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

[Tim R. <ti...@pr...>]

Akos Vandra wrote:
> 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.
> 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%).

USB within a VM has always been a tricky proposition.  Anything with
timing restrictions or bandwidth stress is always going to be a
problem.  Remember that, even though a device is "claimed" by a guest,
that's all done with smoke and mirrors.  The host controller is being
entirely driven from the host, and interrupts are being delivered to the
host.  There are additional layers to route requests from "claimed"
devices to the guest systems, but that takes time.

Are you timeouts tight?

-- 
Tim Roberts, ti...@pr...
Providenza & Boekelheide, Inc.