Re: [Qemu-devel] USB Asynchronous I/O

[Salil Bijur]

On Nov 15, 2007 5:46 PM, Arnon Gilboa <address@hidden> wrote:
> I believe you can do it similar to the way I did for isochronous
> transfers in usb-linux.c.
> Remember that using SUBMITURB and REAPURBNDELAY ioctls, you need to add
> another signal and signal handler for the async bulk, and there might be
> some issues in the ohci/uhci because they currently assume only
> isochronous transfers are async. A minute ago I tried to implement the
> bulk transfers using SUBMITURB and REAPURB (which blocks until response)
> but it seems to hang qemu upon connecting a disk-on-key.
>

What about interrupt packets? For a bluetooth device, the interrupt
packets are sent almost every 2-3 ms. taking up most of the bandwidth.
These in turn called the synchronous ioctls hanging qemu for that
time. Making these asynchronous gives a timeout in the kernel's usb
subsystem.