1 files changed, 16 insertions, 9 deletions

diff --git a/hw/display/vga.c b/hw/display/vga.c
index 30facc6..892fedc 100644
--- a/hw/display/vga.c
+++ b/hw/display/vga.c
@@ -1487,7 +1487,7 @@ static void vga_draw_graphic(VGACommonState *s, int full_update)
     uint8_t *d;
     uint32_t v, addr1, addr;
     vga_draw_line_func *vga_draw_line = NULL;
-    bool share_surface, force_shadow = false;
+    bool allocate_surface, force_shadow = false;
     pixman_format_code_t format;
 #if HOST_BIG_ENDIAN
     bool byteswap = !s->big_endian_fb;
@@ -1609,10 +1609,10 @@ static void vga_draw_graphic(VGACommonState *s, int full_update)
      */
     format = qemu_default_pixman_format(depth, !byteswap);
     if (format) {
-        share_surface = dpy_gfx_check_format(s->con, format)
-            && !s->force_shadow && !force_shadow;
+        allocate_surface = !dpy_gfx_check_format(s->con, format)
+            || s->force_shadow || force_shadow;
     } else {
-        share_surface = false;
+        allocate_surface = true;
     }
 
     if (s->params.line_offset != s->last_line_offset ||
@@ -1620,7 +1620,7 @@ static void vga_draw_graphic(VGACommonState *s, int full_update)
         height != s->last_height ||
         s->last_depth != depth ||
         s->last_byteswap != byteswap ||
-        share_surface != is_buffer_shared(surface)) {
+        allocate_surface != surface_is_allocated(surface)) {
         /* display parameters changed -> need new display surface */
         s->last_scr_width = disp_width;
         s->last_scr_height = height;
@@ -1635,14 +1635,14 @@ static void vga_draw_graphic(VGACommonState *s, int full_update)
         full_update = 1;
     }
     if (surface_data(surface) != s->vram_ptr + (s->params.start_addr * 4)
-        && is_buffer_shared(surface)) {
+        && !surface_is_allocated(surface)) {
         /* base address changed (page flip) -> shared display surfaces
          * must be updated with the new base address */
         full_update = 1;
     }
 
     if (full_update) {
-        if (share_surface) {
+        if (!allocate_surface) {
             surface = qemu_create_displaysurface_from(disp_width,
                     height, format, s->params.line_offset,
                     s->vram_ptr + (s->params.start_addr * 4));
@@ -1655,7 +1655,7 @@ static void vga_draw_graphic(VGACommonState *s, int full_update)
 
     vga_draw_line = vga_draw_line_table[v];
 
-    if (!is_buffer_shared(surface) && s->cursor_invalidate) {
+    if (surface_is_allocated(surface) && s->cursor_invalidate) {
         s->cursor_invalidate(s);
     }
 
@@ -1707,7 +1707,7 @@ static void vga_draw_graphic(VGACommonState *s, int full_update)
         if (update) {
             if (y_start < 0)
                 y_start = y;
-            if (!(is_buffer_shared(surface))) {
+            if (surface_is_allocated(surface)) {
                 uint8_t *p;
                 p = vga_draw_line(s, d, addr, width, hpel);
                 if (p) {
@@ -1762,6 +1762,13 @@ static void vga_draw_blank(VGACommonState *s, int full_update)
     if (s->last_scr_width <= 0 || s->last_scr_height <= 0)
         return;
 
+    if (!surface_is_allocated(surface)) {
+        /* unshare buffer, otherwise the blanking corrupts vga vram */
+        surface = qemu_create_displaysurface(s->last_scr_width,
+                                             s->last_scr_height);
+        dpy_gfx_replace_surface(s->con, surface);
+    }
+
     w = s->last_scr_width * surface_bytes_per_pixel(surface);
     d = surface_data(surface);
     for(i = 0; i < s->last_scr_height; i++) {