[vbox-dev] Monitor count limitations

Rūdolfs Bundulis rudolfs.bundulis at gmail.com
Wed Aug 27 16:03:34 UTC 2014


After experimenting with different monitor amounts, I'm moving towards some
conclusions and would be glad to get some confirmation. It seems that even
if the displays require more memory than 256 MB the machine still launches
but seems that the hint to use 1920x1080 is ignored and 1152x862 is used.
So is it safe to assume that VirtualBox tries to find the maximum
 resolution for which it can fit all the framebuffers for all the displays
in the video memory? If I launch a machine with 8 monitors then it seems to
handle full hd, when i increase the display number, it reduces the
resolution, on 25 monitors i get only one (assuming there is not enoguh
memory even for 800x600x25?). Is it possible to recompile virtual box from
source with increased video memory limit or are there other dependencies?

Best Regards,
Rudolfs Bundulis

2014-08-27 17:49 GMT+03:00 Rūdolfs Bundulis <rudolfs.bundulis at gmail.com>:

> Hi,
> I've run into some more issues with high monitor count on VirtualBox.
> Basically when selecting 25 displays it complains that at least 600
> something MB of VRAM is needed, but while the arrows in the display number
> box allow to select more than 8 monitors, seems that i can't go above 256
> mb in VRAM. Is this a hard limitation? Since the COM API also does not
> allow me to set more than that.
> Best Regards,
> Rudolfs Bundulis
> 2014-06-18 13:41 GMT+03:00 Rūdolfs Bundulis <rudolfs.bundulis at gmail.com>:
> Hi Klaus,
>> Thanks a lot for the clarification. I thought the same that it was just a
>> sanity limit, but in my case this is really needed. Then I guess will be
>> able to do the same with the COM API, thanks a lot again.
>> 2014-06-18 13:13 GMT+03:00 Klaus Espenlaub <klaus.espenlaub at oracle.com>:
>> Hi Rūdolfs,
>>> On 18.06.2014 11:48, Rūdolfs Bundulis wrote:
>>> > Hi,
>>> >
>>> > I'm developing a system that needs to run a headless VM with a large
>>> > number of attached monitors - currently the GUI has the limit to set
>>> > maximum monitor count to 8, I didn't check the COM API myself but I
>>> > suspect that it will not allow me to set the count greater than 8,
>>> while
>>> > browsing the VirtualBox sources show that the internal C macro is
>>> > defined to 64:
>>> >
>>> > /* this should be in sync with monitorCount <xsd:maxInclusive
>>> > value="8"/> in src/VBox/Main/xml/VirtualBox-settings-common.xsd */
>>> > #define VBOX_VIDEO_MAX_SCREENS 64
>>> Looks to me that this comment is simply outdated. Nothing more, nothing
>>> less.
>>> Many limits can be listed with "VBoxManage list systemproperties", and
>>> it shows 64.
>>> > Is there really a need to limit the count to 8? If I change the xml
>>> > schema file and increase the count from 8 to 64 and recompile would
>>> > there be any actual limitations in the VirtualBox core?
>>> There is a constant conflict in the GUI between sanity (i.e. protecting
>>> users against their stupidity - you can't believe how many people
>>> believe that more is better, even if it's a giant waste of resources
>>> instead) and allowing expert users to go to the extreme. There are
>>> extremely few people out there who ever need to deal with more than 8
>>> monitors.
>>> In my quick test I could use the GUI to select 20 monitors - sure, the
>>> slider doesn't allow that, but one can enter the number or use the
>>> up/down arrows. This needs 256MB of VRAM, which this high number
>>> automatically unlocks.
>>> Klaus
>>> _______________________________________________
>>> vbox-dev mailing list
>>> vbox-dev at virtualbox.org
>>> https://www.virtualbox.org/mailman/listinfo/vbox-dev
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://www.virtualbox.org/pipermail/vbox-dev/attachments/20140827/7600affd/attachment.html 

More information about the vbox-dev mailing list