I decided after a few problems that I would not upgrade my Debian machines from wheezy to jessie. jessie appears to be more oriented towards workstations, and the decision to set systemd as the only realistic boot loader in jessie caused concerns.

One of our technicians upgraded a Debian Wheezy Xen DOM0 in early fall of 2017, and while it rebooted, it could no longer run hardware virtualized machines (hvm's). I was called in to solve the issue and failed.

Finally, after deciding the only solution was a complete reinstall, I decided to test out the devuan distribution (http://devuan.org/), which was created to develop a systemd free alternative to Debian. Within an hour, the system was up and running.

Following are my notes on how this was accomplished. Most were taken from https://git.devuan.org/dev1fanboy/Upgrade-Install-Devuan/wikis/Upgrade-to-Devuan

1. update the server as best you can (I often bypass this)
2. Modify /etc/apt/sources.list to reflect devuan's repositories
   1. Set up the devuan keyring
3. perform an update, then a dist-upgrade
4. install qemu-system-x86
5. edit all hvm domu configuration files to clean them up

Note that the step, install qemu-system-x86 is possibly the only fix that was necessary. I could still be running Debian Wheezy, probably. However, by upgrading to devuan, I get new kernel's and packages, and it was only after the upgrade I got useful error messages leading me to install this.

Basically, do as you normally do. The system will be broken after this

apt-get update && apt-get upgrade

Edit /etc/apt/sources.list and remove all entries pointing to debian, then add the following lines (I remove them by commenting them out)

deb http://auto.mirror.devuan.org/merged jessie main
deb http://auto.mirror.devuan.org/merged jessie-updates main
deb http://auto.mirror.devuan.org/merged jessie-security main

In most cases, these should be the only lines in sources.list

Now, import the devuan keyring

apt-get update && apt-get install devuan-keyring -y --allow-unauthenticated

apt-get update -y
apt-get dist-upgrade

The -y is needed or it will complain about the keyring the first time.

reboot the system

reboot

Appearently, someone has broken the qemu system into pieces in this upgrade. Good idea; if you are only going to use paravirtualized domu's, there is no need for it. But, if you are using hardware virtualized, this is what makes it work.

apt-get install qemu-system-x86

The configuration options for hvm's has changed, with many not being used. In /etc/xen, there is a sample for hvm's which will help a lot, however the following is a quick and dirty list.

• replace device_model line with device_model_version='qemu-xen'
• comment out the line beginning with kernel if you have it
• set builder=“hvm”

Again, read the sample conf, but basically, remove anything not needed.

Just a note on how to upgrade jessie to ascii (devuan)

deb http://deb.devuan.org/merged ascii main
deb http://deb.devuan.org/merged ascii-updates main
deb http://deb.devuan.org/merged ascii-security main
deb http://deb.devuan.org/merged ascii-backports main

apt-get upgrade devuan-keyring
apt-get update
apt-get dist-upgrade