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Re: [Xen-users] Status of USB in xl toolstack

On Tue, 2014-04-08 at 10:11 +0100, George Dunlap wrote:
> On 04/08/2014 09:31 AM, Ian Campbell wrote:
> > I don't know what George plans and you've dropped the CC so he is
> > unlikely to see the question. I've put it back and left the quotes
> > untrimmed.
> >
> > I don't believe you need to reboot the host to use PCI passthrough, in
> > most cases you can dynamically rebind. There are helpers in xl to do
> > this, or you can poke at sysfs directly.
> >
> > I think it would be unlikely that rebooting the host would be necessary
> > for USB passthrough.
> So there are several ways to get your USB device to your guest:
> 1. PCI pass-through of the host USB controller
> 2. passing through a host USB device via qemu emulation
> 3. passing through a host USB device via PVUSB
> #1 is available and pretty well understood.  It has never required 
> booting your host -- you could always dynamically assign a device to 
> pciback after you've booted.  Before 4.2 this required a bunch of manual 
> frobbing about in sysfs; since 4.2 there are some convenient xl commands 
> to do so.  See the wiki page here:
> http://wiki.xenproject.org/wiki/Xen_PCI_Passthrough
> In #2, qemu emulates the USB controller, but passes the USB commands 
> through to the host device.  This has been available as a static 
> configuration for a long time; as of at least 4.3 you could pass in 
> arbitrary numbers of devices.  Depending on your USB device, if you do 
> #2 you may need to set the "usbversion" in your config file as well.
> There is no way to do USB "hot-plug" for this mode yet -- I have a patch 
> series that's functional, but still needs to be tweaked to get the 
> interface right.
> In #3, usbback passes the USB commands through to the host device.  This 
> requires pcifront in your guest and pciback in your domU and dom0 

ITYM usbfront and usbback here.

> respectively.  There is no xl support for this yet, but as with pci 
> pass-through, there are ways you can make this happen manually by 
> frobbing about with xenstore.
> Hopefully that gives you some options.
>   -George

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