Advertise "feature-vkbd-standalone" to indicate the backend
can connect without a vfb device connection.
When "request-vkbd-standalone" is set to 1, the backend does
not wait for a QemuConsole to be setup before connecting the 
vkbd device. This also means that absolute coordinates cannot
be scaled to the non-existent QemuConsole's sizes, and remain
unscaled, in the range [0, 0x7FFF].

Signed-off-by: Owen Smith <owen.smith@citrix.com>
---
 hw/display/xenfb.c | 32 ++++++++++++++++++++++----------
 1 file changed, 22 insertions(+), 10 deletions(-)

diff --git a/hw/display/xenfb.c b/hw/display/xenfb.c
index e76c0d8..2ebc81b 100644
--- a/hw/display/xenfb.c
+++ b/hw/display/xenfb.c
@@ -52,6 +52,7 @@ struct common {
 struct XenInput {
     struct common c;
     int abs_pointer_wanted; /* Whether guest supports absolute pointer */
+    int vkbd_standalone;    /* Guest supports vkbd without vfb device */
     int button_state;       /* Last seen pointer button state */
     int extended;
     QEMUPutMouseEntry *qmouse;
@@ -306,18 +307,22 @@ 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;
+    int i, x, y;
+    if (xenfb->c.con != NULL) {
+        DisplaySurface *surface = qemu_console_surface(xenfb->c.con);
+        int dw = surface_width(surface);
+        int dh = surface_height(surface);
+        x = dx * (dh - 1) / 0x7fff;
+        y = dy * (dw - 1) / 0x7fff;
+    } else {
+        x = dx;
+        y = dy;
+    }
 
     trace_xenfb_mouse_event(opaque, dx, dy, dz, button_state,
                             xenfb->abs_pointer_wanted);
     if (xenfb->abs_pointer_wanted)
-	xenfb_send_position(xenfb,
-			    dx * (dw - 1) / 0x7fff,
-			    dy * (dh - 1) / 0x7fff,
-			    dz);
+        xenfb_send_position(xenfb, x, y, dz);
     else
 	xenfb_send_motion(xenfb, dx, dy, dz);
 
@@ -336,6 +341,7 @@ 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-vkbd-standalone", 1);
     return 0;
 }
 
@@ -345,8 +351,14 @@ static int input_initialise(struct XenDevice *xendev)
     int rc;
 
     if (!in->c.con) {
-        xen_pv_printf(xendev, 1, "ds not set (yet)\n");
-        return -1;
+        if (xenstore_read_fe_int(xendev, "request-vkbd-standalone",
+                                 &in->vkbd_standalone) == -1) {
+            in->vkbd_standalone = 0;
+        }
+        if (in->vkbd_standalone == 0) {
+            xen_pv_printf(xendev, 1, "ds not set (yet)\n");
+            return -1;
+        }
     }
 
     rc = common_bind(&in->c);
-- 
2.1.4

On Thu, 8 Jun 2017, Owen Smith wrote:
> Advertise "feature-vkbd-standalone" to indicate the backend
> can connect without a vfb device connection.
> When "request-vkbd-standalone" is set to 1, the backend does
> not wait for a QemuConsole to be setup before connecting the 
> vkbd device. This also means that absolute coordinates cannot
> be scaled to the non-existent QemuConsole's sizes, and remain
> unscaled, in the range [0, 0x7FFF].
> 
> Signed-off-by: Owen Smith <owen.smith@citrix.com>
> ---
>  hw/display/xenfb.c | 32 ++++++++++++++++++++++----------
>  1 file changed, 22 insertions(+), 10 deletions(-)
> 
> diff --git a/hw/display/xenfb.c b/hw/display/xenfb.c
> index e76c0d8..2ebc81b 100644
> --- a/hw/display/xenfb.c
> +++ b/hw/display/xenfb.c
> @@ -52,6 +52,7 @@ struct common {
>  struct XenInput {
>      struct common c;
>      int abs_pointer_wanted; /* Whether guest supports absolute pointer */
> +    int vkbd_standalone;    /* Guest supports vkbd without vfb device */
>      int button_state;       /* Last seen pointer button state */
>      int extended;
>      QEMUPutMouseEntry *qmouse;
> @@ -306,18 +307,22 @@ 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;
> +    int i, x, y;
> +    if (xenfb->c.con != NULL) {
> +        DisplaySurface *surface = qemu_console_surface(xenfb->c.con);
> +        int dw = surface_width(surface);
> +        int dh = surface_height(surface);
> +        x = dx * (dh - 1) / 0x7fff;
> +        y = dy * (dw - 1) / 0x7fff;
> +    } else {
> +        x = dx;
> +        y = dy;
> +    }
>  
>      trace_xenfb_mouse_event(opaque, dx, dy, dz, button_state,
>                              xenfb->abs_pointer_wanted);
>      if (xenfb->abs_pointer_wanted)
> -	xenfb_send_position(xenfb,
> -			    dx * (dw - 1) / 0x7fff,
> -			    dy * (dh - 1) / 0x7fff,
> -			    dz);
> +        xenfb_send_position(xenfb, x, y, dz);
>      else
>  	xenfb_send_motion(xenfb, dx, dy, dz);
>  
> @@ -336,6 +341,7 @@ 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-vkbd-standalone", 1);
>      return 0;
>  }
>  
> @@ -345,8 +351,14 @@ static int input_initialise(struct XenDevice *xendev)
>      int rc;
>  
>      if (!in->c.con) {
> -        xen_pv_printf(xendev, 1, "ds not set (yet)\n");
> -        return -1;
> +        if (xenstore_read_fe_int(xendev, "request-vkbd-standalone",
> +                                 &in->vkbd_standalone) == -1) {
> +            in->vkbd_standalone = 0;
> +        }
> +        if (in->vkbd_standalone == 0) {
> +            xen_pv_printf(xendev, 1, "ds not set (yet)\n");
> +            return -1;
> +        }

In your changes to include/public/io/kbdif.h, make sure to write when
(at what xenstore status stage) the frontend needs to write
request-vkbd-standalone. 

This patch looks good:

Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>



>      }
>  
>      rc = common_bind(&in->c);