>>>> traffic go over the same channel
>>>>   2.  ???  Insight appreciated <grin> ???
>>>>       (I can't help but feel there are other methods for simulating a
>>>> USB device, but I'm fairly ignorant of this space).
>>>>
>>>
>>> 2. Teach usbredir to use a kernel without a vm.
>>
>> Yes that would be the rigt solution to this, there are use-cases outside
>> of Xspice for this too. The solution you're looking for here is to
>> wtite a virtual hcd device (driver) for the kernel talking the
> 
> So something like http://sourceforge.net/projects/usb-vhci/ ?

That sounds abour right (I did not take a look)

> Or if that is a bad starting point, which one is?
> ehci-hcd.c / ohci-hcd.c / other? (looking at kernel/drivers/usb/host)

The link you gave sounds right, and a better start then one of the existing
drivers for real hardware, but I did not actually look at it, sorry
-ENOTIME.

Regards,

Hans