Re: [Qemu-devel] [PATCH 0/3] add usb_detach and usb_attach (v3)

[Alon Levy]

On Thu, Oct 21, 2010 at 08:13:19AM -0500, Anthony Liguori wrote:
> On 10/21/2010 08:03 AM, Gerd Hoffmann wrote:
> >On 10/21/10 08:36, Alon Levy wrote:
> >>v2->v3 changes:
> >>  * add configure parameter
> >>  * fix docs
> >>
> >>v2 message:
> >>This patchset uses id like device_del for attaching/detaching usb
> >>devices. The first two patches ready the way:
> >>  1. makes qdev_find_recursive non static and in qdev.h
> >>  2. adds a usb_device_by_id which goes over the usb buses calling
> >>   qdev_find_recursive
> >>  3. adds the commands that use usb_device_by_id
> >>
> >>Alon Levy (3):
> >>   qdev: make qdev_find_recursive public
> >>   usb: add public usb_device_by_id
> >>   monitor: add usb_attach and usb_detach (v2)
> >>
> >
> >Acked-by: Gerd Hoffmann <address@hidden>
> 
> Okay, I am still confused about the use-case for this and I don't
> see any further explanation in the commit messages.  I've seen
> "debugging" but can you be a bit more specific about which cases
> it's needed for?

To elaborate a little more, when using a certificates based card
there is no hardware event (i.e. removing/inserting the physical card)
that causes a usb_detach/attach to the card (both in passthru and
emulated), but otoh certificates is good for testing since it decouples
it from NSS/tcp. So I needed some way to emulate an insert/remove, and
I saw usb_del, which was pretty close, and voila. This is not the same
as card remove/reinsert, but it is exactly what will happen to the
guest when spicec connects/disconnects, since I detach devices on
disconnect and attach on connect.

> 
> This is just adding a HMP command.  Is that the right approach or
> was that an unintentional consequence of rebasing post-HMP/QMP
> split?
> 
> Regards,
> 
> Anthony Liguori
> 
> >
> >cheers,
> >  Gerd
> >
> >
> 
>