Reproducible builds | |
=================== | |
In order to achieve reproducible builds, timestamps used in the U-Boot build | |
process have to be set to a fixed value. | |
This is done using the SOURCE_DATE_EPOCH environment variable which specifies | |
the number of seconds since 1970-01-01T00:00:00Z. | |
Example | |
------- | |
To build the sandbox with 2023-01-01T00:00:00Z as timestamp we can use: | |
.. code-block:: bash | |
make sandbox_defconfig | |
SOURCE_DATE_EPOCH=1672531200 make | |
This date is shown when we launch U-Boot: | |
.. code-block:: console | |
./u-boot -T | |
U-Boot 2023.01 (Jan 01 2023 - 00:00:00 +0000) | |
The same effect can be obtained with buildman using the `-r` flag. |