Re: [Xen-devel] [PATCH 2/3] xen/kbdif: Add unique input device identifier

[Oleksandr Andrushchenko <andr2000@xxxxxxxxx>]

On 06/07/2018 06:47 PM, Konrad Rzeszutek Wilk wrote:
> On Thu, Jun 07, 2018 at 04:40:48PM +0300, Oleksandr Andrushchenko wrote:
> > On 06/07/2018 04:28 PM, Konrad Rzeszutek Wilk wrote:
> > > On Wed, May 23, 2018 at 09:19:22AM +0300, Oleksandr Andrushchenko wrote:
> > > > From: Oleksandr Andrushchenko <oleksandr_andrushchenko@xxxxxxxx>
> > > >
> > > > If frontend is configured to expose multiple input device instances
> > > > then backend may require a way to uniquely identify concrete input
> > > > device within the frontend. This is useful for use-cases where
> > > > virtual input device needs to be matched to physical input device.
> > > > Add XenBus "unique-id" node parameter, so this sort of use-cases can
> > > > be implemented.
> > > >
> > > > Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@xxxxxxxx>
> > > > ---
> > > >    xen/include/public/io/kbdif.h | 10 ++++++++++
> > > >    1 file changed, 10 insertions(+)
> > > >
> > > > diff --git a/xen/include/public/io/kbdif.h b/xen/include/public/io/kbdif.h
> > > > index a68da0f1a37f..45e4ff5b0a05 100644
> > > > --- a/xen/include/public/io/kbdif.h
> > > > +++ b/xen/include/public/io/kbdif.h
> > > > @@ -82,6 +82,15 @@
> > > >     *      for pointer devices should set this to 1. Raw (unscaled) values have
> > > >     *      a range of [0, 0x7fff].
> > > >     *
> > > > + *-----------------------  Device Instance Parameters ------------------------
> > > > + *
> > > > + * unique-id
> > > > + *      Values:         <uint32_t>
> > > Wouldn't a string be easier? That way you can extend this in the future
> > > to also have an UUID or so?
> > Much easier. We were thinking about that as well, but sndif already has it
> > as uint32_t. If you are ok to change uniquie-id for sndif to string then
> > that
> > would be much better: UUID as you mention + all protocols have unique-id
> > consistently defined as string.
> > sndif's unique-id is not used by the frontend driver and we are about
> > to start libx/xl support for sound, so I think this is the right time for
> > such a change.
> > If you are fine with that then I'll send yet another patch for sndif.
> Please do and feel free to add
>
> Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
>
> on it.
>
> Also pls CC Juergen so he can release-ack it.
Thank you
> > > > + *
> > > > + *      After device instance initialization it is assigned a unique ID
> > > > + *      (within the front driver), so every instance of the frontend can be
> > > > + *      identified by the backend by this ID.
> > > > + *
> > > >     *------------------------- Pointer Device Parameters 
> > > > ------------------------
> > > >     *
> > > >     * width
> > > > @@ -204,6 +213,7 @@
> > > >    #define XENKBD_FIELD_MT_WIDTH          "multi-touch-width"
> > > >    #define XENKBD_FIELD_MT_HEIGHT         "multi-touch-height"
> > > >    #define XENKBD_FIELD_MT_NUM_CONTACTS   "multi-touch-num-contacts"
> > > > +#define XENKBD_FIELD_UNIQUE_ID         "unique-id"
> > > >    /* OBSOLETE, not recommended for use */
> > > >    #define XENKBD_FIELD_RING_REF          "page-ref"
> > > > --
> > > > 2.17.0

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