<div dir="ltr">Hi,<div><br></div><div><span style="font-family:arial,sans-serif;font-size:13px">> Which guest OS are you using? Which driver did you install (for those</span><br style="font-family:arial,sans-serif;font-size:13px">
<span style="font-family:arial,sans-serif;font-size:13px">> OSes which allow selecting)?</span><br></div><div>I am running Windows 7, but I seems that I also have a Xubuntu 14 machine and I could set up a Windows XP machine to see if that fits better. I installed the default guest additions package on both Windows 7 and Xubuntu, on Windows7 i checked the Direct3D checkbox.</div>
<div><br></div><div><span style="font-family:arial,sans-serif;font-size:13px">> Barely... the above formula gives 223MB already, and if the Windows</span><br style="font-family:arial,sans-serif;font-size:13px"><span style="font-family:arial,sans-serif;font-size:13px">> driver really need the mentioned amount of offscreen memory you'd run</span><br style="font-family:arial,sans-serif;font-size:13px">
<span style="font-family:arial,sans-serif;font-size:13px">> out of VRAM. I'd use VBoxHeadless to try this out actually, because it</span><br style="font-family:arial,sans-serif;font-size:13px"><span style="font-family:arial,sans-serif;font-size:13px">> doesn't have any of those annoying safeguards to protect users from</span><br style="font-family:arial,sans-serif;font-size:13px">
<span style="font-family:arial,sans-serif;font-size:13px">> shooting themselves in the foot.</span><br></div><div><span style="font-family:arial,sans-serif;font-size:13px"><br></span></div><div><span style="font-family:arial,sans-serif;font-size:13px">Ok that could explain why I don't get the full hd resolutions, I could be just simply running out of VRAM. VboxHeadless wont help, I already have a console app that starts the VM using the COM API and injects implementation for the IFramebuffer interfaces in each monitor and I capture the display surfaces. So it seems that 25 full hd displays on Windows is not possible.</span></div>
<div><span style="font-family:arial,sans-serif;font-size:13px"><br></span></div><div><span style="font-family:arial,sans-serif;font-size:13px">Best Regards,</span></div><div><span style="font-family:arial,sans-serif;font-size:13px">Rudolfs Bundulis</span></div>
<div><br></div></div><div class="gmail_extra"><br><br><div class="gmail_quote">2014-08-27 20:11 GMT+03:00 Klaus Espenlaub <span dir="ltr"><<a href="mailto:klaus.espenlaub@oracle.com" target="_blank">klaus.espenlaub@oracle.com</a>></span>:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div class="">On <a href="tel:27.08.2014" value="+37127082014">27.08.2014</a> 18:38, Rūdolfs Bundulis wrote:<br>
> Hi Klaus,<br>
><br>
> Thanks again for the fast response. Well, this is a university research<br>
> project to build monitor walls without the underlying hardware, so I<br>
> guess its reasonable that I am breaking some limits that should be<br>
> normal in a normal use case.<br>
<br>
</div>As long as you're only going for high monitor counts, that's nothing<br>
unexpected.<br>
<div class=""><br>
> Regarding 3D, when I installed guest additions I checked the Direct3D<br>
> box but I dont have the "Enable 3D acceleration" checkbox checked in<br>
> the VirtualBox manager. Should I reinstall the guest additions without<br>
> Direct3D?<br>
<br>
</div>Strange... I wonder why the GUI is so eager with insanely high VRAM<br>
proposals. It should only care about the checkbox, because if that's not<br>
set then there is no 3D, period.<br>
<br>
From what I remember, the "rule of thumb" for the absolute minimum VRAM<br>
size (in bytes) is (x*y*4+4096+1048576)*count. At least it was accurate<br>
with the X11 driver, and the GUI seems to agree. It seems the XPDM<br>
driver needs twice that much (because Windows needs one offscreen<br>
surface), and with the WDDM driver it needs thrice that much (two<br>
offscreen surfaces).<br>
<br>
Which guest OS are you using? Which driver did you install (for those<br>
OSes which allow selecting)?<br>
<div class=""><br>
> And more important, is it actually possible to fit 25 full hd<br>
> (1920x1080) framebuffers in the video ram if it is only 256mb inside<br>
> virtualbox? I could try to recompile from sources with lets say 1GB if<br>
> redefining the video memory macro does not break other stuff.<br>
<br>
</div>Barely... the above formula gives 223MB already, and if the Windows<br>
driver really need the mentioned amount of offscreen memory you'd run<br>
out of VRAM. I'd use VBoxHeadless to try this out actually, because it<br>
doesn't have any of those annoying safeguards to protect users from<br>
