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

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Wed, May 23, 2018 at 09:19:22AM +0300, Oleksandr Andrushchenko wrote:
> From: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
> 
> 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@epam.com>
> ---
>  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?

> + *
> + *      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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