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

[Ryan Harper <ryanh@us.ibm.com>]

* Alon Levy <alevy@redhat.com> [2010-10-21 08:26]:
> 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 <kraxel@redhat.com>
> > 
> > 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?
> > 
> 
> I use it for debugging the usb-ccid device. I think it's useful for
> any other usb device tests as well. The existing commands are not
> good enough to do a remove/insert of a usb device, since deleting
> a device also deletes any chardev associated with it, and there is
> no monitor command to add a chardev. Also sometimes you don't want
> to close the chardev, just have the guest see a removal/reinsert of
> the device.
> 
> > This is just adding a HMP command.  Is that the right approach or
> > was that an unintentional consequence of rebasing post-HMP/QMP
> > split?
> > 
> 
> yes, my bad, I have not used qmp before, I can add the code but no
> idea how to test it easily.

just walked through this one myself; you can update the qmp-command.hx
to refer to the same handler (assuming your handler parses qdict etc).

Then to test the QMP interface, I read qemu/QMP/README and ended up
using a qmp config file and -reconfig, and then qemu/QMP/qmp-shell
Which gives you a HMP like monitor interface where you can execute QMP
commands.


-- 
Ryan Harper
Software Engineer; Linux Technology Center
IBM Corp., Austin, Tx
ryanh@us.ibm.com