shooting themselves in the foot.<br>
<br>
Increasing the VRAM size by recompiling will cause trouble, as it would<br>
need drastic changes to the memory layout (PCI memory hole, ...), and<br>
I'm quite sure that we looked at it and considered it too much effort.<br>
Everything is doable in the end, that's the good and bad thing about<br>
software :)<br>
<div class="HOEnZb"><div class="h5"><br>
Klaus<br>
<br>
> Best Regards,<br>
> Rudolfs Bundulis<br>
> From: Klaus Espenlaub<br>
> Sent: <a href="tel:2014.08.27" value="+37120140827">2014.08.27</a>. 19:05<br>
> To: <a href="mailto:vbox-dev@virtualbox.org">vbox-dev@virtualbox.org</a><br>
> Subject: Re: [vbox-dev] Monitor count limitations<br>
> Hi Rūdolfs,<br>
><br>
> On <a href="tel:27.08.2014" value="+37127082014">27.08.2014</a> 16:49, Rūdolfs Bundulis wrote:<br>
>> Hi,<br>
>><br>
>> I've run into some more issues with high monitor count on VirtualBox.<br>
>> Basically when selecting 25 displays it complains that at least 600<br>
>> something MB of VRAM is needed, but while the arrows in the display<br>
>> number box allow to select more than 8 monitors, seems that i can't go<br>
>> above 256 mb in VRAM. Is this a hard limitation? Since the COM API also<br>
>> does not allow me to set more than that.<br>
><br>
> Sounds like you have 3D enabled - then the GUI does a little too simple<br>
> maths, extrapolating the necessary space beyond sanity. It's only a<br>
> proposal, not a hard "must have". Don't think anyone tried to go to such<br>
> extremes, because it's just nonsense to expect even basic 3D able to<br>
> cope with so many screens.<br>
><br>
> If you disable 3D then the requirements should be a lot lower, in the<br>
> order of what's needed to represent the pixels.<br>
><br>
> Yes, there is currently a hard limit of 256 MiB VRAM, and we didn't find<br>
> cases where it was absolutely necessary to have more.<br>
><br>
> Klaus<br>
>> Best Regards,<br>
>> Rudolfs Bundulis<br>
>><br>
>><br>
>> 2014-06-18 13:41 GMT+03:00 Rūdolfs Bundulis <<a href="mailto:rudolfs.bundulis@gmail.com">rudolfs.bundulis@gmail.com</a><br>
>> <mailto:<a href="mailto:rudolfs.bundulis@gmail.com">rudolfs.bundulis@gmail.com</a>>>:<br>
>><br>
>> Hi Klaus,<br>
>><br>
>> Thanks a lot for the clarification. I thought the same that it was<br>
>> just a sanity limit, but in my case this is really needed. Then I<br>
>> guess will be able to do the same with the COM API, thanks a lot again.<br>
>><br>
>><br>
>> 2014-06-18 13:13 GMT+03:00 Klaus Espenlaub<br>
>> <<a href="mailto:klaus.espenlaub@oracle.com">klaus.espenlaub@oracle.com</a> <mailto:<a href="mailto:klaus.espenlaub@oracle.com">klaus.espenlaub@oracle.com</a>>>:<br>
>><br>
>> Hi Rūdolfs,<br>
>><br>
>> On 18.06.2014 11:48, Rūdolfs Bundulis wrote:<br>
>> > Hi,<br>
>> ><br>
>> > I'm developing a system that needs to run a headless VM with<br>
>> a large<br>
>> > number of attached monitors - currently the GUI has the limit<br>
>> to set<br>
>> > maximum monitor count to 8, I didn't check the COM API myself<br>
>> but I<br>
>> > suspect that it will not allow me to set the count greater<br>
>> than 8, while<br>
>> > browsing the VirtualBox sources show that the internal C macro is<br>
>> > defined to 64:<br>
>> ><br>
>> > /* this should be in sync with monitorCount <xsd:maxInclusive<br>
>> > value="8"/> in<br>
>> src/VBox/Main/xml/VirtualBox-settings-common.xsd */<br>
>> > #define VBOX_VIDEO_MAX_SCREENS 64<br>
>><br>
>> Looks to me that this comment is simply outdated. Nothing more,<br>
>> nothing<br>
>> less.<br>
>><br>
>> Many limits can be listed with "VBoxManage list<br>
>> systemproperties", and<br>
>> it shows 64.<br>
>><br>
>> > Is there really a need to limit the count to 8? If I change<br>
>> the xml<br>
>> > schema file and increase the count from 8 to 64 and recompile<br>
>> would<br>
>> > there be any actual limitations in the VirtualBox core?<br>
>><br>
>> There is a constant conflict in the GUI between sanity (i.e.<br>
>> protecting<br>
>> users against their stupidity - you can't believe how many people<br>
>> believe that more is better, even if it's a giant waste of resources<br>
>> instead) and allowing expert users to go to the extreme. There are<br>
>> extremely few people out there who ever need to deal with more<br>
>> than 8<br>
>> monitors.<br>
>><br>
>> In my quick test I could use the GUI to select 20 monitors -<br>
>> sure, the<br>
>> slider doesn't allow that, but one can enter the number or use the<br>
>> up/down arrows. This needs 256MB of VRAM, which this high number<br>
>> automatically unlocks.<br>
>><br>
>> Klaus<br>
>><br>
><br>
<br>
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