Re: [PATCH V3 4/6] xl: add pvusb commands

[George Dunlap <george.dunlap@eu.citrix.com>]

On 05/21/2015 02:55 PM, Juergen Gross wrote:
> On 05/21/2015 03:43 PM, George Dunlap wrote:
>> On 05/21/2015 02:08 PM, Juergen Gross wrote:
>>> On 05/21/2015 03:01 PM, George Dunlap wrote:
>>>> On 05/21/2015 12:58 PM, Juergen Gross wrote:
>>>>> There might be existing users who know about "xm usb-assignable-list".
>>>>
>>>> Yes -- unfortunately something has to give: either we confuse new users
>>>> with two names that sound similar but do something different, or we
>>>> confuse former xm users by renaming their function, or we confuse
>>>> current xl users by renaming their function.  There's badness to be had
>>>> whichever one we choose.  I think renaming the xm function is the least
>>>> bad of all the options.
>>>>
>>>>> OTOH I don't care giving it another name, as long as the functionality
>>>>> is available.
>>>>
>>>> OK -- what about "usb-available-list"?  Any objections / alternate
>>>> suggestions from anyone?
>>>
>>> Hmm, just another idea:
>>>
>>> xl usb-list -a
>>>
>>> could list all domains with assigned USB-devices and the currently not
>>> assigned devices as well. This would avoid the need for another command
>>> name. It would even be possible to omit the "-a".
>>
>> That works for me too, I guess.
>>
>> Can I suggest, though, that work on that functionality be detached from
>> getting the core pvusb functionality in?  I can't really effectively do
>> the qemu side until it is in due to the cost of rebasing, and I would
>> really like to have both in for 4.6 if possible.
> 
> Sure.
> 
> I hope to have my pvusb backend in qemu ready until then, too. :-)
> In case the performance isn't too bad I'll have to make some changes to
> the libxl part as well, but this will result in some deletions only
> (qemu will do driver unbinding, this will no longer be required to be
> done by libxl).

Right -- just like it's not necessary when qemu does emulated device
passthrough. :-)

Out of curiosity, what's the motivation for doing pvusb in qemu?  Will
there be an option, for instance, to switch usb devices from emulated
over to pv when the magic port is written to (as is done with disks &
network currently)?

 -George