diff -r 61c96456a3e1 drivers/xen/fbfront/xenfb.c
--- a/drivers/xen/fbfront/xenfb.c	Thu Dec 20 16:58:14 2007 +0000
+++ b/drivers/xen/fbfront/xenfb.c	Sat Jan 05 11:08:03 2008 -0700
@@ -62,6 +62,9 @@ struct xenfb_info
 	struct xenfb_page	*page;
 	unsigned long 		*mfns;
 	int			update_wanted; /* XENFB_TYPE_UPDATE wanted */
+	int			feature_resize; /* Backend has resize feature */
+	int			resize_dpy;
+	int			xres, yres;
 
 	struct xenbus_device	*xbdev;
 };
@@ -130,13 +133,17 @@ struct xenfb_info
  * Oh well, we wont be updating the writes to this page anytime soon.
  */
 
+#define XENFB_PIXCLOCK  9025  /* Xorg "1280x1024" 110.80 to FB 1000000/110.80 */ 
+#define XENFB_SCAN_LINE_LEN 1280
+#define XENFB_FRAME_BUFFER_LEN (1024 * 5120) // 5 MB framebuffer
 static int xenfb_fps = 20;
-static unsigned long xenfb_mem_len = XENFB_WIDTH * XENFB_HEIGHT * XENFB_DEPTH / 8;
+static unsigned long xenfb_mem_len = XENFB_FRAME_BUFFER_LEN;
 
 static int xenfb_remove(struct xenbus_device *);
 static void xenfb_init_shared_page(struct xenfb_info *);
 static int xenfb_connect_backend(struct xenbus_device *, struct xenfb_info *);
 static void xenfb_disconnect_backend(struct xenfb_info *);
+static void xenfb_refresh(struct xenfb_info *info, int x1, int y1, int w, int h);
 
 static void xenfb_do_update(struct xenfb_info *info,
 			    int x, int y, int w, int h)
@@ -155,6 +162,25 @@ static void xenfb_do_update(struct xenfb
 	mb();			/* ensure ring space available */
 	XENFB_OUT_RING_REF(info->page, prod) = event;
 	wmb();			/* ensure ring contents visible */
+	info->page->out_prod = prod + 1;
+
+	notify_remote_via_irq(info->irq);
+}
+
+static void xenfb_do_resize(struct xenfb_info *info)
+{
+	union xenfb_out_event event;
+	__u32 prod;
+
+	event.type = XENFB_TYPE_RESIZE;
+	event.resize.width = info->xres;
+	event.resize.height = info->yres;
+
+	prod = info->page->out_prod;
+	/* caller ensures !xenfb_queue_full() */
+	mb();           /* ensure ring space available */
+	XENFB_OUT_RING_REF(info->page, prod) = event;
+	wmb();          /* ensure ring contents visible */
 	info->page->out_prod = prod + 1;
 
 	notify_remote_via_irq(info->irq);
@@ -209,6 +235,16 @@ static void xenfb_update_screen(struct x
 	xenfb_do_update(info, x1, y1, x2 - x1, y2 - y1);
 }
 
+static void xenfb_resize_screen(struct xenfb_info *info)
+{
+	if (xenfb_queue_full(info))
+		return;
+
+	info->resize_dpy = 0;
+	xenfb_do_resize(info);
+	xenfb_refresh(info, 0, 0, info->xres, info->yres);
+}
+
 static int xenfb_thread(void *data)
 {
 	struct xenfb_info *info = data;
@@ -217,6 +253,9 @@ static int xenfb_thread(void *data)
 		if (info->dirty) {
 			info->dirty = 0;
 			xenfb_update_screen(info);
+		}
+		if (info->resize_dpy) {
+			xenfb_resize_screen(info);
 		}
 		wait_event_interruptible(info->wq,
 			kthread_should_stop() || info->dirty);
@@ -413,6 +452,45 @@ static int xenfb_mmap(struct fb_info *fb
 	return 0;
 }
 
