[µTVM] Zephyr: Fix missing board-specific config file in build dir (a…

…pache#8230)

Currently board-specific config files (boards/*.conf) are not
copied from Zephyr project dir to the destination build dir, so
as a consequence the per board configs are not used when building
the runtime libraries, like libcommon. Hence, for instance, it's
currently not possible to set CONFIG_FPU per board since it only
takes effect when it's set in the generic 'prj.con' config file.

This commit fixes it by copying to the build dir (to each lib
dir) the proper .conf for the selected target board. For example,
if target 'qemu_x86' is selected 'qemu_x86.conf' is copied to
the boards/ dir inside the lib dirs, so Zephyr build system can
find it and combine it with configs found in the generic 'prj.conf'.

Signed-off-by: Gustavo Romero <gustavo.romero@linaro.org>

python/tvm/micro/contrib/zephyr.py

@@ -172,6 +172,17 @@ def library(self, output, sources, options=None):
             project_dir_conf = os.path.join(self._project_dir, "prj.conf")
             if os.path.exists(project_dir_conf):
                 shutil.copy(project_dir_conf, lib_prj_conf)
+
+            # Copy board-specific Zephyr config file from the project_dir to
+            # the build lib dir so board-specific configs can be found and used by
+            # Zephyr's build system in conjunction with the generic prj.conf configs.
+            board_conf = os.path.join("boards", self._board + ".conf")
+            project_dir_board_conf = os.path.join(self._project_dir, board_conf)
+            if os.path.exists(project_dir_board_conf):
+                os.mkdir(os.path.join(output, "boards"))
+                lib_dir_board_conf = os.path.join(output, board_conf)
+                shutil.copy(project_dir_board_conf, lib_dir_board_conf)
+
         else:
             with open(lib_prj_conf, "w") as prj_conf_f:
                 prj_conf_f.write("CONFIG_CPLUSPLUS=y\n")