[vbox-dev] Monitor count limitations

[Klaus Espenlaub]

BTW, the GUI uses the OS type to make its guesses and recommendations. 
you can exploit that, because the OS type is not used for much besides 
picking suitable defaults - so create the VM with the correct OS type, 
and later re-declare it to be Linux. That way the GUI doesn't try to be 
"helpful", and you should be able to reach the limits...

On 02.09.2014 15:12, Rūdolfs Bundulis wrote:
>     Look at the guest Computer/Properties/Device Manager/Display
>     Adapters/VirtualBox Graphics Adapter/Driver/Driver Details
>     XPDM files are VBoxVideo.sys and VBoxDisp.dll
>
>     XPDM requires less guest VRAM, it mostly needs VRAM for the screen
>     surface. With 256MB of VRAM it is able to support 24 or 25 monitors at
>     1920x1200x32 each.
>     One screen needs ~9MB, which gives a hard limit 256/9 ~= 28 screens. But
>     since some VRAM is needed for other purposes, it is better not to use
>     the maximum.
>     The performance will be probably a bit worse compared to the case when
>     each guest screen has enough VRAM for a full resolution offscreen
>     surface.
>
>     I just tested a VBoxHeadless VM with 24 monitors at 1920x1200 and 256 MB
>     of guest VRAM and it seems to work fine.
>
>
> Thanks a lot, I'll try that out, I guess, since I checked the Direct3D
> support in the guest additions I could be using WDDM, I'll verify it and
> if so make a clean install and try XPDM. Since my current test wall is
> 5x5 25 would be great.  I simply got confused when I found the code i
> pasted here in a post above in the Qt GUI that does a hard
> multiplication with 3 to calculate the needed video memory.
>
> Rudolfs