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tyder

Member

From: Oslo, Norway

Registered: 2016-12-19

Posts: 33  

Running virtual machines: Possible important difference Devuan/Debian

I used kvm a lot for system setup in Poor Man's Installs (PMI), but it hasn't worked well for the last 8 years - coinciding with the introduction of systemd in Debian.
Therefore, I was eager to try kvm with Devuan 6.1.1 for this purpose. The method is to use the squashfs base image, first version from the ISO, and then setup a new persistent image by running kvm with the same squashfs base image as the running version, but another persistent image, on another partition.
I add a new boot stanza in my good old legacy grub's menu lst, with a new persistence directory, and start this new version with kvm

The boot stanza for the booted, base version is

title Devuan 6.1.1 64 bits Xfce live sdb2 v0  persistence sdb3 
      root(hd0,0) 
      kernel  (hd0,0)/boot/dev611/vmlinuz boot=live config quiet splash initrd=(hd0,0)/boot/dev611/initrd.img  bootfrom=/dev/sdb2 live-media-path=dev611/live0 persistence persistence-path=dev611s/pers0 keyboard-layouts=no noautologin 
      initrd (hd0,0)/boot/dev611/initrd.img
 

The boot stanza for the setup version is almost identical, only specifying a different persistence directory

title Devuan 6.1.1 64 bits Xfce live sdb2 v0  persistence sdb5 
      root(hd0,0) 
      kernel  (hd0,0)/boot/dev611/vmlinuz boot=live config quiet splash initrd=(hd0,0)/boot/dev611/initrd.img  bootfrom=/dev/sdb2 live-media-path=dev611/live0 persistence persistence-path=dev611Xs/pers0 keyboard-layouts=no noautologin 
      initrd (hd0,0)/boot/dev611/initrd.img
 

Then I simply start the new version by having kvm run the pc's basic boot menu:

 sudo kvm -m 2048 /dev/sdb &

This may be viewed as kind of 'super-charged chroot', for the same squashfs is run in the pc and the vm, it is just merged with two different overlays.
In PMI, the base image is mounted read-only, so there is no problem with that. And the persistent images are mounted on different partitons, with no interference between them. There are of course lots of reasons for making different versions - for different users, with or without Docker, with or without R, to mention some of my own reasons. And setting them up in a vm is very practical, at least for me. Very primitive version handling as it may be, it works well for me with scripted package install lists.
When trying this with Debian 13.3.0 Lxqt, running under Devuan, I'm not able to make it work. I can start the vm with a base image from the boot menu, but it's not possible to make persistence work in any simple way. The persistence structure is exactly like the Devuan case, and booting natively with it, there are no problems.
Is this a systemd limitation? I suspect so.

Last edited by tyder (Today 13:45:29)