1Reproducible builds
2===================
3
4In order to achieve reproducible builds, timestamps used in the U-Boot build
5process have to be set to a fixed value.
6
7This is done using the SOURCE_DATE_EPOCH environment variable which specifies
8the number of seconds since 1970-01-01T00:00:00Z.
9
10Example
11-------
12
13To build the sandbox with 2023-01-01T00:00:00Z as timestamp we can use:
14
15.. code-block:: bash
16
17    make sandbox_defconfig
18    SOURCE_DATE_EPOCH=1672531200 make
19
20This date is shown when we launch U-Boot:
21
22.. code-block:: console
23
24    ./u-boot -T
25    U-Boot 2023.01 (Jan 01 2023 - 00:00:00 +0000)
26
27The same effect can be obtained with buildman using the `-r` flag.
28