Re: [Xen-devel] [PATCH 3/3] xenfb: Add "feature-no-abs-rescale" for Windows PV frontend

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Wed, 10 Sep 2014, Owen smith wrote:
> Windows PV frontend requires absolute mouse values in the range
> [0, 0x7fff]. Add a feature to not rescale the axes to DisplaySurface
> size. Also allows Windows PV frontend to connect without a vfb
> device. Moves the rescaling of axes to a seperate function with
> additional null-pointer checks.
> 
> Signed-off-by: Owen smith <owen.smith@xxxxxxxxxx>
> ---
>  hw/display/xenfb.c | 52 +++++++++++++++++++++++++++++++++++++---------------
>  1 file changed, 37 insertions(+), 15 deletions(-)
> 
> diff --git a/hw/display/xenfb.c b/hw/display/xenfb.c
> index c4375c8..65c373b 100644
> --- a/hw/display/xenfb.c
> +++ b/hw/display/xenfb.c
> @@ -61,6 +61,7 @@ struct common {
>  struct XenInput {
>      struct common c;
>      int abs_pointer_wanted; /* Whether guest supports absolute pointer */
> +    int no_abs_rescale;     /* Whether guest wants rescaled abs axes */
>      int button_state;       /* Last seen pointer button state */
>      int extended;
>      QEMUPutKbdEntry *qkbd;
> @@ -325,6 +326,25 @@ static void xenfb_key_event(void *opaque, int scancode)
>      xenfb_send_key(xenfb, down, scancode2linux[scancode]);
>  }
>  
> +static void xenfb_rescale_mouse(struct XenInput *xenfb, int *dx, int *dy)
> +{
> +    DisplaySurface *surface;
> +    int dw, dh;
> +
> +    if (xenfb->c.con == NULL) {
> +        return;
> +    }
> +    surface = qemu_console_surface(xenfb->c.con);
> +    if (surface == NULL) {
> +        return;
> +    }
> +    dw = surface_width(surface);
> +    dh = surface_height(surface);
> +
> +    *dx = *dx * (dw - 1) / 0x7fff;
> +    *dy = *dy * (dh - 1) / 0x7fff;
> +}
> +
>  /*
>   * Send a mouse event from the client to the guest OS
>   *
> @@ -338,18 +358,16 @@ static void xenfb_mouse_event(void *opaque,
>                             int dx, int dy, int dz, int button_state)
>  {
>      struct XenInput *xenfb = opaque;
> -    DisplaySurface *surface = qemu_console_surface(xenfb->c.con);
> -    int dw = surface_width(surface);
> -    int dh = surface_height(surface);
>      int i;
>  
> -    if (xenfb->abs_pointer_wanted)
> -     xenfb_send_position(xenfb,
> -                         dx * (dw - 1) / 0x7fff,
> -                         dy * (dh - 1) / 0x7fff,
> -                         dz);
> -    else
> +    if (xenfb->abs_pointer_wanted) {
> +        if (!xenfb->no_abs_rescale) {
> +            xenfb_rescale_mouse(xenfb, &dx, &dy);
> +        }
> +        xenfb_send_position(xenfb, dx, dy, dz);
> +    } else {
>       xenfb_send_motion(xenfb, dx, dy, dz);
> +    }
>  
>      for (i = 0 ; i < 8 ; i++) {
>       int lastDown = xenfb->button_state & (1 << i);
> @@ -366,6 +382,7 @@ static void xenfb_mouse_event(void *opaque,
>  static int input_init(struct XenDevice *xendev)
>  {
>      xenstore_write_be_int(xendev, "feature-abs-pointer", 1);
> +    xenstore_write_be_int(xendev, "feature-no-abs-rescale", 1);
>      return 0;
>  }
>  
> @@ -374,7 +391,17 @@ static int input_initialise(struct XenDevice *xendev)
>      struct XenInput *in = container_of(xendev, struct XenInput, c.xendev);
>      int rc;
>  
> -    if (!in->c.con) {
> +    if (xenstore_read_fe_int(xendev, "request-abs-pointer",
> +                             &in->abs_pointer_wanted) == -1) {
> +        in->abs_pointer_wanted = 0;
> +    }
> +
> +    if (xenstore_read_fe_int(xendev, "request-no-abs-rescale",
> +                             &in->no_abs_rescale) == -1) {
> +        in->no_abs_rescale = 0;
> +    }

I don't think is safe to move checking for "request-abs-pointer" so
early: what if the guest writes request-abs-pointer after initialise but
before connect?

Also it would be nice to document this protocol extension somewhere. I
do realize that the existing documentation on vfb is somewhat lacking.


> +    if (!in->c.con && !in->no_abs_rescale) {

Why this change?


>          xen_be_printf(xendev, 1, "ds not set (yet)\n");
>          return -1;
>      }
> @@ -390,11 +417,6 @@ static void input_connected(struct XenDevice *xendev)
>  {
>      struct XenInput *in = container_of(xendev, struct XenInput, c.xendev);
>  
> -    if (xenstore_read_fe_int(xendev, "request-abs-pointer",
> -                             &in->abs_pointer_wanted) == -1) {
> -        in->abs_pointer_wanted = 0;
> -    }
> -
>      if (in->qmouse) {
>          qemu_remove_mouse_event_handler(in->qmouse);
>      }
> -- 
> 2.1.0
> 

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel