Re: [Libusb-devel] USB timeout from virtualbox guest

[Peter S. <pe...@st...>]

Hi!

Akos Vandra wrote:
> I've posted this question onto the virtualbox forums, but I'll try
> my luck here, maybe somebody had the same issue before.
> 
> I am running an Ubuntu x86(12.04b) Guest inside an Ubuntu 64 bit Host
> (10.04). Virtualbox version 4.1.12.r77245
> I am trying to communicate with a proprietary (but no secrets here)
> device using libusb.

You're not giving so many details. The properties of the device, in
particular if the device is low, full or high speed, and the
characteristics of your transfers are quite significant.


> Problem is the code is working fine within the Host, but when run from
> the Guest it keeps giving timeouts most of the time (but some requests
> complete just fine. About ~5-10%).
> Peeking with wireshark on the host shows that all usb bus transfers
> complete successfully, but peeking from the guest shows transfers
> which do not complete.

Please use

http://people.redhat.com/zaitcev/linux/usbmon-6.tar.gz

on both the host and the guest and post logs for analysis.


> It is as if the usb subsystem from the host does not forward some of
> the requests to the guest.

I hear that vbox simply does not work well for high speed. The EHCI
is not very easy to simply emulate, so I can understand it.


> Also interesting thing is that listing usb devices from the host
> also lists the device which should be claimed by the guest...

A USB device can not really be hidden from the host. Either the USB
stack is running on the host or it is not.


> Can you help me find out what could be happening, and how could I
> fix the problem?

See above. Maybe vbox supports PCI passthrough, then you can try that
for the EHCI, but that also means that no USB devices will be
available in the host. I don't know if this is acceptable for you.


//Peter