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

[George Dunlap <George.Dunlap@xxxxxxxxxxxxx>]

On Wed, May 20, 2015 at 3:33 PM, Juergen Gross <jgross@xxxxxxxx> wrote:
> On 05/20/2015 04:20 PM, George Dunlap wrote:
>>
>> On Mon, Apr 20, 2015 at 9:12 AM, Juergen Gross <jgross@xxxxxxxx> wrote:
>>>
>>> On 04/19/2015 05:50 AM, Chunyan Liu wrote:
>>>>
>>>>
>>>> Add pvusb commands: usb-ctrl-attach, usb-ctrl-detach, usb-list,
>>>> usb-attach and usb-detach.
>>>>
>>>> To attach a usb device to guest through pvusb, one could follow
>>>> following example:
>>>>
>>>>    #xl usb-ctrl-attach test_vm version=1 num_ports=8
>>>>
>>>>    #xl usb-list test_vm
>>>>    will show the usb controllers and port usage under the domain.
>>>>
>>>>    #xl usb-attach test_vm 1.6
>>>>    will find the first usable controller:port, and attach usb
>>>>    device whose bus address is 1.6 (busnum is 1, devnum is 6)
>>>>    to it. One could also specify which <controller> and which <port>.
>>>>
>>>>    #xl usb-detach test_vm 1.6
>>>>
>>>>    #xl usb-ctrl-detach test_vm dev_id
>>>>    will destroy the controller with specified dev_id. Dev_id
>>>>    can be traced in usb-list info.
>>>>
>>>> Signed-off-by: Chunyan Liu <cyliu@xxxxxxxx>
>>>> Signed-off-by: Simon Cao <caobosimon@xxxxxxxxx>
>>>> ---
>>>> Changes to v2:
>>>>     * use bus.addr as user interface instead of busid in
>>>> usb-attach|detach
>>>>     * remove usb-assignable-list interface
>>>
>>>
>>>
>>> Why? While lsusb in combination with xl usb-list for each domain will
>>> give the same information, having to iterate through all domains can be
>>> quite annoying.
>>>
>>> An alternative would be to accept omitting the domain for xl usb-list
>>> and list all domains with assigned usb devices in this case.
>>
>>
>> I don't understand what information it is that you want.  Do you want
>> a list of devices *not already assigned* to domains?
>
>
> Yes.

...and why do you need that, instead of just remembering what you'd
assigned to whom?

We don't really have the equivalent for pci either.  That is, if a
device shows up in "lspci" but not in "pci-assignable-list", that may
be either because 1) I hasn't yet been assigned to pciback (and this
is available to be assigned to a domain), or 2) because it's already
been assigned to a domain.  Someone new coming to the system would
need to check all VMs to see which devices hadn't yet been assigned.

 -George

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