You can override the Linux kernel and associated packages using the option boot.kernelPackages. For instance, this selects the Linux 3.10 kernel: boot.kernelPackages = pkgs.linuxPackages_3_10; Note that this not only replaces the kernel, but also packages that are specific to the kernel version, such as the NVIDIA video drivers. This ensures that driver packages are consistent with the kernel. The default Linux kernel configuration should be fine for most users. You can see the configuration of your current kernel with the following command: cat /proc/config.gz | gunzip If you want to change the kernel configuration, you can use the packageOverrides feature (see ). For instance, to enable support for the kernel debugger KGDB: nixpkgs.config.packageOverrides = pkgs: { linux_3_4 = pkgs.linux_3_4.override { extraConfig = '' KGDB y ''; }; }; extraConfig takes a list of Linux kernel configuration options, one per line. The name of the option should not include the prefix CONFIG_. The option value is typically y, n or m (to build something as a kernel module). Kernel modules for hardware devices are generally loaded automatically by udev. You can force a module to be loaded via boot.kernelModules, e.g. boot.kernelModules = [ "fuse" "kvm-intel" "coretemp" ]; If the module is required early during the boot (e.g. to mount the root file system), you can use boot.initrd.extraKernelModules: boot.initrd.extraKernelModules = [ "cifs" ]; This causes the specified modules and their dependencies to be added to the initial ramdark. Kernel runtime parameters can be set through boot.kernel.sysctl, e.g. boot.kernel.sysctl."net.ipv4.tcp_keepalive_time" = 120; sets the kernel’s TCP keepalive time to 120 seconds. To see the available parameters, run sysctl -a.