Build configuration

The tracked Buildroot configuration is kernel/external/configs/bados_x86_64_defconfig. The Buildroot external tree lives under kernel/external/; Docker Compose keeps generated output and downloads in named Docker volumes instead of the macOS workspace.

Buildroot options

The defconfig selects x86_64, Linux 6.12.27, Python 3, the local bdsh package, and a gzip-compressed CPIO root filesystem. It uses the QEMU x86_64 Linux configuration as a baseline, then adds kernel/external/board/bados/kernel.config as a kernel fragment.

To change Buildroot selections interactively:

make menuconfig
make save-osconfig

To edit kernel options, use make kernel-menuconfig and save required settings in the tracked fragment. make build reapplies the baseline and fragment before compiling, so an edit made only to the generated kernel config will not be retained.

Required kernel options

The image check verifies these are built into Linux:

• CONFIG_DEVTMPFS and CONFIG_DEVTMPFS_MOUNT, so device nodes are mounted before PID 1 starts.
• CONFIG_HW_RANDOM, CONFIG_HW_RANDOM_VIRTIO, CONFIG_VIRTIO, and CONFIG_VIRTIO_PCI, for QEMU’s virtual random-number device.

The fragment also enables framebuffer console support. Keep Buildroot’s QEMU kernel baseline: the fragment supplies BadOS requirements and is not a complete kernel configuration.

Build checks

make build runs the image check after the build. It verifies the required kernel options, executable /usr/bin/bdsh-init, target Python interpreter, Python zlib extension, and generated bzImage and rootfs.cpio.gz images before exporting the boot artifacts.