--prep-artifacts-for-testing causes relative BOARD_DIR path

[stgloorious]

Normally, BOARD_DIR contains a full, absolute path and is stored in CMakeCache.txt, but when using --prep-artifacts-for-testing, this path becomes relative. This fails the twister invocation if the application directory is separate from the zephyr directory. Specifying --board-root seems to have no effect.

To Reproduce

1. Run twister on any test suite with the --prep-artifacts-for-testing flag, e.g.,

west twister --prep-artifacts-for-testing -T tests/unit/crc

2. See that BOARD_DIR in twister-out/unit_testing_unit_testing/host/tests/unit/crc/utilities.crc/CMakeCache.txt is a relative path:

//Main board directory for board (unit_testing)
BOARD_DIR:PATH=subsys/testsuite/boards/unit_testing/unit_testing

Expected behavior
An absolute path, just when running west twister -T tests/unit/crc which shows

//Main board directory for board (unit_testing)
BOARD_DIR:PATH=/home/stefan/Downloads/zephyr_test/zephyr/subsys/testsuite/boards/unit_testing/unit_testing

in twister-out/unit_testing_unit_testing/host/tests/unit/crc/utilities.crc/CMakeCache.txt.

Impact
Because of this, I cannot run exported tests on a CI runner.

Environment:

• OS: Linux
• Toolchain: Zephyr SDK 0.17.0
• Zephyr: main (c0f76d9)

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[stgloorious]

To debug, I added

diff --git a/cmake/modules/boards.cmake b/cmake/modules/boards.cmake
index 3f086dca948..2ae1c0f0187 100644
--- a/cmake/modules/boards.cmake
+++ b/cmake/modules/boards.cmake
@@ -202,7 +202,10 @@ if(NOT "${ret_board}" STREQUAL "")
   set(multi_val  "DIR;REVISIONS;SOCS;QUALIFIERS")
   cmake_parse_arguments(LIST_BOARD "" "${single_val}" "${multi_val}" ${ret_board})
   list(GET LIST_BOARD_DIR 0 BOARD_DIR)
-  set(BOARD_DIR ${BOARD_DIR} CACHE PATH "Main board directory for board (${BOARD})" FORCE)
+  message(WARNING "Existing board_dir:${BOARD_DIR}")
+  set(BOARD_DIR "/foo/${BOARD_DIR}/bar" CACHE PATH "" FORCE)
+  set(BOARD_DIR "${BOARD_DIR}/foobar/" CACHE PATH "Main board directory for board (${BOARD})" FORCE)
+
   set(BOARD_DIRECTORIES ${LIST_BOARD_DIR} CACHE INTERNAL "List of board directories for board (${BOARD})" FORCE)
   foreach(dir ${BOARD_DIRECTORIES})
     set_property(DIRECTORY APPEND PROPERTY CMAKE_CONFIGURE_DEPENDS ${dir}/board.yml)

Which checks whether BOARD_DIR is read correctly from LIST_BOARD_DIR and saved to cache.

In the build.log, I can see that the BUILD_DIR CMake variable is actually the expected absolute path

CMake Warning at /home/stefan/projects/zephyr-app/zephyr/cmake/modules/boards.cmake:205 (message):
  Existing
  board_dir:/home/stefan/projects/zephyr-app/zephyr/boards/raspberrypi/rpi_pico2
Call Stack (most recent call first):
  /home/stefan/projects/zephyr-app/zephyr/cmake/modules/zephyr_default.cmake:133 (include)
  /home/stefan/projects/zephyr-app/zephyr/share/zephyr-package/cmake/ZephyrConfig.cmake:66 (include)
  /home/stefan/projects/zephyr-app/zephyr/share/zephyr-package/cmake/ZephyrConfig.cmake:92 (include_boilerplate)
  CMakeLists.txt:4 (find_package)

But for whatever reason, BUILD_DIR does not seem to be substituted properly in the following line, as CMakeCache.txt shows

//Main board directory for board (rpi_pico2)
BOARD_DIR:PATH=/fooboards/raspberrypi/rpi_pico2/bar/foobar

instead of the expected /foo/home/stefan/projects/zephyr-app/zephyr/boards/raspberrypi/rpi_pico2/bar/foobar.

I don't understand CMake well enough to have a clue what is going on here.

[nashif]

This is expected behaviour and part of what this option does. This is needed to be able to use the generated artifacts on other systems, so we sanitize the files to make them useable somewhere else. Using absolute paths here will not work in many scenarios (my $HOME on system A will not exist on system B under a different user...)

[stgloorious]

Thank you @nashif for your quick response.

I see your point. This was not clear to me because this seems to be the only path where this happens. All other paths in CMakeCache.txt remain absolute, regardless of the --prep-artifacts-for-testing option.

So this means I can only unpack twister-out in the zephyr directory (or the directory that is above the appropriate boards), as --board-root does not seem to have any effect. It seems counter-intuitive to me that I cannot package the artifacts on a build machine and copy them to the same location on an equivalent test runner (if I'm running twister from my workspace). Do you have any suggestions on how to resolve this?