Virtualization


VirtualBox on Windows: Stuck in capture mode as the keyboard does not have a right Ctrl button

Recently, we got a laptop that did not have a right Ctrl button and we found out after we started a VM with no Guest Additions installed.
Because of these two factors we could not escape the VM capture mode and return to the host OS.

To resolve the issue, we pressed Alt+Ctrl+Del to force the window to escape by entering that specialised Windows security screen and the hit Cancel.
Then, we went to the VirtualBox window and did the following procedure to change the button that allows you to escape the capture mode.

From the VirtualBox Window menu we went to: File –> Preferences –> Input and then clicked on the box next to HOST KEY COMBINATION and then typed the key we wanted to use.

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Send ALT+CTRL+Delete to QEMU virtual machine 1

Recently we wanted to start a Windows virtual machine from a physical hard disk using a Fedora w/ GNOME 3 host machine to change the domain password of a user.
To do so, we used QEMU, QEMU is a generic and open source machine emulator and virtualizer.

To perform the password change, we needed to sent the ALT+CTRL+Delete key combination to the virtual machine to access the system screen and then change the user password.
Pressing ALT+CTRL+Delete on the Fedora/GNOME 3 host machine, it popped up a prompt to shut down the host machine instead of sending the key combination to the active window of the VM. Apparently, we could not sent the key combination directly to the VM and had to find a way around it.

Solution:

We pressed ALT+CTRL+2 while the QEMU window was selected/active to switch to the QEMU terminal/monitor.
In the blank screen that appeared, we typed sendkey alt-ctrl-delete and pressed the Enter key.
This action sent to the virtual machine OS the key combination ALT+CTRL+Delete.
Finally, to switch back  to the guest screen we pressed ALT+CTRL+1.


Fedora: Start a Virtual Machine using a physical hard disk

Recently, we wanted to start a Virtual Machine running a Windows installation from a physical hard disk.

We could not find a way for GNOME Boxes to achieve this, so we installed qemu to do so.

We installed qemu using:

sudo dnf install qemu -y;

Configuring our command to start the Virtual Machine from the physical hard drive:

  • Our hard disk was identified on the physical machine as /dev/sda so we set the -hda parameter to that value.
  • Then we added the parameter -boot c to instruct the virtual machine to boot from the first hard disk.
  • The default guest start-up RAM size was 128 MiB, so we set the parameter -m to 4096 to give to the virtual machine 4GB of RAM.
  • Finally we added the -snapshot parameter which instructed the system to write to temporary files instead of the disk image files (all disk images are considered as read only).
    In this case, the raw disk image used are not written back. When sectors are written, they are written in a temporary file created in /tmp.
    You can however force the write back to the raw disk images by using the commit monitor command (or C-a s in the serial console).

In the end our command was as follows:

sudo qemu-kvm -snapshot -m 4096 -boot c -hda /dev/sda;


A couple of notes on moving a VirtualBox ‘.vdi’ disk image to a GNOME Boxes virtual machine

Recently we had a CentOS virtual machine on VirtualBox which we wanted to use in GNOME Boxes.
We copied the .vdi disk image and we used it to create a new virtual machine in Boxes.

Note A:

By doing this we realized that the system did not reuse the .vdi image.
It merely created a copy at ~/.local/share/gnome-boxes/images/ that was suitable for GNOME Boxes.
So, be sure to have enough space when doing an import like this.
You will need at least twice the space of the .vdi image to complete the migration.

Note B:

When the guest OS started the window manager crashed and it did not allow us to login.
We assumed that this issue occurred due to the VirtualBox Guest Additions that were installed on the guest OS.
As we could not login with the graphical interface, we could not verify this claim.

Fortunately, CentOS (and many other Linux distributions) allow you to switch to a console login using the key combination alt + ctrl + F3.
(There are more than one valid key combinations to do this. In some systems alt + ctrl + F4 is also valid or alt + ctrl + F1 etc).
We hoped that by trying to login via a console login, the Guest Additions would not start and the system would not crash, which luckily this was the case, and we managed to login through the console!

After we logged in, we had to remove the Guest additions. To do so we had to execute the uninstall script that was located at /opt/VBoxGuestAdditions-X.Y.Z/uninstall.sh
(X.Y.Z is the version number of the installed VirtualBox Guest Additions).

When the removal was complete, we executed sudo reboot to restart the system and unload any VirtualBox services that could be executing at the time.
Once the system completed the restart we were able to login properly from the GUI of GNOME and use our virtual machine properly.


Ubuntu 11.10 (Oneiric Ocelot): Cloning a KVM Virtual Machine

After properly installing and creating your first virtual machine, you might want to create a clone for some reason.

To do this we use the command virt-clone as follows:

sudo virt-clone --connect qemu:///system -o coeus -n phoebe -f /home/kvm/2KA.qcow2 -f /home/kvm/zK6.qcow2 --force

Where:

  • –connect is used to connect to the hypervisor of the virtual machine, here it is system
  • -o is the original virtual machine name (which is registered with the previous hypervisor)
  • -n is the name of the new virtual machine, the clone (this name will be used to register the clone to the hypervisor)
  • -f the location that the clone will use to store it’s virtual hard drives, can be used as many times as needed (in the above example coeus has two hard disks and that is why we need to provide two -f paramaters)
  • –force prevents interactive prompts and replies ‘yes’ to all yes/no questions

There is more directives that can be provided to the clone manager from which a very important one is the: –mac where you get to define the mac address of the new virtual machine (e.g –mac C0:FF:EE:11:00:11)