allow additional extra_post_build_commands to be executed before any other post_build_commands

[rlezuo1]

Is your enhancement proposal related to a problem? Please describe. We need to include into resulting binaries timestamps and key-material.

• We could generate timestamp during the build, that however triggers compile & link whenever the timestamp changes. When using timestamps including seconds that is basically every time, so you can never double check that the build is "completed".

• When adding key-material you do not want to store it the repository at all or want different key-material for debug and release builds. Probably the development team does not even know the release key-material. Our non-zephyr build process patches the resulting ELF file (replacing development with release key-material).

Describe the solution you'd like

• hooks to modify the final ELF (i.e. zephyr.elf) with custom scripts
• BEFORE any other CONFIG_BUILDOUTPUT* (i.e. hex file includes the changes done to the ELF)

Describe alternatives you've considered There already is extra_post_build_commands, but it is run AFTER the CONFIG_BUILDOUTPUT* targets, i.e. the binary patching must be implemented for ELF, HEX and BIN in parallel.

Additional context commit ecdea1c30c implements custom hooks, but only AFTER,

[marc-hb]

Why not just turn on timestamps with a new Kconfig? Something like:

builder$ west build -- -DCONFIG_TIMESTAMPS=y

EDIT just for the record: https://docs.zephyrproject.org/latest/develop/west/extensions.html

[arbrauns]

I can't find a CONFIG_TIMESTAMPS anywhere in the zephyr tree, are you suggesting creating it in a custom Kconfig? If so, what should its effect be and how would it help with the problem at hand?

[marc-hb]

are you suggesting creating it in a custom Kconfig?

Yes

If so, what should its effect be

You sound like you already have a way to break build reproducibility and incremental builds. I'm merely suggesting you don't enable it by default but only when you need it.