Attention

Qubes OS 4.2 has reached end of life - it is no longer supported and thus will no longer receive security updates, bug fixes, or new features. We recommend to perform an in-place upgrade or perform a clean installation of Qubes 4.3! The documentation of version 4.2 will also not receive any new updates, unless bug fixes. Its state is thus archived.

HVM troubleshooting

HVM pauses on boot, followed by kernel error

The HVM may pause on boot, showing a fixed cursor. After a while a series of warnings may be shown similar to this:

BUG: soft lockup - CPU#0 stuck for 23s! [systemd-udevd:244]

To fix this:

  1. Kill the HVM.

  2. Start the HVM

  3. Press “e” at the grub screen to edit the boot parameters

  4. Find the /vmlinuz line, and edit it to replace “rhgb” with “modprobe.blacklist=bochs_drm”

  5. Press “Ctrl-x” to start the HVM

If this solves the problem then you will want to make the change permanent:

  1. Edit the file /etc/default/grub.

  2. Find the line which starts:

    GRUB_CMDLINE_LINUX=

  3. Remove this text from that line:

    rhgb

  4. Add this text to that line:

    modprobe.blacklist=bochs_drm

  5. Run this command:

    $ grub2-mkconfig --output=/boot/grub2/grub.cfg

The HVM should now start normally.

Can’t start an OS in an HVM / “Probing EDD (edd=off to disable!… ok” message

If you see a screen popup with SeaBios and 4 lines, last one being Probing EDD (edd=off to disable!... ok, then enter the following command from a dom0 prompt:

$ qvm-prefs <HVMname> kernel ""

HVM crashes when booting from ISO

If your HVM crashes when trying to boot an ISO, first ensure that qvm-prefs <HVMname> kernel is empty, as shown above. If this doesn’t help, then disable memory balancing and set the minimum memory to 2GB.

You can disable memory-balancing in the settings, under the “Advanced” tab.

To give the VM a RAM of 2GB, open a terminal in dom0 and enter:

$ qvm-prefs <HVMname> memory 2000

Attached devices in Windows HVM stop working on suspend/resume

After the whole system gets suspended into S3 sleep and subsequently resumed, some attached devices may stop working. To know how to make the devices work, see Suspend/resume Troubleshooting.