Sub-projects like ULP are built as external CMake projects via
externalproject_add() and may use toolchains that are completely
different from the IDF target toolchain. For example, the ULP RISC-V
co-processor on an xtensa target (ESP32-S2/S3) uses
riscv32-esp-elf-gcc while the main project uses xtensa-esp-elf-gcc.
This causes problems in cmakev2:
1. __init_toolchain() in idf.cmake validates that CMAKE_TOOLCHAIN_FILE
matches IDF_TARGET and then overrides it. For sub-projects with
custom toolchains (passed via -DCMAKE_TOOLCHAIN_FILE from the
parent), this validation fails because the toolchain doesn't follow
the IDF naming convention (toolchain-<target>.cmake).
2. Several component project_include.cmake files use functions from
the IDF toolchain response file machinery (idf_toolchain_add_flags,
idf_toolchain_remove_flags, idf_toolchain_rerun_abi_detection) that
are not available in sub-projects with custom toolchains, or perform
validation that assumes the IDF target toolchain is in use.
Introduce IDF_CUSTOM_TOOLCHAIN, a CMake variable passed via -D from
the parent build to indicate that the toolchain was provided externally
and should not be resolved or validated by the IDF build system.
When IDF_CUSTOM_TOOLCHAIN is set:
- __init_toolchain() records the pre-set CMAKE_TOOLCHAIN_FILE and
skips IDF_TARGET-based resolution and validation.
- Component project_include.cmake files that manipulate IDF toolchain
flags (xtensa, esp_libc, esp_psram, soc) return early, as those
operations are not applicable to custom toolchains.
This is a generic mechanism usable by any sub-project that provides
its own toolchain (ULP, or any future sub-project with a non-IDF
toolchain).
Signed-off-by: Frantisek Hrbata <frantisek.hrbata@espressif.com>
In cmakev2, the project_include.cmake files for every component are
included. This means that even when working with RISC-V, the
project_include.cmake file for Xtensa is still included. Ensure that the
architecture is verified, and exit if it is not Xtensa.
Signed-off-by: Frantisek Hrbata <frantisek.hrbata@espressif.com>
By default, CMake message() commands prints to stderr.
IDEs like Eclipse show stderr output in red, which looks as if this is
some kind of error.
Use message(STATUS) instead.
