Re: [Qemu-devel] [RFC 7/7] qxl: add allocator

[Gerd Hoffmann <kraxel@redhat.com>]

  Hi,

>  Right now qxl_render_update checks if the displaysurface buffer is not
>  shared, meaning it was allocated by qemu, and in this case it replaces
>  it with the flipped buffer.

I think we should first reqire spice-server 0.8.latest, so
update_area_complete is available unconditionally.  Then do any
displaysurface updates in that callback (or a bh kicked by that
callback).  Handle both shared & non-shared cases.  I think we also can
get rid of the flip buffer then and just use a non-shared displaysurface
in that case (and flip the upside-down qxl surface while copying to the
qemu displaysurface).

>  But right after that surface->data gets reset, by vga_hw_screen_dump:
>  vga_hw_screen_dump/console_select/qemu_resize_displaysurface/ds->allocator->resize_displaysurface/defaultallocator_resize_displaysurface/qemu_alloc_display
> 
>  Hence my line of thought that replacing the allocator with my own would
>  prevent this. Since you have misgivings about using our own allocator
>  that I don't know how to resolve, I'm instead doing a second
>  reallocation in our dpy_resize callback qxl.c:display_resize, in affect
>  it means that we have three allocations and three deallocations for every
>  screendump. Do you still think it's less ugly then an allocator? note
>  that I have sdl and vnc working with spice with my allocator scheme.
>  (just didn't test all three together yet).

IMHO that calls for a patch like this to get rid of the pointless
console_select() call:

--- a/console.c
+++ b/console.c
@@ -181,12 +181,14 @@ void vga_hw_screen_dump(const char *filename)

     /* There is currently no way of specifying which screen we want to
dump,
        so always dump the first one.  */
-    console_select(0);
+    if (previous_active_console && previous_active_console->index != 0) {
+        console_select(0);
+    }
     if (consoles[0] && consoles[0]->hw_screen_dump) {
         consoles[0]->hw_screen_dump(consoles[0]->hw, filename);
     }

-    if (previous_active_console) {
+    if (previous_active_console && previous_active_console->index != 0) {
         console_select(previous_active_console->index);
     }
 }


cheers,
  Gerd