+static int
+xenfb_check_var(struct fb_var_screeninfo *var, struct fb_info *info)
+{
+	struct xenfb_info *xenfb_info;
+
+	xenfb_info = info->par;
+
+	if (!xenfb_info->feature_resize) {
+		if (var->xres == XENFB_WIDTH && var->yres == XENFB_HEIGHT
+				&& var->bits_per_pixel == xenfb_info->page->depth) {
+			return 0;
+		}
+		return -EINVAL;
+	}
+	if (var->bits_per_pixel == xenfb_info->page->depth && 
+			XENFB_SCAN_LINE_LEN >= var->xres && 
+			xenfb_mem_len >= (var->xres * var->yres * (xenfb_info->page->depth / 8))) {
+		var->xres_virtual = var->xres;
+		var->yres_virtual = var->yres;
+		return 0;
+	}
+	return -EINVAL;
+}
+
+static int xenfb_set_par(struct fb_info *info)
+{
+	struct xenfb_info *xenfb_info;
+
+	xenfb_info = info->par;
+
+	if (xenfb_info->xres != info->var.xres || 
+			xenfb_info->yres != info->var.yres) {
+		xenfb_info->resize_dpy = 1;
+		xenfb_info->xres = info->var.xres_virtual = info->var.xres;
+		xenfb_info->yres = info->var.yres_virtual = info->var.yres;
+	}
+	return 0;
+}
+
 static struct fb_ops xenfb_fb_ops = {
 	.owner		= THIS_MODULE,
 	.fb_setcolreg	= xenfb_setcolreg,
@@ -420,6 +498,8 @@ static struct fb_ops xenfb_fb_ops = {
 	.fb_copyarea	= xenfb_copyarea,
 	.fb_imageblit	= xenfb_imageblit,
 	.fb_mmap	= xenfb_mmap,
+	.fb_check_var	= xenfb_check_var,
+	.fb_set_par     = xenfb_set_par,
 };
 
 static irqreturn_t xenfb_event_handler(int rq, void *dev_id,
@@ -451,16 +531,29 @@ static int __devinit xenfb_probe(struct 
 	struct xenfb_info *info;
 	struct fb_info *fb_info;
 	int ret;
+	int val;
 
 	info = kzalloc(sizeof(*info), GFP_KERNEL);
 	if (info == NULL) {
 		xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure");
 		return -ENOMEM;
 	}
+
+	// Determine video memory size based on feature support
+	xenfb_mem_len = XENFB_WIDTH * XENFB_HEIGHT * XENFB_DEPTH / 8;
+	if (xenbus_scanf(XBT_NIL, dev->otherend, 
+				"xenfb-feature-resize", "%d", &val) < 0)
+		val = 0;
+	info->feature_resize = val;
+	if (info->feature_resize)
+		xenfb_mem_len = XENFB_FRAME_BUFFER_LEN;
+
 	dev->dev.driver_data = info;
 	info->xbdev = dev;
 	info->irq = -1;
 	info->x1 = info->y1 = INT_MAX;
+	info->xres = XENFB_WIDTH;
+	info->yres = XENFB_HEIGHT;
 	spin_lock_init(&info->dirty_lock);
 	mutex_init(&info->mm_lock);
 	init_waitqueue_head(&info->wq);
@@ -504,9 +597,10 @@ static int __devinit xenfb_probe(struct 
 	fb_info->screen_base = info->fb;
 
 	fb_info->fbops = &xenfb_fb_ops;
-	fb_info->var.xres_virtual = fb_info->var.xres = info->page->width;
-	fb_info->var.yres_virtual = fb_info->var.yres = info->page->height;
+	fb_info->var.xres_virtual = fb_info->var.xres = info->xres;
+	fb_info->var.yres_virtual = fb_info->var.yres = info->yres;
 	fb_info->var.bits_per_pixel = info->page->depth;
+	fb_info->var.pixclock = XENFB_PIXCLOCK;
 
 	fb_info->var.red = (struct fb_bitfield){16, 8, 0};
 	fb_info->var.green = (struct fb_bitfield){8, 8, 0};
@@ -572,6 +666,8 @@ static int xenfb_resume(struct xenbus_de
 
 	xenfb_disconnect_backend(info);
 	xenfb_init_shared_page(info);
+	if (info->feature_resize)
+		info->resize_dpy = 1;
 	return xenfb_connect_backend(dev, info);
 }
 
