Bash completion for Kbuild

The kernel build system is written using Makefiles, and Bash completion for the make command is available through the bash-completion project.

However, the Makefiles for the kernel build are complex. The generic completion rules for the make command do not provide meaningful suggestions for the kernel build system, except for the options of the make command itself.

To enhance completion for various variables and targets, the kernel source includes its own completion script at scripts/bash-completion/make.

This script provides additional completions when working within the kernel tree. Outside the kernel tree, it defaults to the generic completion rules for the make command.

Prerequisites

The script relies on helper functions provided by bash-completion project. Please ensure it is installed on your system. On most distributions, you can install the bash-completion package through the standard package manager.

How to use

You can source the script directly:

$ source scripts/bash-completion/make

Or, you can copy it into the search path for Bash completion scripts. For example:

$ mkdir -p ~/.local/share/bash-completion/completions
$ cp scripts/bash-completion/make ~/.local/share/bash-completion/completions/

Details

The additional completion for Kbuild is enabled in the following cases:

  • You are in the root directory of the kernel source.

  • You are in the top-level build directory created by the O= option (checked via the source symlink pointing to the kernel source).

  • The -C make option specifies the kernel source or build directory.

  • The -f make option specifies a file in the kernel source or build directory.

If none of the above are met, it falls back to the generic completion rules.

The completion supports:

  • Commonly used targets, such as all, menuconfig, dtbs, etc.

  • Make (or environment) variables, such as ARCH, LLVM, etc.

  • Single-target builds (foo/bar/baz.o)

  • Configuration files (*_defconfig and *.config)

Some variables offer intelligent behavior. For instance, CROSS_COMPILE= followed by a TAB displays installed toolchains. The list of defconfig files shown depends on the value of the ARCH= variable.