Configure L4Re and the Microkernel

Both L4Re and the L4Re Microkernel use Linux’s Kconfig system for configuration. If you have worked with Linux’s configuration system before this should feel familiar to you.

Configuration using the older ncurses interface

Once you’ve created a build directory and navigated into it. You can run the following command to configure your build:

make menuconfig

In this interface you navigate around using the arrow keys. If you want to search for an option you can type / to search.

Entries with a ---> at the end are sub menus which can be entered using the Enter key.

Entries that begin with a [ ] or [*] are boolean options which can be toggled using the space bar.

Entries that begin with a value in parenthesis are options that require an integer or string value. These can also bne adjusted by pressing the Enter key.

More information about a particular option can be accessed using the ? key.

Configuration using the newer ncurses interface

There is a newer ncurses interface which can be started as follows:

make nconfig

It behaves similarly to the older ncurses interface.

Configuration using the GTK interface

To start the GTK GUI for configuration, you can run the following command:

make gconfig

A window will popup that can be navigated using the mouse cursor.

Configuration using the GTK interface

To start the Qt GUI for configuration, you can run the following command:

make xconfig

A window will popup that can be navigated using the mouse cursor.

Reconfiguration after updating the sources

When updating your sources new options might have been introduced in the meantime. After updating your sources you can run the following command and the build system will show any newly introduced options:

make oldconfig

Default configs (defconfig)

Kconfig can save a separate configuration file with all the options removed that have their default values set, commonly known as a defconfig. This is useful if you want to reuse your configuration in the future, but want to have any changed defaults as well. To generate such a defconfig run the following command:

make savedefconfig

This command will generate a file called defconfig in the root of your build directory.

When you want to reuse such a defconfig in the future, you can copy its contents to the corresponding config file (for L4Re this file is called .kconfig, for the L4Re microkernel this file is called globalconfig.out)

After copying its contents, you should run the following command to apply all the current defaults:

make olddefconfig