[xtensa] How to reference a toolchain file in a CMakeLists.txt ?

[williamtcdns]

When using the Xtensa Toolchain, and the environment variable XTENSA_CORE has been properly set, from the shell you can reach toolchain files using something like:
ls $(xt-run --show-config=config)/xtensa-elf/lib/sim-mc/mpu_table.c

If in a soc/cdns/*/CMakeLists.txt, we wish to use zephyr_library_sources_ifdef(CONFIG_XTENSA_MPU mpu_table.c) but want mpu_table.c to come from the expansion of $(xt-run --show-config=config)/xtensa-elf/lib/sim-mc/, how can it be accomplished ?

[williamtcdns]

@henrikbrixandersen @dcpleung @andyross @nashif @ceolin

[dcpleung]

That's more a CMake question as to how execute a program in .cmake files.

A hack would be to do a mpu_table.c file to #include the one under sim-mc, assuming sim-mc is in the search path.

Though, personally, I think it would be better to copy mpu_table.c into the SoC directory, assuming it is about how to setup the MPU table. We then don't have to hunt for the file if we need to look at it.

[williamtcdns]

Thanks @dcpleung , using #include <../lib/sim-mc/mpu_table.c> in soc/cdns/*/mpu_table.c works.

mpu_table.c is indeed about setting up the MPU table; the problem with copying it into the SoC directory is that, it is not the same for all configs, where a config is selected by the environment variable XTENSA_CORE.

We are trying to have a single SoC directory that can be used with any valid config set in XTENSA_CORE.