Handbook:Parts/Installation/Kernel/Dist-Kernel/en

Alternative: Using distribution kernels
Distribution Kernels are ebuilds that cover the complete process of unpacking, configuring, compiling, and installing the kernel. The primary advantage of this method is that the kernels are upgraded to new versions as part of @world upgrade without a need for manual action. Distribution kernels default to a configuration supporting the majority of hardware but they can be customized via.

There are other methods available to customize the kernel config such as config snippets.

Installing correct installkernel
Before using the distribution kernels, please verify that the correct installkernel package for the system is installed. When using systemd-boot (formerly gummiboot), install:

When using a traditional layout (e.g. GRUB, LILO, etc.), the gentoo variant should be installed by default. If in doubt:

Installing a distribution kernel
To build a kernel with Gentoo patches from source, type:

System administrators who want to avoid compiling the kernel sources locally can instead use precompiled kernel images:

Upgrading and cleaning up
Once the kernel is installed, the package manager will automatically upgrade it to newer versions. The previous versions will be kept until the package manager is requested to clean up stale packages. Please remember to periodically run:

to save space. Alternatively, to specifically clean up old kernel versions:

Post-install/upgrade tasks
Distribution kernels are now capable of rebuilding kernel modules installed by other packages. provides  which controls a subslot dependency on.

Enabling this on packages like and  allows them to automatically be rebuilt against the new kernel and re-generate the initramfs if applicable accordingly!

Manually rebuilding the initramfs
If required, manually trigger such rebuilds by, after a kernel upgrade, executing:

If any of these modules (e.g. ZFS) are needed at early boot, rebuild the initramfs afterward: