Hi, > Which guest OS are you using? Which driver did you install (for those > OSes which allow selecting)? 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.
> Barely... the above formula gives 223MB already, and if the Windows > driver really need the mentioned amount of offscreen memory you'd run > out of VRAM. I'd use VBoxHeadless to try this out actually, because it > doesn't have any of those annoying safeguards to protect users from > shooting themselves in the foot. 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. Best Regards, Rudolfs Bundulis 2014-08-27 20:11 GMT+03:00 Klaus Espenlaub <[email protected]>: > On 27.08.2014 18:38, Rūdolfs Bundulis wrote: > > Hi Klaus, > > > > Thanks again for the fast response. Well, this is a university research > > project to build monitor walls without the underlying hardware, so I > > guess its reasonable that I am breaking some limits that should be > > normal in a normal use case. > > As long as you're only going for high monitor counts, that's nothing > unexpected. > > > Regarding 3D, when I installed guest additions I checked the Direct3D > > box but I dont have the "Enable 3D acceleration" checkbox checked in > > the VirtualBox manager. Should I reinstall the guest additions without > > Direct3D? > > Strange... I wonder why the GUI is so eager with insanely high VRAM > proposals. It should only care about the checkbox, because if that's not > set then there is no 3D, period. > > From what I remember, the "rule of thumb" for the absolute minimum VRAM > size (in bytes) is (x*y*4+4096+1048576)*count. At least it was accurate > with the X11 driver, and the GUI seems to agree. It seems the XPDM > driver needs twice that much (because Windows needs one offscreen > surface), and with the WDDM driver it needs thrice that much (two > offscreen surfaces). > > Which guest OS are you using? Which driver did you install (for those > OSes which allow selecting)? > > > And more important, is it actually possible to fit 25 full hd > > (1920x1080) framebuffers in the video ram if it is only 256mb inside > > virtualbox? I could try to recompile from sources with lets say 1GB if > > redefining the video memory macro does not break other stuff. > > Barely... the above formula gives 223MB already, and if the Windows > driver really need the mentioned amount of offscreen memory you'd run > out of VRAM. I'd use VBoxHeadless to try this out actually, because it > doesn't have any of those annoying safeguards to protect users from > shooting themselves in the foot. > > Increasing the VRAM size by recompiling will cause trouble, as it would > need drastic changes to the memory layout (PCI memory hole, ...), and > I'm quite sure that we looked at it and considered it too much effort. > Everything is doable in the end, that's the good and bad thing about > software :) > > Klaus > > > Best Regards, > > Rudolfs Bundulis > > From: Klaus Espenlaub > > Sent: 2014.08.27. 19:05 > > To: [email protected] > > Subject: Re: [vbox-dev] Monitor count limitations > > Hi Rūdolfs, > > > > On 27.08.2014 16:49, Rūdolfs Bundulis wrote: > >> 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. > > > > Sounds like you have 3D enabled - then the GUI does a little too simple > > maths, extrapolating the necessary space beyond sanity. It's only a > > proposal, not a hard "must have". Don't think anyone tried to go to such > > extremes, because it's just nonsense to expect even basic 3D able to > > cope with so many screens. > > > > If you disable 3D then the requirements should be a lot lower, in the > > order of what's needed to represent the pixels. > > > > Yes, there is currently a hard limit of 256 MiB VRAM, and we didn't find > > cases where it was absolutely necessary to have more. > > > > Klaus > >> Best Regards, > >> Rudolfs Bundulis > >> > >> > >> 2014-06-18 13:41 GMT+03:00 Rūdolfs Bundulis <[email protected] > >> <mailto:[email protected]>>: > >> > >> 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 > >> <[email protected] <mailto:[email protected]>>: > >> > >> 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 > [email protected] > https://www.virtualbox.org/mailman/listinfo/vbox-dev >
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