To update decibel Linux, run the following in a terminal, as root:

> eix-sync
> emerge -uDN --keep-going --with-bdeps=y --backtrack=250 @system @world
> smart-live-rebuild
> emerge --depclean
> revdep-rebuild

Depending on what gets updated and how many updates there are, this could take a while. Plan on running updates when you are not using your system. Do not go without updating for more than 30 days. decibel Linux is basically Gentoo, and Gentoo is a rolling-release system. This means it is meant to be updated frequently. However, please observe the Gentoo etiquette of not running sync more than once per day. I personally update all my Gentoo machines once a month, on the first of the month. You can find whatever schedule works for you.

If there is an update to the kernel (rt-sources), run, as root:

> mount /dev/(boot_partition) /boot (Your boot partition would most likely be /dev/sda1, /dev/nvme0n1p1, etc.)
> ls /boot (If you've mounted the correct partition, you'll see files like System.map-6.1.28-rt-rt10-x86_64, initramfs-6.1.28-rt-rt10-x86_64.img and vmlinuz-6.1.28-rt-rt10-x86_64)
> eselect kernel list
> eselect kernel set x (Where x matches the number next to the new kernel version)
> genkernel --menuconfig all

When you see the kernel menu from –menuconfig, change the following items. Note that you need to tap escape twice to go back to a previous menu:

• General setup —>
  • Configure standard kernel features (expert users) ENABLE THIS ITEM (Scroll all the way down to find it)
  • Preemption model (Voluntary kernel preemption (Desktop)) CHANGE TO Fully Preemptible Kernel (Real-Time)
• Mitigations for speculative execution vulnerabilities DISABLE THIS ITEM (Note that this assumes you are using Gentoo Studio as a studio computer, and not a general purpose computer that’s always active online.)
• Power management and ACPI options —>
  • CPU frequency scaling —>
    • Default CPUFreq governor (schedutil) —> CHANGE TO performance

If there are any modules you need that aren’t set by default, now is the time to find them. For example, if you have a Mediatek wireless chip, you may need to find the Mediatek wireless drivers and enable them. If nothing is not working, don’t worry about it.

Escape out of menuconfig and genkernel will compile the kernel and modules. When that’s done, run:

> grub-mkconfig -o /boot/grub/grub.cfg (that's a lowercase letter o.)

Your new kernel will be used the next time you reboot.

If you are low on/out of space on the boot partition, you can manually delete older kernels and re-run grub-mkconfig. The three kernel files for each kernel version are initramfs-genkernel-x86_64-(version), kernel-genkernel-x86_64-(version) and System.map-genkernel-x86_64-(version). Pay attention and don’t delete the wrong kernel or you’ll have to re-run genkernel. As a general rule, keep at least the newest previous version to fall back on in case the latest version fails for any reason.