Re: [Xen-devel] USB passthrough with Xen on ARM

[Roger Quadros <rogerq@xxxxxx>]


Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. 
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki

On 12/09/17 13:57, Julien Grall wrote:
> Hi,
> 
> On 12/09/17 11:00, Juergen Gross wrote:
>> On 12/09/17 10:13, Roger Quadros wrote:
>>> Hi,
>>>
>>> I'm running Xen v4.9 on DRA7 (OMAP5/ArmV7) with Linux kernel v3.14 
>>> (yikes!!) on dom0 and domU.
>>> I'm struggling to get USB passthrough working using pvUSB.
>>>
>>> My domU config file contains
>>>     usb = 1
>>>     usbctrl = ['type=qusb,version=2,ports=4', 'type=qusb,version=1, 
>>> ports=4', ]
>>>
>>> I can see the vusb-0 and vusb-1 platform devices in /sys/devices
>>>
>>> And the following message on domU kernel log
>>> [    1.849572] xenbus_probe_frontend: Device with no driver: device/vusb/0
>>> [    1.849627] xenbus_probe_frontend: Device with no driver: device/vusb/1
>>>
>>> This means that there is no device driver for the vusb host controllers.
>>>
>>> What is the way forward? Do I need to apply some patches to the domU kernel 
>>> to
>>> add support for the USB frontend HCD drivers?
>>
>> This is one mandatory step, yes. You'll need:
>>
>> https://lkml.org/lkml/2015/6/23/34
>> https://lkml.org/lkml/2015/6/23/36
>>

OK, after applying the above 2 patches to v4.12 kernel for domU I'm able to see 
the xen HCD driver
enumerate, but it times out most likely due to the missing pvusb backend.

[    0.510149] vusb vusb-0: Xen USB2.0 Virtual Host Controller
[    0.510192] vusb vusb-0: new USB bus registered, assigned bus number 1
[    0.510811] hub 1-0:1.0: USB hub found
[    0.510865] hub 1-0:1.0: 4 ports detected
[    0.812721] vusb vusb-1: Xen USB1.1 Virtual Host Controller
[    0.812760] vusb vusb-1: new USB bus registered, assigned bus number 2
[    0.813356] hub 2-0:1.0: USB hub found
[    0.813410] hub 2-0:1.0: 4 ports detected

...

[    5.888997] xenbus_probe_frontend: Waiting for devices to initialise: 
25s...20s...15s...10s...5s...0s...
[   35.919000] 
235s...230s...225s...220s...215s...210s...205s...200s...195s...190s...185s...180s...175s...170s...165s...160s...155s...150s...145s...140s...135s...130s...125s...120s...115s...110s...105s...100s...95s...90s...85s...80s...75s...70s...65s...60s...55s...50s...45s...40s...35s...30s...25s...20s...15s...10s...5s...0s...
[  270.879130] 
[  270.884161] xenbus_probe_frontend: Timeout connecting to device: 
device/vusb/0 (local state 1, remote state 1)
[  270.887059] xenbus_probe_frontend: Timeout connecting to device: 
device/vusb/1 (local state 1, remote state 1)

>> The question is whether this will be enough for you to make it work: the
>> pvusb backend is qemu based. I'm not sure this will just work on ARM.
> 
> Backends in QEMU should just work with ARM. Although, I haven't tried the 
> PVUSB one.
> 

Newbie question now. How do I start the QEMU pvusb backend on dom0?

-- 
cheers,
-roger


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