cmake: Reuse llext flags for EDK

Some flags are common between in tree extensions and out of tree
supported by the EDK. Instead of duplicating those flags, the EDK reuses
the llext ones.

However, as the EDK has its own needs, two new lists,
`LLEXT_EDK_APPEND_FLAGS` and `LLEXT_EDK_REMOVE_FLAGS` are defined to
allow EDK to append or remove flags as needed.

Signed-off-by: Ederson de Souza <ederson.desouza@intel.com>

CMakeLists.txt

@@ -2064,6 +2064,17 @@ endif()
 
 # Extension Development Kit (EDK) generation.
 set(llext_edk_file ${PROJECT_BINARY_DIR}/${CONFIG_LLEXT_EDK_NAME}.tar.xz)
+
+# TODO maybe generate flags for C CXX ASM
+zephyr_get_compile_options_for_lang(C zephyr_flags)
+
+# Filter out non LLEXT and LLEXT_EDK flags - and add required ones
+llext_filter_zephyr_flags(LLEXT_REMOVE_FLAGS ${zephyr_flags} llext_edk_cflags)
+llext_filter_zephyr_flags(LLEXT_EDK_REMOVE_FLAGS ${llext_edk_cflags} llext_edk_cflags)
+
+list(APPEND llext_edk_cflags ${LLEXT_APPEND_FLAGS})
+list(APPEND llext_edk_cflags ${LLEXT_EDK_APPEND_FLAGS})
+
 add_custom_command(
     OUTPUT ${llext_edk_file}
     # Regenerate syscalls in case CONFIG_LLEXT_EDK_USERSPACE_ONLY
@@ -2085,7 +2096,7 @@ add_custom_command(
         -DINTERFACE_INCLUDE_DIRECTORIES="$<JOIN:$<TARGET_PROPERTY:zephyr_interface,INTERFACE_INCLUDE_DIRECTORIES>,:>"
         -Dllext_edk_file=${llext_edk_file}
         -DAUTOCONF_H=${AUTOCONF_H}
-        -DLLEXT_CFLAGS="${LLEXT_CFLAGS}"
+        -Dllext_cflags="${llext_edk_cflags}"
         -Dllext_edk_name=${CONFIG_LLEXT_EDK_NAME}
         -DWEST_TOPDIR=${WEST_TOPDIR}
         -DZEPHYR_BASE=${ZEPHYR_BASE}

cmake/compiler/gcc/target_arm.cmake

@@ -59,8 +59,11 @@ set(LLEXT_APPEND_FLAGS
   -mthumb
 )
 
-set(LLEXT_CFLAGS
-    -mlong-calls
-    -mthumb
+list(APPEND LLEXT_EDK_REMOVE_FLAGS
+    --sysroot=.*
+    -fmacro-prefix-map=.*
+    )
+
+list(APPEND LLEXT_EDK_APPEND_FLAGS
     -nodefaultlibs
-    -c)
+    )

cmake/llext-edk.cmake

@@ -19,7 +19,7 @@
 #   zephyr_interface target.
 # - AUTOCONF_H: Name of the autoconf.h file, used to generate the imacros flag.
 # - llext_edk_file: Output file name for the tarball.
-# - LLEXT_CFLAGS: Additional flags to be added to the generated flags.
+# - llext_cflags: Additional flags to be added to the generated flags.
 # - ZEPHYR_BASE: Path to the zephyr base directory.
 # - WEST_TOPDIR: Path to the west top directory.
 # - APPLICATION_SOURCE_DIR: Path to the application source directory.
@@ -44,9 +44,9 @@ set(autoconf_h_edk ${llext_edk_inc}/${AUTOCONF_H})
 cmake_path(RELATIVE_PATH AUTOCONF_H BASE_DIRECTORY ${PROJECT_BINARY_DIR} OUTPUT_VARIABLE autoconf_h_rel)
 
 list(APPEND base_flags_make
-    "${LLEXT_CFLAGS} -imacros\$(${install_dir_var})/include/zephyr/${autoconf_h_rel}")
+    "${llext_cflags} -imacros\$(${install_dir_var})/include/zephyr/${autoconf_h_rel}")
 list(APPEND base_flags_cmake
-    "${LLEXT_CFLAGS} -imacros\${CMAKE_CURRENT_LIST_DIR}/include/zephyr/${autoconf_h_rel}")
+    "${llext_cflags} -imacros\${CMAKE_CURRENT_LIST_DIR}/include/zephyr/${autoconf_h_rel}")
 
 file(MAKE_DIRECTORY ${llext_edk_inc})
 foreach(dir ${include_dirs})