Windows 10 16:9 Resolutions

[JohnCork]

Hi there,

I have an Ubuntu 14.04 host which was running a Windows 8.1 guest atop VirtualBox 4.36 without any issues. I then upgraded VirtualBox to 5.0.20 in preparation for upgrading the Windows guest to version 10. After the upgrade to Windows 10 I installed the Guest additions in order to get the right resolution for my 1920*1080 laptop screen. However, after the guest additions were installed that resolution still wasn't available. In fact, no 16:9 resolutions seem to be available.

I've tried various combinations of the suggestions on the web for this issue but to no avail, i.e.:
- setting up of a custom video mode;
- setting the video mode hint;
- installing guest additions in safe mode;
- installing guest additions with/without 3d acceleration switched on;
- installing guest additions as administrator;
- installing guest additions in windows 7/8 compatibility mode.

What seems to be happening is that the guest additions installation progress bar gets to about 20% and asks for a reboot as if it has completed successfully.

Anyway, has anyone any suggestions for how to solve this or debug through it in some way to find the root cause?

Thanks in advance,

John.

[mpack]

In the GUI, set File|Preferences|Display|Max Guest Screen Size to None.

[JohnCork]

Hi mpack,

Thanks for your reply. I actually tried that too by way of this command:
VBoxManage setextradata global GUI/MaxGuestResolution any

I verified that the setting is showing as you described. This does give me a 1920*1440 resolution which I am using as a workaround but 1920*1080 still doesn't show up.

Regards,

John.

[mpack]

That setting won't cause any new display sizes to appear, it just stops it filtering out 16:9 sizes. What is the significance of 1920x1080? Is that the size of the host display? If so then note two things:

1. It's a VM - a separate PC running on virtual hardware. The size of the virtual display of course has no direct relationship with that of your host display.
2. You can't size the window to 1920x1080 because your host OS wants to add a caption bar. If you want to fill the entire screen you need to switch to fullscreen mode.

[JohnCork]

Yep, that's the size of the host display.

[mpack]

You responded while I was still editing my previous answer.

[JohnCork]

Apologies.

Yes, I can fill the entire screen no problem, (HOST+F), but can't get the Windows VM to show a 1920*1080 option in its resolutions dropdown, (even though it happily shows a 1920*1440 option.

[mpack]

As I said, you can only get a fullscreen display by switching to fullscreen mode. You can't size a window to fullscreen. This is a limitation of your host OS.

[JohnCork]

I think we might be talking past each other here - not sure the fullscreen mode is relevant to this issue. I guess what I'm trying to find out is why the 16:9 resolutions aren't available in the Windows10 guest when they were when it was a Windows8.1 guest running on the same host machine.

[mpack]

If you have enabled the setting I mentioned then widescreen display sizes should now be available in the guest. If they aren't then it's a problem in the guest. You might look to disable the Windows option to hide display settings that (it thinks) your display can't use.

VirtualBox emulates real, physical hardware. A real physical display is either widescreen or 4:3, not both, and that's what your Windows guest expects to be the case. So, you have to fiddle to disable its unwanted smarts.

p.s. You told me that fullscreen mode works properly, which led me to believe that you no longer had a problem with all 16:9 ratios.