1d7ee9ff09
The Nixpkgs documentation on the linux kernel builders focused on using and extending kernels that were already packaged, but never mentioned that it's possible to also build a kernel almost "from scratch". The NixOS documentation went a bit deeper on manual linux kernel configs, but that information wasn't particularly NixOS-specific. This commit consolidates the information related to building the kernel on Nixpkgs's documentation, while keeping any additional NixOS-specific information on NixOS's documentation. An additional README.md was created for contributor-facing documentation.
33 lines
1.8 KiB
Markdown
33 lines
1.8 KiB
Markdown
# How to add a new (major) version of the Linux kernel to Nixpkgs:
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1. Copy the old Nix expression (e.g., `linux-2.6.21.nix`) to the new one (e.g., `linux-2.6.22.nix`) and update it.
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2. Add the new kernel to the `kernels` attribute set in [`linux-kernels.nix`](./linux-kernels.nix) (e.g., create an attribute `kernel_2_6_22`).
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3. Update the kernel configuration. First unpack the kernel. Then for each supported platform (`i686`, `x86_64`, `uml`) do the following:
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1. Make a copy from the old config (e.g., `config-2.6.21-i686-smp`) to the new one (e.g., `config-2.6.22-i686-smp`).
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2. Copy the config file for this platform (e.g., `config-2.6.22-i686-smp`) to `.config` in the kernel source tree.
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3. Run `make oldconfig ARCH={i386,x86_64,um}` and answer all questions. (For the uml configuration, also add `SHELL=bash`.) Make sure to keep the configuration consistent between platforms (i.e., don’t enable some feature on `i686` and disable it on `x86_64`).
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4. If needed, you can also run `make menuconfig`:
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```ShellSession
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$ nix-env -f "<nixpkgs>" -iA ncurses
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$ export NIX_CFLAGS_LINK=-lncurses
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$ make menuconfig ARCH=arch
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```
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5. Copy `.config` over the new config file (e.g., `config-2.6.22-i686-smp`).
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4. Test building the kernel:
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```ShellSession
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nix-build -A linuxKernel.kernels.kernel_2_6_22
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```
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If it compiles, ship it! For extra credit, try booting NixOS with it.
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5. It may be that the new kernel requires updating the external kernel modules and kernel-dependent packages listed in the `linuxPackagesFor` function in `linux-kernels.nix` (such as the NVIDIA drivers, AUFS, etc.). If the updated packages aren’t backwards compatible with older kernels, you may need to keep the older versions around.
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