Virtualbox: OS13.1 Host with 2 screens, 1 screen simply disappears

Hi there,

I have installed on a OS13.1 64 bit host in virtualbox a OS 13.1 64 bit guest. As I have 2 physical screens I have set the parameters in Virtual Box Manager to 2 screens. After the installation I installed the guest additions and everything seemed to run quite well.

In my 2. virtual machine I have Win7 64 bit running as a guest, also supporting 2 screens, each screen in its own window, without any problems.

MY PC has in total 16GB of ram; the Win7 guest can use 8 GB thereof and the OS13.1 guest 4GB. So 4gb are left for the host.
My AMD processor has 6 kernels, so I have given 3 for the WIN and 2 for the OS13.1 guest with an execution cap of 90% for both clients.
The Win client runs on desktop 1 and the OS client on desktop 2 of the host.

Whenever I switch from the OS client desktop to the win desktop, work some time there and then go back to the OS desktop, the 2. window of the OS13.1 guest is gone and to get it back, I have to restart the client completely. Just doing a restart does not work !

The runtime attributes of the session information of the OS13.1 guest before and after is equal:

**Runtime Attributes**

Screen Resolution 1     1904x961x32 @1904,0
Screen Resolution 2     1904x961x32 @0,0
VM Uptime                   0d 01:17:35
Clipboard Mode             Bidirectional
Drag and Drop Mode      Bidirectional
VT-x/AMD-V                  Active
Nested Paging               Active
Unrestricted Execution   Inactive
Paravirtualization Interface   KVM
Guest Additions             5.0.4_SUSE r102546
Guest OS Type               Linux 2.6 / 3.x / 4.x (64-bit)
Remote Desktop Server Port     Not Available

I also have always the problem that the system forgets which screen is #0 and which is #1. In System Settings/ Hardware/Display and Monitor/Display configuration I always find after starting the OS guest VBOX1 as left screen and VBOX0 as right screen. I can change it manually and apply the changes and it works during the session, but the system forgets this change - in the next session Vbox1 is again on the left and VBOX0 on the right.

The right window always disappears as described above, whether its vbox0 or vbox1, does not matter. I only mention this 2. problem it, as I assume it could have a common reason and enlighten the main problem. If it should turn out, that its isolate from the other problem I will create its own thread.


I think I have to clarify these 2 sentences a bit, as it obviously is a bit confusing :wink: :

I have to start a new virtual box session to get both screen windows back. A Restart from inside the OS13.1 guest keeps the current virtual box session and simply restarts the OS13.1 guest - without success as the 2. window does not appear again.


Hi there,

found a temporary solution :

I switched back to 1 screen setting in the VB Manager and (Option Autoresize Guestdisplay) resized the window each time after boot onto a width that covers both screens. Perfect solution.

BUT … that worked until this morning an “update” (better: “killdate”) destroyed it: The option “Autoresize” still exists (is not grayed out) but has no more effect. The system informed me that “VBoxClient the VirtualBox Kernel is n…” ! I guess it wants to say “not running” or similar, but the professional output method wanted to be diplomatic and hides the bad news … letting the user assume it would not fit in the message window and an automatic line wrap would not be supported in KDE message windows . . .

There is always trouble with these Guest Additions, so it let me already assume that Oracle has professional developers are messing it up intentionally!?

Will try to get the old configuration back. If it will not work, I will use a backup of the virtual machine and switch off the update procedures.



I found a solution to get my 2 screens back in the OS guest. Whether they will stay or disappear again !?!?! Good question, will report about it in a few hours.

I installed the patterns “Base Development”, “C/C++ Development” and “Linux Kernel Development” as someone on the internet suggested it. Afterwards I started with the help of the File Manager in Super User mode in the device VBOXADDITIONS the file and rebooted the system afterwards. Now its running again on both screens and no more “diplomatic” messages.

I think a developer should define those files needed for the VB additions and change the dependencies lists , so that it automatically will be downloaded with the virtualbox guest package. I assume that I have download far too many MByte of files which are actually not needed to make those GuestAditions run, right ?


Ok problem solved, even the window does not disappear any more !

Vbox Additions 5.06 and the installation of those patterns brought the solution.