Re: [Qemu-devel] Re: [PATCH] Fix display breakage when resizing the screen

[Avi Kivity]

Anthony Liguori wrote:
> Avi Kivity wrote:
> > When the vga resolution changes, a new display surface is not allocated
> > immediately; instead that is deferred until the next update.  However,
> > if we're running without a display client attached, that won't happen
> > and the next bitblt is likely to cause a segfault by overflowing the
> > display surface.
> >
> > Fix by reallocating the display immediately when the resolution changes.
> >
> > Tested with (Windows|Linux) x (cirrus|std) x (curses|sdl).
> >
> > Signed-off-by: Avi Kivity <address@hidden
>
> This patch breaks VC switching with -curses.

Can someone explain what DisplaySurface::width means when using curses?

It is initialized to a pixel value:

  ds->surface = qemu_create_displaysurface_from(640, 400, 0, 0, 
(uint8_t*) screen);

then read in from the current surface:

static void curses_resize(DisplayState *ds)
{
   if (ds_get_width(ds) == gwidth && ds_get_height(ds) == gheight)
       return;

   gwidth = ds_get_width(ds);
   gheight = ds_get_height(ds);

   curses_calc_pad();
   ds->surface->width = width * FONT_WIDTH;
   ds->surface->height = height * FONT_HEIGHT;
}

But curses_calc_pad() does

static void curses_calc_pad(void)
{
   if (is_fixedsize_console()) {
       width = gwidth;
       height = gheight;
   } else {
       width = COLS;
       height = LINES;
   }

If !is_fixedsize_console(), then the global width takes on a character 
cell count, later multiplied by FONT_WIDTH to become a pixel value 
again.  But if is_fixedsize_console() is true (which happens to be the 
case here), then the global width is a pixel value (from gwidth), and 
when multiplied by FONT_WIDTH it becomes nonsense.  Repeated calls to 
curses_resize() will inflate the value to hell.

--
error compiling committee.c: too many arguments to function