Downgrading your kernel
Why downgrade your kernel? Isn’t the bleeding edge of Arch always the best? /s
Sometimes there are bugs in computer programs (I know right, how impossible to believe). For the most part Linux kernel issues haven’t affected me in a while. However over the weekend I updated to 5.12.13 and I ran into some weird issues with my video cards. They seemed to be running full blast while doing nothing… Turns out there was a regression in the 5.12.13 release that caused this. Bug in question can be found here.
So it was time to downgrade.
Options
There are a several options to downgrading in Arch
- Arch Linux Archives repositories
- downgrade or downgrader-git from AUR’s
- Arch Rollback Machine
- pacman
I’ll just go over the details of the easiest one (this is assuming that you don’t vehemently clear your paccache with paccache -r every couple minutes) which is just using pacman, which you likely use to install packages anyways so you should already know how to use this. But you may not be aware of how to actually go and re-install old packages (or in this case kernels).
The Downgrade
OK so lets go take a peek at what downgrades we have available. We’ll want to go check the /var/cache/pacman/pkg directory to see whats available.
cd /var/cache/pacman/pkg && ls -al |grep linux | grep -v sig
rw-r--r-- 1 root root 94 MiB Thu Jun 10 14:35:18 2021 linux-5.12.10.arch1-1-x86_64.pkg.tar.zst
rw-r--r-- 1 root root 94 MiB Wed Jun 16 19:14:38 2021 linux-5.12.11.arch1-1-x86_64.pkg.tar.zst
rw-r--r-- 1 root root 94 MiB Fri Jun 18 20:19:31 2021 linux-5.12.12.arch1-1-x86_64.pkg.tar.zst
rw-r--r-- 1 root root 95 MiB Wed Jun 23 14:16:19 2021 linux-5.12.13.arch1-1-x86_64.pkg.tar.zst
rw-r--r-- 1 root root 95 MiB Fri Jun 25 20:49:37 2021 linux-5.12.13.arch1-2-x86_64.pkg.tar.zst
rw-r--r-- 1 root root 1 MiB Sun May 16 23:06:40 2021 linux-api-headers-5.12.3-1-any.pkg.tar.zst
rw-r--r-- 1 root root 167 MiB Sat May 15 03:32:38 2021 linux-firmware-20210511.7685cf4-1-any.pkg.tar.zst
rw-r--r-- 1 root root 98 MiB Thu Jun 10 14:35:17 2021 linux-zen-5.12.10.zen1-1-x86_64.pkg.tar.zst
rw-r--r-- 1 root root 98 MiB Wed Jun 16 19:14:38 2021 linux-zen-5.12.11.zen1-1-x86_64.pkg.tar.zst
rw-r--r-- 1 root root 98 MiB Fri Jun 18 20:19:31 2021 linux-zen-5.12.12.zen1-1-x86_64.pkg.tar.zst
rw-r--r-- 1 root root 98 MiB Wed Jun 23 14:16:19 2021 linux-zen-5.12.13.zen1-1-x86_64.pkg.tar.zst
rw-r--r-- 1 root root 98 MiB Fri Jun 25 20:49:38 2021 linux-zen-5.12.13.zen1-2-x86_64.pkg.tar.zst
rw-r--r-- 1 root root 24 MiB Thu Jun 10 14:35:18 2021 linux-zen-headers-5.12.10.zen1-1-x86_64.pkg.tar.zst
rw-r--r-- 1 root root 24 MiB Wed Jun 16 19:14:39 2021 linux-zen-headers-5.12.11.zen1-1-x86_64.pkg.tar.zst
rw-r--r-- 1 root root 24 MiB Fri Jun 18 20:19:32 2021 linux-zen-headers-5.12.12.zen1-1-x86_64.pkg.tar.zst
rw-r--r-- 1 root root 24 MiB Wed Jun 23 14:16:20 2021 linux-zen-headers-5.12.13.zen1-1-x86_64.pkg.tar.zst
rw-r--r-- 1 root root 24 MiB Fri Jun 25 20:49:39 2021 linux-zen-headers-5.12.13.zen1-2-x86_64.pkg.tar.zst
Alright so it looks like we still have a few options here for kernel’s to roll back to stored locally. Why go to the Internet when you don’t have to.
So there were problems with the ~5.12.13~ kernel’s. So I’m just going to roll-back to the 5.12.12 release. You can do the same if needed with the following command.
sudo pacman -U linux-5.12.12.arch1-1-x86_64.pkg.tar.zst linux-zen-5.12.12.zen1-1-x86_64.pkg.tar.zst linux-zen-headers-5.12.12.zen1-1-x86_64.pkg.tar.zst
sudo grub-mkconfig -o /boot/grub/grub.cfg
That’s it. You’ll be prompted saying that your downgrading some packages. The second line is not always required, unless you’ve changed something recently with your grub configuration.
Reboot
Profit, or in this case, make my video cards not run at 100% all the time.