| 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. |
