Installing a kernel patch on slackware

27 Nov 2024

A good rule in the slackware wiki about upgrading kernels is to never upgrade a running kernel. To do that one's /etc/slackpkg/blacklist file would contain kernel entries like so

kernel-generic.*
kernel-huge.*
kernel-modules.*
kernel-source

Now installing a newer kernel patch becomes a hands-on affair. Here's how we'd do it.

Download the kernel patch

$ mkdir /tmp/slack15
$ cd /tmp/slack15
$ lftp_repo https://slackware.in/slackware/slackware64-15.0/patches/packages/linux-5.15.161/

Here's the lftp_repo script file

#!/bin/sh

lftp -c "open $1 ; mirror -e -c"

This downloads the entire directory linux-5.15.161 from the above mirror. Feel free to substitute with your mirror and kernel of choice.

Here's how the local copy of the directory should look like

$ ls /tmp/slack15
./                                        kernel-huge-5.15.161-x86_64-1.txz
../                                       kernel-huge-5.15.161-x86_64-1.txz.asc
kernel-generic-5.15.161-x86_64-1.txt      kernel-modules-5.15.161-x86_64-1.txt
kernel-generic-5.15.161-x86_64-1.txz      kernel-modules-5.15.161-x86_64-1.txz
kernel-generic-5.15.161-x86_64-1.txz.asc  kernel-modules-5.15.161-x86_64-1.txz.asc
kernel-headers-5.15.161-x86-1.txt         kernel-source-5.15.161-noarch-1.txt
kernel-headers-5.15.161-x86-1.txz         kernel-source-5.15.161-noarch-1.txz
kernel-headers-5.15.161-x86-1.txz.asc     kernel-source-5.15.161-noarch-1.txz.asc
kernel-huge-5.15.161-x86_64-1.txt

Installing the patch

$ cd /tmp/slack15
# installpkg *.txz

Make sure you use installpkg. Do not use upgradepkg as it replaces the existing package.

Updating bootloader

First we generate a new initrd(init ramdisk)

# /usr/share/mkinitrd/mkinitrd_command_generator.sh -k 5.15.161

That should give us the command we'd need to generate the new initrd

# mkinitrd -c -k 5.15.161 -f ext4 -r /dev/lc230vg/root \
  -m redacted...:ext4 \
  -C /dev/sda3 -L -u \
  -o /boot/initrd-5.15.161.gz \
  -h /dev/lc230vg/swap

Please note the -o and -h. The -o tells mkinitrd not to overwrite /boot/initrd.gz and the -h is for specifying the swap partition for hibernating.

lilo (MBR)

If using plain lilo, update /etc/lilo.conf by adding a new image block

image = /boot/vmlinuz-generic-5.15.161
  initrd = /boot/initrd-5.15.161.gz
  root = /dev/lc230vg/root
  label = Linux-5.15.161
  read-only  # Partitions should be mounted read-only for checking

Then update lilo

# lilo -t
# lilo -v

elilo (UEFI)

If using a UEFI machine with elilo, copy over the kernel and initrd to /boot/efi

# cp /boot/initrd-5.15.161.gz /boot/efi/EFI/Slackware/.
# cp /boot/vmlinuz-generic-5.15.161 /boot/efi/EFI/Slackware/.

Update elilo, by adding a new image in /boot/efi/EFI/Slackware/elilo.conf

image=vmlinuz-generic-5.15.161
  label=5.15.161
  initrd=initrd-5.15.161.gz
  read-only
  append="root=/dev/mapper/lc230vg-root resume=/dev/mapper/lc230vg-swap vga=normal ro"

Side note: For UEFI machines we don't necessarily need to use the mkinitrd command. Install the kernel patch and then run a

# eliloconfig

This copies the kernel and initrd to the EFI System Partition and then updates elilo.

Reboot and enjoy the new kernel.

Happy Hacking & have a great day!