Commit 70e38eea authored by Heinrich Schuchardt's avatar Heinrich Schuchardt 💬 Committed by Tom Rini

doc: describe building with GCC

Provide a description of the U-Boot build process with GCC in the HTML
Signed-off-by: Heinrich Schuchardt's avatarHeinrich Schuchardt <>
parent 2974ba4f
Building with GCC
For building U-Boot you need a GCC compiler for your host platform. If you
are not building on the target platform you further need a GCC cross compiler.
Debian based
On Debian based systems the cross compiler packages are named
You could install GCC and the GCC cross compiler for the ARMv8 architecture with
.. code-block:: bash
sudo apt-get gcc gcc-aarch64-linux-gnu
Depending on the build targets further packages maybe needed
.. code-block:: bash
sudo apt-get install bc bison build-essential coccinelle \
device-tree-compiler dfu-util efitools flex gdisk liblz4-tool \
libguestfs-tools libncurses-dev libpython3-dev libsdl2-dev libssl-dev \
lzma-alone openssl python3 python3-coverage python3-pyelftools \
python3-pytest python3-sphinxcontrib.apidoc python3-sphinx-rtd-theme swig
For some boards you have to build prerequisite files before you can build
U-Boot, e.g. for the some boards you will need to build the ARM Trusted Firmware
beforehand. Please, refer to the board specific documentation
Directory configs/ contains the template configuration files for the maintained
boards following the naming scheme::
<board name>_defconfig
These files have been stripped of default settings. So you cannot use them
directly. Instead their name serves as a make target to generate the actual
configuration file .config. For instance the configuration template for the
Odroid C2 board is called odroid-c2_defconfig. The corresponding .config file
is generated by
.. code-block:: bash
make odroid-c2_defconfig
You can adjust the configuration using
.. code-block:: bash
make menuconfig
When cross compiling you will have to specify the prefix of the cross-compiler.
You can either specify the value of the CROSS_COMPILE variable on the make
command line or export it beforehand.
.. code-block:: bash
CROSS_COMPILE=<compiler-prefix> make
Assuming cross compiling on Debian for ARMv8 this would be
.. code-block:: bash
CROSS_COMPILE=aarch64-linux-gnu- make
Build parameters
A list of available parameters for the make command can be obtained via
.. code-block:: bash
make help
You can speed up compilation by parallelization using the -j parameter, e.g.
.. code-block:: bash
CROSS_COMPILE=aarch64-linux-gnu- make -j$(nproc)
Further important build parameters are
* O=<dir> - generate all output files in directory <dir>, including .config
* V=1 - verbose build
Other build targets
A list of all make targets can be obtained via
.. code-block:: bash
make help
Important ones are
* clean - remove most generated files but keep the configuration
* mrproper - remove all generated files + config + various backup files
The process for installing U-Boot on the target device is device specific.
Please, refer to the board specific documentation :doc:`../board/index`.
......@@ -7,5 +7,6 @@ Build U-Boot
:maxdepth: 2
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