menuconfig

menuconfig for a 2.6.32 Linux kernel

make menuconfig is one of three tools (actually four starting with kernel 2.6.35; there is a new option: make nconfig that is similar to menuconfig) that can configure the Linux kernel source, a necessary early step needed to compile the source code. make menuconfig, with a convenient menu-driven user-interface, allows the user to choose the features of the Linux kernel (and other options) that will be compiled. It is normally invoked using the command make menuconfig, menuconfig is a target in the Linux kernel Makefile.

History

make menuconfig was not in the first version of Linux. The predecessor tool is a question-and-answer-based utility (make config, make oldconfig). A third tool for Linux configuration is make xconfig, which requires X.

Advantages over earlier versions

Despite being a simple design, make menuconfig offers considerable advantages to the question-and-answer-based configuration tool, the most notable being a basic search system and the ability to load and save files with filenames different from “.config”. make menuconfig gives the user an ability to navigate forwards or backwards directly between features, rather than using make config by pressing the enter (⏎) key up to 80 times to find a specific feature.

If the user is satisfied with a previous .config file, using make oldconfig uses this previous file to answer all questions that it can, only interactively presenting the new features. This is intended for a version upgrade, but may be appropriate at other times.

make menuconfig is a light load on system resources unlike make xconfig (uses Qt as of version 2.6.31.1, formerly Tk) or make gconfig, which utilizes GTK+. It's possible to ignore most of the features with make menuconfig, and doing so makes it more likely that one will configure an incomplete or oversized kernel. It's recommended to start with the .config file included with the Linux distribution, which makes it easier to configure a custom kernel.

Better than editing the .config by hand, make menuconfig easily shows the descriptions of each feature (?), and adds some (primitive in version 2.6.31.1) dependency checking. With make oldconfig, dependency checking can be done in one step, but requires the user to locate the features that were changed, by hand, to be sure that the needed ones are still enabled.

Practically, using both make menuconfig and make oldconfig, diff, (also cvs and a decent text editor) provides the most flexibility and most dependability. Configuring Linux is a significant labor, so users are strongly advised to make backups of it (i.e. cp /usr/src/linux*/.config ~/savemywork.config).

The help information is distributed throughout the kernel source tree in the various files called Kconfig.

Requsites/Dependencies

To use make menuconfig, the Linux kernel source is a requirement, a make tool, a C compiler, and the ncurses library.

Key Strokes

Main Key strokes

Key stroke	Meaning
?	Option description and tips/Help
Left/Right (⬌) Up/Down (⬍) PgUp/PgDn	Navigate through the kernel features and menuconfig commands.
Esc Esc	Exit menuconfig or cancel the command.
Enter (⏎)	Activate a command, or expand a branch.
y	Compile and include this feature inside of the kernel.
m	Compile this feature as a module, separate from the kernel.
n	Do not compile the feature.
/	Search configuration parameter.

Symbols

To the left of the features is the setting (y, M, or empty) enclosed in two punctuation marks.

Dependency information

Symbol	Meaning
< >	No dependencies.
[ ]	A dependency requires this to be compiled-in (y), or not compiled (n).
{ }	A dependency requires this to be a module (m) or compiled-in (y).
- -	A dependency requires this to be compiled-in (y).

Note that the supplied dependency information is primitive, it does not tell you the names of the depentant features.

Other symbols

Symbol	Meaning
--->	Use enter (⏎) to expand this branch as a new window.
(Experimental)	Less/Unstable code, beware.
(New)	An option not in your old version of Linux.

What next?

The user is encouraged to read the Linux README, since there are also many other targets. Each will configure the kernel, but with different features activated.

1. make menuconfig
2. Next build the compressed kernel and its modules, a long process. make.
3. Install using your favorite method such as make install, make modules_install.

See also

• GNU Compiler Collection
• Linus Torvalds
• Linux kernel
• ncurses
• Xconfig

References

• The make menuconfig tool itself.
• Linux From Scratch
• How to Build a Minimal Linux System
• Kernel Rebuild Guide
• Creating custom kernels with Debian's kernel-package system
• Cross compiling Linux on IBM System z
• How to roll your own Linux
• Building A Kernel The Traditional Way
• The Linux Kernel HOWTO

External links

• The Linux Kernel Archives
• Working with Kconfig - an article from the Real-Time Embedded blog