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diff --git a/content/gentoo-kernel-upgrade.md b/content/gentoo-kernel-upgrade.md new file mode 100644 index 0000000..203d6f2 --- /dev/null +++ b/content/gentoo-kernel-upgrade.md @@ -0,0 +1,132 @@ ++++ +title = "Gentoo kernel upgrade" ++++ + +## Preliminary steps + +Fetch the sources of the kernel that you want to install. + +```sh {class="cmd-root"} +emerge -uDUa --with-bdeps=y =sys-kernel/gentoo-sources-X.Y.Z +``` +You may also need to update @world set before updating the kernel. + +```sh {class="cmd-root"} +emerge -uDUa --with-bdeps=y @world +``` + +Using eselect, select the kernel version that you want to upgrade to. + +```sh {class="cmd-root"} +eselect kernel list +eselect kernel set X +``` + +Go to the directory containing kernel sources. + +```sh {class="cmd-root"} +cd /usr/src/linux +``` + +## Configuration + +Start by copying your `.config` from the old kernel sources. + +```sh {class="cmd-root"} +cp /usr/src/linux-A.B.C-gentoo/.config /usr/src/linux +``` + +Then, you will have to update the configuration file. The oldconfig command will interactively prompt you to insert values for the new options. + +```sh {class="cmd-root"} +make oldconfig +``` + +Alternatively, the olddefconfig command will automatically insert default values for the new options. + +```sh {class="cmd-root"} +make olddefconfig +``` + +To easily change more configuration options you can use the menuconfig command, which will start an interactive ncurses interface. + +```sh {class="cmd-root"} +make menuconfig +``` + +{{< note Warning >}} +Manually editing the `.config` file is highly discouraged. +{{< /note >}} + + +## Building + +Once you finished setting your configuration, you can build your kernel with make. +You can speed up the build process by using multiple make jobs (determine the number with nproc). + +```sh {class="cmd-root"} +make -jN +``` + +## Intel microcode addendum + +Firstly, install the microcode firmware and the tool to manage it. + +```sh {class="cmd-root"} +emerge sys-firmware/intel-microcode +``` + +Use the newly installed iucode_tool to get the processor signature and search a microcode bundle with a matching signature. + +```sh {class="cmd-root"} +iucode_tool -S +iucode_tool -S -l /lib/firmware/intel-ucode/* +``` + +Enable in the kernel configuration the microcode loading features. Then, add in the Firmware loading facility the microcode +bundle found before as a named firmware blob. + +After building the kernel, you can easily verify after the boot that the microcode is loaded with dmesg. + +```sh {class="cmd-root"} +dmesg | grep microcode +``` + +## Installation + +First of all, mount the boot partition, if it is not already mounted. + +```sh {class="cmd-root"} +mount /dev/XXX /boot +``` + +Then, you can install the new kernel and modules. + +```sh {class="cmd-root"} +make install +make modules_install +``` + +Update your bootloader configuration. If you are using GRUB, you can use grub-mkconfig. + +```sh {class="cmd-root"} +grub-mkconfig -o /boot/grub/grub.cfg +``` + +Some kernel modules may be installed by packages and live outside of the kernel source tree (e.g. Nvidia drivers), and need to be rebuilt. + +```sh {class="cmd-root"} +emerge @module-rebuild +``` + +Additionally, updating the firmware may be required by some drivers. + +```sh {class="cmd-root"} +emerge sys-kernel/linux-firmware +``` + +## References +- https://wiki.gentoo.org/wiki/Kernel +- https://wiki.gentoo.org/wiki/Kernel/Upgrade +- https://wiki.gentoo.org/wiki/Kernel/Removal +- https://wiki.gentoo.org/wiki/Intel_microcode |