kumquat-buildroot/docs/manual/adding-board-support.txt

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[[adding-board-support]]
== Adding support for a particular board

Buildroot contains basic configurations for several publicly available
hardware boards, so that users of such a board can easily build a system
that is known to work. You are welcome to add support for other boards
to Buildroot too.

To do so, you need to create a normal Buildroot configuration that
builds a basic system for the hardware: (internal) toolchain, kernel,
bootloader, filesystem and a simple BusyBox-only userspace. No specific
package should be selected: the configuration should be as minimal as
possible, and should only build a working basic BusyBox system for the
target platform. You can of course use more complicated configurations
for your internal projects, but the Buildroot project will only
integrate basic board configurations. This is because package
selections are highly application-specific.

Once you have a known working configuration, run +make
savedefconfig+. This will generate a minimal +defconfig+ file at the
root of the Buildroot source tree. Move this file into the +configs/+
directory, and rename it +<boardname>_defconfig+. If the configuration
is a bit more complicated, it is nice to manually reformat it and
separate it into sections, with a comment before each section. Typical
sections are _Architecture_, _Toolchain options_ (typically just linux
headers version), _Firmware_, _Bootloader_, _Kernel_, and _Filesystem_.

Always use fixed versions or commit hashes for the different
components, not the "latest" version. For example, set
+BR2_LINUX_KERNEL_CUSTOM_VERSION=y+ and
+BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE+ to the kernel version you tested
with.

It is recommended to use as much as possible upstream versions of the
Linux kernel and bootloaders, and to use as much as possible default
kernel and bootloader configurations. If they are incorrect for your
board, or no default exists, we encourage you to send fixes to the
corresponding upstream projects.

However, in the mean time, you may want to store kernel or bootloader
configuration or patches specific to your target platform. To do so,
create a directory +board/<manufacturer>+ and a subdirectory
+board/<manufacturer>/<boardname>+. You can then store your patches
and configurations in these directories, and reference them from the main
Buildroot configuration. Refer to xref:customize[] for more details.