Re: [PATCH V7 6/7] xl: add usb-assignable-list command

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

On 25/09/15 03:11, Chunyan Liu wrote:
> Add xl usb-assignable-list command to list assignable USB devices.
> Assignable USB device means the USB device type is assignable and
> it's not assigned to any guest yet.
> 
> Signed-off-by: Chunyan Liu <cyliu@suse.com>
> 
> ---
>   Same as "libxl: add libxl_device_usb_assignable_list API" patch,
>   this patch could be sqaushed to previous one. Split because of
>   some dispute. Could be squashed if acceptable, otherwise could
>   be removed.

I think it's worth pointing out to other reviewers that the
"usb-assignable-list" command introduced here:
1. Has identical behavior to "xm usb-assignable-list", but
2. Has different behavior than "xl pci-assignable-list".

Namely:

xl pci-assignable-list will list PCI devices which have been detached
from their normal driver and have been assigned to pciback (in
preparation for being attached to a domain).

This command will list all USB devices in dom0 that are not assigned to VMs.

Juergen and I had a long back-and-forth about it around v3.  I thought
having slightly different semantics might be confusing, and Juergen
thought the functionality was important to include.  We didn't really
come to a conclusion and none of the tools maintainers expressed an opinion.

I don't feel like arguing about it anymore, so I won't oppose the
naming; but I think whoever gives final approval should at least be
aware of the slight functional difference between {pci,usb}-assignable-list.

Other than that, the patch looks good to me.

 -George