Dynamic modes support for xenfb (1 of 2)

diff -r f33328217eee tools/ioemu/hw/xenfb.c
@@ -516,6 +516,16 @@ static void xenfb_on_fb_event(struct xen
 			}
 			xenfb_guest_copy(xenfb, x, y, w, h);
 			break;
+		case XENFB_TYPE_RESIZE:
+			xenfb->width  = event->resize.width;
+			xenfb->height = event->resize.height;
+			xenfb->row_stride = event->resize.stride;
+			dpy_colourdepth(xenfb->ds, xenfb->depth);
+			dpy_resize(xenfb->ds, xenfb->width, xenfb->height, xenfb->row_stride);
+			if (xenfb->ds->shared_buf)
+				dpy_setdata(xenfb->ds, xenfb->pixels);
+			xenfb_invalidate(xenfb);
+			break;
 		}
 	}
 	xen_mb();		/* ensure we're done with ring contents */

@@ -680,6 +690,7 @@ static int xenfb_read_frontend_fb_config
 static int xenfb_read_frontend_fb_config(struct xenfb *xenfb) {
 	struct xenfb_page *fb_page;
 	int val;
+	int videoram;
 
         if (xenfb_xs_scanf1(xenfb->xsh, xenfb->fb.otherend, "feature-update",
                             "%d", &val) < 0)

@@ -702,10 +713,30 @@ static int xenfb_read_frontend_fb_config
         /* TODO check for consistency with the above */
         xenfb->fb_len = fb_page->mem_length;
         xenfb->row_stride = fb_page->line_length;
+
+        /* Protect against hostile frontend, limit fb_len to max allowed */
+        if (xenfb_xs_scanf1(xenfb->xsh, xenfb->fb.nodename, "videoram", "%d",
+                            &videoram) < 0)
+                videoram = 0;
+        videoram = videoram * 1024 * 1024;
+        if (videoram && xenfb->fb_len > videoram) {
+                fprintf(stderr, "Framebuffer requested length of %d exceeded allowed %d\n",
+                        xenfb->fb_len, videoram);
+                xenfb->fb_len = videoram;
+                if (xenfb->row_stride * xenfb->height > xenfb->fb_len)
+                        xenfb->height = xenfb->fb_len / xenfb->row_stride;
+        }
         fprintf(stderr, "Framebuffer depth %d width %d height %d line %d\n",
                 fb_page->depth, fb_page->width, fb_page->height, fb_page->line_length);
         if (xenfb_map_fb(xenfb, xenfb->fb.otherend_id) < 0)
 		return -1;
+
+        /* Indicate we have the frame buffer resize feature */
+        xenfb_xs_printf(xenfb->xsh, xenfb->fb.nodename, "feature-resize", "1");
+
+        /* Tell kbd pointer the screen geometry */
+        xenfb_xs_printf(xenfb->xsh, xenfb->kbd.nodename, "width", "%d", xenfb->width);
+        xenfb_xs_printf(xenfb->xsh, xenfb->kbd.nodename, "height", "%d", xenfb->height);
 
         if (xenfb_switch_state(&xenfb->fb, XenbusStateConnected))
                 return -1;

diff -r f33328217eee xen/include/public/io/fbif.h
@@ -50,12 +50,28 @@ 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;   /* width in pixels */
+    int32_t height;  /* height in pixels */
+    int32_t stride;  /* stride in bytes */
+    int32_t depth;   /* depth in bits */
+};
+
 #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];
 };
 

@@ -109,15 +125,17 @@ struct xenfb_page
      * Each directory page holds PAGE_SIZE / sizeof(*pd)
      * framebuffer pages, and can thus map up to PAGE_SIZE *
      * 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.
+     * sizeof(unsigned long) == 4/8, that's 4 Megs 32 bit and 2 Megs
+     * 64 bit.  256 directories give enough room for a 512 Meg
+     * framebuffer with a max resolution of 12,800x10,240.  Should
+     * be enough for a while with room leftover for expansion.
      */
-    unsigned long pd[2];
+    unsigned long pd[256];
 };
 
 /*
- * Wart: xenkbd needs to know resolution.  Put it here until a better
- * solution is found, but don't leak it to the backend.
+ * Wart: xenkbd needs to know default resolution.  Put it here until a
+ * better solution is found, but don't leak it to the backend.
  */
 #ifdef __KERNEL__
 #define XENFB_WIDTH 800