[Question] How can I add kernel parametters in KDE Linux?

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1

Hi guys, since march 23 I decided to try out kde linux and I am really liking it, I was able to download all my apps with flatpaks and to set up my dev env with kapsule.

Now, I also do some virtualization and, while I was able to set up a container with systemd and most virt-host-validate qemu items passed, including cgroups, I wasn’t able to get iommu working. I tried the archwiki for systemd-boot but the files are not where they are supposed to be and I don’t know much about systemd-boot so I don’t know what to modify. On the other hands, I don’t know if the parametters would persist between updates.

I don’t know if there is an api or something to add kernel parametters or if that is supposed to added by the devs with an update but I need the following kernel parametters.

intel_iommu=on iommu=pt

If the devs are supposed to add this, I would really appreciate a workarround for the mid time untill they add it.

If this should have been reported on invent.kde.org, please let me know so I move it over. Thank you in advance.

2

Instructions for how to change the kernel flags temporarily can be found here: Recover from Boot Failures - KDE Community

There’s currently no way to permanently change them.

intel_iommu=on iommu=pt

I have some questions. Like:

  1. What do these flags do, and what’s the benefit of having them applied?
  2. Why can’t the functionality you’re looking for be used without them?
  3. Is there another way to change this system functionality without resorting to change the kernel command line?
  4. What would be the downsides of having them applied universally, for everyone?

Especially if there’s a valid reason to have these permanently applied, but only for some people and workflows, we’ll have to think harder about making it possible for people to permanently change the kernel command line.

3

There’s currently no way to permanently change them.

Ok… that is suprising. As kernel parameters are set by the boot loader, which AFAIK is installed parallel to the OS - and by that not part of the immutable image, I would have assumed that this is no more difficult than on any other linux: add boot parameters to the config (there is some overlay fs on top of /etc, right?), run grub-install, done.

Which makes me wonder: Why does this not work on KDE Linux?

4

In KDE Linux, kernel args are currently baked into each unified kernel image, and we haven’t yet built a way to permanently edit these.