Tom's Life Bits

What I learned was that if you plan to do significant and exploratory kernel modification, buildroot is probably not what you want. But if you need to make a small change (such as adding support for more serial ports), buildroot will probably suffice.

As was mentioned in the above URL, you will find it easiest to patch setup.c using quilt. I present it here in a more general and complete form:

1. Install quilt
2. cd into the kernel source directory (e.g., <buildroot>/project_build_avr32/<projectname>/linux-2.6.nn.nn)
3. Run “quilt new enable-two-usarts.patch”
4. Run “quilt edit arch/avr32/boards/<board_name>/setup.c” and make the changes you need.
5. Run “quilt refresh”
6. cp patches/enable-two-usarts.patch <buildroot>/target/device/Atmel/<board_config_name>/kernel-patches/linux-2.6.nn.nn-<patch_number>, where patch_number is any number like “01”.
7. cd to top of buildroot directory
8. Run make

To make this work for me, I had to first delete the <buildroot>/project_build_avr32/<projectname> directory, but I think that may have been because I had left it in a mess after previously trying to do this the wrong way.