Unable to enable additional virtual monitors for Linux guest

Discussions about using Linux guests in VirtualBox.
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Pragmatic
Posts: 2
Joined: 19. Feb 2018, 14:43

Unable to enable additional virtual monitors for Linux guest

Post by Pragmatic »

I am new to macOS, so debugging things is more difficult as I learn the various ways of doing so. That said, I am open to any suggestions on how to debug user applications on this platform.

I have a Linux Mint (17.3) guest OS that works great for the most part (shared folders, networking, monitor resizing, etc). However, I am not able to enable more than one virtual monitor. On the host I have set the "Monitor Count" setting to two and restarted the guest for good measure. When the VBox guest window is not in fullscreen mode the View drop-down menu shows an enable option for Virtual Screen 2. However, nothing happens if I try to enable this additional monitor. In contrast, when the VBox guest window is in fullscreen mode the same drop-down menu shows the "Use Host Screen X" options for where to place the new virtual monitor. Again, however, nothing happens if I attempt to select any of these provided options. The only effect I observe is when I try to select the "Use Host Screen X" option to corresponds to the same physical monitor on which VBox is currently open. In this case the guest window will remove itself from fullscreen mode and then immediately go back into fullscreen mode.

I do have guest additions installed but am happy to provide whatever information necessary to verify this. Here are the bits that I know about:

I am using VirtualBox version 5.2.6 on the macOS host (10.12.6). I installed the guest additions by virtually inserting the ISO, but from the logs below it seems version 5.0.4 was installed.

A few xbox-related kernel modules are loaded:

Code: Select all

$ lsmod | grep box
vboxsf                 45056  1 
vboxguest             278528  7 vboxsf
vboxvideo              16384  1 
drm                   344064  3 vboxvideo
All seems to be okay in the system log, save for the very first vbox listing, which report that vboxvideo failed verification. However, it was still loaded per the output of lsmod above.

Code: Select all

[   12.324950] vboxvideo: module verification failed: signature and/or  required key missing - tainting kernel
[   12.332003] [drm] Initialized vboxvideo 1.0.0 20090303 for 0000:00:02.0 on minor 0
[   12.369277] vboxguest: misc device minor 56, IRQ 20, I/O port d020, MMIO at 00000000f0400000 (size 0x400000)
[   12.369279] vboxguest: Successfully loaded version 5.0.4_LinuxMint (interface 0x00010004)
[   14.142779] vboxsf: Successfully loaded version 5.0.4_LinuxMint (interface 0x00010004)
[   14.144901] VBoxService 5.0.4_LinuxMint r102546 (verbosity: 0) linux.amd64 (Nov 10 2015 22:46:44) release log
[   14.144901] 00:00:00.000051 main     Log opened 2018-02-19T12:33:29.581446000Z
[   14.144945] 00:00:00.000125 main     OS Product: Linux
[   14.144964] 00:00:00.000148 main     OS Release: 3.19.0-32-generic
[   14.144983] 00:00:00.000167 main     OS Version: #37~14.04.1-Ubuntu SMP Thu Oct 22 09:41:40 UTC 2015
[   14.145002] 00:00:00.000186 main     OS Service Pack: #37~14.04.1-Ubuntu SMP Thu Oct 22 09:41:40 UTC 2015
[   14.145025] 00:00:00.000204 main     Executable: /usr/sbin/VBoxService
[   14.145025] 00:00:00.000205 main     Process ID: 1323
[   14.145025] 00:00:00.000205 main     Package type: LINUX_64BITS_GENERIC (OSE)
[   14.146618] 00:00:00.001791 main     5.0.4_LinuxMint r102546 started. Verbose level = 0
[   14.153613] 00:00:00.008772 automount VBoxServiceAutoMountWorker: Shared folder "vmshare" was mounted to "/media/sf_vmshare"
I poke around in the macOS application "Console" but did not find anything reporting an error. Of course, I am new to using it and may have missed something important (or did not look in the right places).
socratis
Site Moderator
Posts: 27330
Joined: 22. Oct 2010, 11:03
Primary OS: Mac OS X other
VBox Version: PUEL
Guest OSses: Win(*>98), Linux*, OSX>10.5
Location: Greece

Re: Unable to enable additional virtual monitors for Linux guest

Post by socratis »