@@ -600,19 +696,30 @@ static void xenfb_init_shared_page(struc
 static void xenfb_init_shared_page(struct xenfb_info *info)
 {
 	int i;
-
+	int j;
+	int entries_per_pd;
+
+	entries_per_pd = PAGE_SIZE/sizeof(unsigned long);
+	
 	for (i = 0; i < info->nr_pages; i++)
 		info->pages[i] = vmalloc_to_page(info->fb + i * PAGE_SIZE);
 
-	for (i = 0; i < info->nr_pages; i++)
-		info->mfns[i] = vmalloc_to_mfn(info->fb + i * PAGE_SIZE);
-
 	info->page->pd[0] = vmalloc_to_mfn(info->mfns);
 	info->page->pd[1] = 0;
+	for ( j = i = 0; i < info->nr_pages; i++) {
+		info->mfns[i] = vmalloc_to_mfn(info->fb + i * PAGE_SIZE);
+		if ( i && i % entries_per_pd == 0 ) {
+			j++;
+			info->page->pd[j] = vmalloc_to_mfn(&info->mfns[i]);
+		}
+	}
 	info->page->width = XENFB_WIDTH;
 	info->page->height = XENFB_HEIGHT;
 	info->page->depth = XENFB_DEPTH;
-	info->page->line_length = (info->page->depth / 8) * info->page->width;
+	if (info->feature_resize)
+		info->page->line_length = (info->page->depth / 8) * XENFB_SCAN_LINE_LEN;
+	else
+		info->page->line_length = (info->page->depth / 8) * XENFB_WIDTH;
 	info->page->mem_length = xenfb_mem_len;
 	info->page->in_cons = info->page->in_prod = 0;
 	info->page->out_cons = info->page->out_prod = 0;
diff -r 61c96456a3e1 include/xen/interface/io/fbif.h
--- a/include/xen/interface/io/fbif.h	Thu Dec 20 16:58:14 2007 +0000
+++ b/include/xen/interface/io/fbif.h	Sat Jan 05 11:08:35 2008 -0700
@@ -50,12 +50,26 @@ struct xenfb_update
     int32_t height; /* rect height */
 };
 
+/*
+ * Framebuffer resize notification event
+ * Capable backend sets feature-resize in xenstore.
+ */
+#define XENFB_TYPE_RESIZE 3
+
+struct xenfb_resize
+{
+    uint8_t type;    /* XENFB_TYPE_RESIZE */
+    int32_t width;   /* xres */
+    int32_t height;  /* yres */
+};
+
 #define XENFB_OUT_EVENT_SIZE 40
 
 union xenfb_out_event
 {
     uint8_t type;
     struct xenfb_update update;
+    struct xenfb_resize resize;
     char pad[XENFB_OUT_EVENT_SIZE];
 };
 
@@ -111,8 +125,12 @@ struct xenfb_page
      * PAGE_SIZE / sizeof(*pd) bytes.  With PAGE_SIZE == 4096 and
      * sizeof(unsigned long) == 4, that's 4 Megs.  Two directory
      * pages should be enough for a while.
+     *
+     * Increased to 3 to support 1280x1024 resolution on a 64bit system
+     *  (1280*1024*4)/PAGE_SIZE = 1280 pages required
+     *  PAGE_SIZE/64bit long = 512 pages per page directory
      */
-    unsigned long pd[2];
+    unsigned long pd[3];
 };
 
 /*