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

[Peter Maydell]

On 18 January 2018 at 14:46, Paolo Bonzini <address@hidden> wrote:
> On 18/01/2018 15:12, Daniel P. Berrange wrote:
>>> In addition to that, do we support a >= 2 GiB framebuffer at all? (Even
>>> with unsigned ints, Coverity would rightly complain about a truncated
>>> 32-bit multiplication being assigned to a 64-bit value).
>> client_width/client_height are values that are initialized from the
>> graphics card frontend config, and thus limited by amount of video
>> RAM QEMU allows.   bytes_per_pixel is limited to 8/16/32.
>>
>> So I think we're safe from 2GB overflow in any normal case.
>>
>> That said, VGA RAM size is configurable, so I'm curious what would happen
>> if someone configured an insanely large VGA RAM and asked for a big frame
>> buffer in guest.
>>
>> 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...

thanks
-- PMM