Moving to "Linux Guests" from "OSX Hosts" since the problem seems to be guest specific.
Pragmatic wrote:restarted the guest for good measure.
You changed the hardware. You have to restart the guest. The virtual monitors are not a on-the-fly change.
Pragmatic wrote:A few xbox-related kernel modules are loaded:
But we don't know if they're the distro supplied or the VirtualBox ones. "VBoxControl -version" could clarify this. As well as the log...
Pragmatic wrote:
VBoxService 5.0.4_LinuxMint r102546
Scratch that. We don't need the log, the information is there. You need to uninstall the distro-made GAs and install the ones that come with your VirtualBox installation.
Pragmatic wrote:I poke around in the macOS application "Console" but did not find anything reporting an error.
VirtualBox (as an application) is working fine, nothing to report. The log you're looking for is the VBox.log, if you right-click on the VM in the VirtualBox Manager, Show Log. If you update your GAs, and you decide to include the VBox.log, please ZIP it first...
Do NOT send me Personal Messages (PMs) for troubleshooting, they are simply deleted.
Do NOT reply with the "QUOTE" button, please use the "POST REPLY", at the bottom of the form.
If you obfuscate any information requested, I will obfuscate my response. These are virtual UUIDs, not real ones.
Pragmatic
Posts: 2
Joined: 19. Feb 2018, 14:43

Re: Unable to enable additional virtual monitors for Linux guest

Post by Pragmatic »

socratis wrote:Moving to "Linux Guests" from "OSX Hosts" since the problem seems to be guest specific.
The thread is still in the OS X hosts forum. I agree, it does appear to be an isolated Linux guest issue.
You changed the hardware. You have to restart the guest. The virtual monitors are not a on-the-fly change.
Ah. Good to know. A physical monitor hot-plug is supported, so I was unsure if the virtual ones were.
Scratch that. We don't need the log, the information is there. You need to uninstall the distro-made GAs and install the ones that come with your VirtualBox installation.
Ah. Good catch. I tried it both ways originally. I began wondering why I had not done more troubleshooting with the 5.2.6 GAs installed. Then I remembered that after installing them the VM would no longer boot. Actually, this happened on Linux Mint 17.3, 18.3, Ubuntu 17.04, and Debian 9.0. Considering the lowest common denominator here is Debian, perhaps there is an issue booting that distro with the latest (perhaps macOS-only) release?

Logs attached. The machine shows the BIOS splash screen and the Linux Mint logo once the kernel is loaded, but nothing happens after that (the logo disappears). This observation corresponds to roughly second 12 in the VirtualBox log (attached). At this point the log only reports graphics-related things until I force a power-off.

Virtualbox attempts to launch two windows per its Display setting configuration. I set the monitor count back to 1 to limit the number of variables but it had no effect.


----- EDIT
Considering the problem seemed related to video, I went in and disabled 3D acceleration in display settings. This change allowed the system to boot. I went back and set the monitor count to 2 and that also worked. Working log attached.
Attachments
LM17.3_VBox_working.zip
(28.08 KiB) Downloaded 11 times
LM17.3_VBox.zip
(36.43 KiB) Downloaded 11 times
socratis
Site Moderator
Posts: 27330
Joined: 22. Oct 2010, 11:03
Primary OS: Mac OS X other
VBox Version: PUEL
Guest OSses: Win(*>98), Linux*, OSX>10.5
Location: Greece

Re: Unable to enable additional virtual monitors for Linux guest

Post by socratis »

Pragmatic wrote:The thread is still in the OS X hosts forum.
D'oh! :shock: I actually moved it this time, thanks for pointing that out.
Pragmatic wrote:more troubleshooting with the 5.2.6 GAs installed. Then I remembered that after installing them the VM would no longer boot.
Yeah... right... There was a problem with the 5.2.6 GAs. Check the "Important" paragraph in the "Downloads" page, or download the latest test build.
Pragmatic wrote:I went in and disabled 3D acceleration in display settings. This change allowed the system to boot.
That would be another workaround for the 5.2.6 GAs.
Pragmatic wrote:I went back and set the monitor count to 2 and that also worked.
Can you try with the latest test build and see if it works or not? And under what conditions?
Do NOT send me Personal Messages (PMs) for troubleshooting, they are simply deleted.
Do NOT reply with the "QUOTE" button, please use the "POST REPLY", at the bottom of the form.
If you obfuscate any information requested, I will obfuscate my response. These are virtual UUIDs, not real ones.
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