Linux Design

From the requirements we can derive the following design criteria.

Sources

As directly derived from the requirements the mainline sources of Linux must be used. However there can't be any restriction to a specify version. To be able to run any platform with the mainline sources of Linux the possibility of applying user patches during build has to be considered.

Repository

The user specification, such as configuration of Linux and potential user patches for the mainline sources should be stored together in a repository. Therefore each platform / version combination needs to have its own branch. E.g. if Linux version 1.0 and 1.2 should be build for platform A, two branches have to exist.

Cross Target Support

As Linux has to be build for different architectures cross target support needs to be considered.

Build Process

As mainline sources have to be used, those sources need to be retrieved somehow before the build process. Two possible options to retrieve the sources are:

• Yocto Project
• Buildroot
• The User has to provide sources within the repository
• The sources have to be downloaded before each build process
• Gentoo sources ebuild together with Gentoo has to be used

Build Steps

The build process must include the following steps.

1. Retrieve the build specifications from the repository
2. Retrieve kernel sources
3. Apply provided patches
4. (Cross-)Compile kernel for target architecture with kernel config provided by the specifications
5. Create two archives from the necessary files.
   • Files for the boot partition (kernel image, device tree blob)
   • Files for the root partition (e.g. modules)