How to boot custom built kernel

Help
1

Hi,

How can I get NixOS to boot a built kernel in a specified kernel source tree directory, for example /home/rah/my-modified-kernel/? I’ve searched the web, the NixOS wiki and these forums for information on how to do this, and asked on Matrix but to no avail.

Thanks,

rah

2

See this section of manual: Building a custom kernel. Wiki shows an example: Boot a kernel from a custom source, and use pkgs.fetchTarball(*.tar.gz) or builtin.path to fetch a local file.

src = pkgs.fetchTarball {
  name = "CUSTOMIZED_KERNEL";
  path = ./linux-kernel.tar.gz;
};
3

Please link to wiki.nixos.org instead, that other wiki is dead :slight_smile:

4

Namely Booting …

5

I’ve already seen these pages. The linked manual page describes building a kernel, presumably from nixpkgs, with a custom config. It’s not about installing and booting a kernel from a local kernel source tree.

This is about building a kernel from a tarball, not booting a kernel from a local source tree.

6

Set src to your local path, then.

7

To be clear, you mean a string containing the path of the directory?

8

No, I mean a path, not a string. A path does not have quotes around it.
https://nix.dev/manual/nix/2.24/language/syntax#path-literal

9

Still, this is about building the kernel, is it possible to install and boot an already-built kernel/modules/dtbs from a local directory? I don’t want to have to rebuild the entire kernel tree every time I make a change, which I understand is what Nix will do.

10

For posterity, from discussions on Matrix, the answer to this is “no”.