Re: [Qemu-devel] [PULL 10/14] ui: fix VNC client throttling when audio capture is active

[Gerd Hoffmann]

  Hi,

> >>>>> VNC is protocol limited to uint16 for width/height size, and so is X11
> >>>>> so I imagine some exploding behavour would follow :-)
> >>>>
> >>>> Indeed, and even 2^16 x 2^16 * 32bpp is already 34 bits.  So perhaps we
> >>>> should limit VNC to 16384 pixels on each axis (maximum frame buffer size
> >>>> 1 GiB).
> >>>
> >>> Google says you can already get graphics cards that can do 15360x8640,
> >>> which is really quite close to that 16384 limit...
> >>
> >> Then we can do 32767 * 16384 * 4, but I'm a bit afraid of off-by-ones.
> > 
> > Simply limit it to 30000 * 20000 ?
> 
> That's too much (exceeds 2^31-1 at 32bpp), but yeah, 30720*17280 is
> twice what Peter found and it's safe.

We already have:

#define VNC_MAX_WIDTH ROUND_UP(2560, VNC_DIRTY_PIXELS_PER_BIT)
#define VNC_MAX_HEIGHT 2048

If the guest framebuffer is larger you'll get the upper left corner
only I think.  spice can handle larger resolutions.

cheers,
  Gerd