kconfq

A portable way to query kernel configuration on a live system (/boot/config-* or /proc/config.gz).

It provides:

• A CLI (kconfq)
• A C-API library (libkconfq.so, kconfq.h, kconfq.pc)
• A Rust crate

Usage (as a CLI)

Instaling via cargo:

cargo install kconfq

Instaling via Nix:

nix profile install github:synalice/kconfq

Running without installation:

nix run github:synalice/kconfq

Usage as a C-API library

Even though the core of the library is written in Rust, it can be compiled as a cdynlib with C ABI.

The project will generate:

• libkconfq.so
• kconfq.h
• kconfq.pc

All of this makes it possible to use library as any normal C dependency. Here is an example of how this would look like in Meson

kconfq = dependency('kconfq')

Example

You can see the example of how to use the C-API in the examples/libkconfq/ directory.

To build and run the example, run the following commands:

cd examples/libkconfq/
nix develop
meson setup builddir/
meson compile -C builddir/
./builddir/example

Building from source

To build and install library from source you have to use cargo-c.

cargo cbuild --release --destdir=${D} --prefix=/usr --libdir=/usr/lib64
cargo ctest
cargo cinstall --release --destdir=${D} --prefix=/usr --libdir=/usr/lib64

Using inside the flake.nix

This is how you would add this library to your flake.nix and then reference it inside your derivation's buildInputs

{
  inputs = {
    nixpkgs.url = "github:nixos/nixpkgs/nixos-25.11";
    flake-utils.url = "github:numtide/flake-utils";
    kconfq = {
      url = "github:synalice/kconfq";
      inputs.nixpkgs.follows = "nixpkgs";
    };
  };

  outputs = { self, nixpkgs, flake-utils, kconfq }:
    flake-utils.lib.eachDefaultSystem (
      system:
      let
        pkgs = nixpkgs.legacyPackages.${system};
      in
      {
        packages.default = pkgs.clangStdenv.mkDerivation {
          pname = "example";
          version = "0.1.0";
          src = ./.;

          buildInputs = [ kconfq.packages.${system}.libkconfq ];
        };
      }
    );
}

Cross-compilation

The project was created with easy cross-compilation in mind.

Here is how you can cross-compile libkconfq for aarch64-unknown-linux-gnu using Nix

./scripts/cross-compile.sh aarch64-multiplatform ./nix/libkconfq.nix out

Tip

To cross-compile for different host architectures, replace aarch64-multiplatform with riscv64 or something else. Read more here.

TODO

• Add tests.

License

This project is under the MIT license.