Re: [Xen-devel] [PATCH] fbfront: advertise either absolute or relative coordinates

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Thu, 10 Mar 2011, Olaf Hering wrote:
> A virtualized display device is usually viewed with the vncviewer
> application, either by 'xm vnc domU' or with vncviewer localhost:port.
> vncviewer and the RFB protocol provides absolute coordinates to the
> virtual display. These coordinates are either passed through to a PV
> guest or converted to relative coordinates for a HVM guest.
> 
> A PV guest receives these coordinates and passes them to the kernels
> evdev driver. There it can be picked up by applications such as the
> xorg-input drivers. Using absolute coordinates avoids issues such as
> guest mouse pointer not tracking host mouse pointer due to wrong mouse
> acceleration settings in the guests X display.
> 
> Advertise either absolute or relative coordinates to the input system
> and the evdev driver, depending on what dom0 provides. The xorg-input
> driver prefers relative coordinates even if a devices provides both.
> 
> Signed-off-by: Olaf Hering <olaf@xxxxxxxxx>
> 
> ---
>  drivers/xen/fbfront/xenkbd.c |   28 ++++++++++++++--------------
>  1 file changed, 14 insertions(+), 14 deletions(-)
> 
> Index: linux-2.6.18-xen.hg/drivers/xen/fbfront/xenkbd.c
> ===================================================================
> --- linux-2.6.18-xen.hg.orig/drivers/xen/fbfront/xenkbd.c
> +++ linux-2.6.18-xen.hg/drivers/xen/fbfront/xenkbd.c
> @@ -104,7 +104,7 @@ static irqreturn_t input_handler(int rq,
>  int __devinit xenkbd_probe(struct xenbus_device *dev,
>                          const struct xenbus_device_id *id)
>  {
> -     int ret, i;
> +     int ret, i, abs;
>       struct xenkbd_info *info;
>       struct input_dev *kbd, *ptr;
>  
> @@ -123,6 +123,11 @@ int __devinit xenkbd_probe(struct xenbus
>       info->page->in_cons = info->page->in_prod = 0;
>       info->page->out_cons = info->page->out_prod = 0;
>  
> +     if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-abs-pointer", "%d", 
> &abs) < 0)
> +             abs = 0;
> +     if (abs)
> +             xenbus_printf(XBT_NIL, dev->nodename, "request-abs-pointer", 
> "1");
> +
>       /* keyboard */
>       kbd = input_allocate_device();
>       if (!kbd)
> @@ -155,10 +160,15 @@ int __devinit xenkbd_probe(struct xenbus
>       ptr->id.bustype = BUS_PCI;
>       ptr->id.vendor = 0x5853;
>       ptr->id.product = 0xfffe;
> -     ptr->evbit[0] = BIT(EV_KEY) | BIT(EV_REL) | BIT(EV_ABS);
> +     ptr->evbit[0] = BIT(EV_KEY);
> +     if (abs)
> +             ptr->evbit[0] |= BIT(EV_ABS);
> +     else {
> +             ptr->evbit[0] |= BIT(EV_REL);
> +             ptr->relbit[0] = BIT(REL_X) | BIT(REL_Y) | BIT(REL_WHEEL);
> +     }
>       for (i = BTN_LEFT; i <= BTN_TASK; i++)
>               set_bit(i, ptr->keybit);
> -     ptr->relbit[0] = BIT(REL_X) | BIT(REL_Y) | BIT(REL_WHEEL);
>       input_set_abs_params(ptr, ABS_X, 0, XENFB_WIDTH, 0, 0);
>       input_set_abs_params(ptr, ABS_Y, 0, XENFB_HEIGHT, 0, 0);
>  

does this mean that we are not getting any wheel events when we are
using absolute coordinates?


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