Features/Kconfig (GSoC 2013)

UPDATE: The kconfig language was integrated in QEMU 4.0.

Summary

The aim of this Google Summer of Code 2013 project is to bring the Linux kernel's Kconfig facility to Qemu, making it much easier to configure at build-time.

An example target configuration

An example configuration for the i386 target

Owner

• Name: Ákos Kovács
• Email: akoskovacs@gmx.com

Implementation

Main topics

1. Importing kconfig-frontends to Qemu (at scripts/kconfig)
2. New syntactical structures in the Kconfig files (with writing the actual Kconfig files)
3. Integrating kconfig to the existing build infrastructure

Progress

At the time, the first and the second topic is in progress. This means, that the kconfig-frontends can be built from the top-level directory (with 'make menuconfig/xconfig/gconfig/...') and has a new syntactical structure.

This will enable the user to manage all targets from one root Kconfig file. The current syntax consist a 'symbol' token and the actual symbol itself, which can be written in this way:

   config TEST 
       prompt "A foo-bar feature"
       symbol TARGET_FOO
       default n

However, this is not a fixed syntax and there could be other ways.

Another challenge, is to get the currently supported devices and boards for each target and to transform them to usable Kconfig files. Qemu has already have a feature, which can dump the devices at the runtime. This tree can be gathered with the info qtree command in the Qemu monitor. The board list can be gathered in a similar way, with -M ? command line options. If everything works fine, we just need to get name of the C files, where these devices implemented.

However some targets are not able to provide the device tree without a valid image. Therefore, a better way could be a hack in the Qemu's source code. A call to the printf() in the right place can make miracles. This means, we can get the full lists of devices and boards with a call in the target_register_internal() and the qemu_register_machine(). Some macros with these names can also make this hack more effective, so we can get list with the associated C files (using the __FILE__).

Code repository

Current code repository is available at github. git clone git://github.com/akoskovacs/qemu.git