cmake: Toolchain abstraction: introduce toolchain_ld_baremetal()

The intent of toolchain_ld_baremetal() is to collect the flags belonging
to non-hosted (i.e. POSIX-based) targets.

No functional change expected.

This is motivated by the wish to abstract Zephyr's usage of toolchains,
permitting non-intrusive porting to other (commercial) toolchains.

Signed-off-by: Mark Ruvald Pedersen <mped@oticon.com>

CMakeLists.txt

@@ -225,11 +225,8 @@ zephyr_compile_options(
 toolchain_ld_base()
 
 if(NOT CONFIG_NATIVE_APPLICATION)
-zephyr_ld_options(
-  -nostdlib
-  -static
-  -no-pie
-)
+  # @Intent: Set linker specific flags for bare metal target
+  toolchain_ld_baremetal()
 endif()
 
 if(CONFIG_LIB_CPLUSPLUS)
@@ -379,13 +376,6 @@ if(CONFIG_USERSPACE)
   endif()
 endif()
 
-if(NOT CONFIG_NATIVE_APPLICATION)
-zephyr_ld_options(
-  ${LINKERFLAGPREFIX},-X
-  ${LINKERFLAGPREFIX},-N
-  )
-endif()
-
 zephyr_ld_options(
   ${LINKERFLAGPREFIX},--gc-sections
   ${LINKERFLAGPREFIX},--build-id=none

cmake/linker/ld/target.cmake

@@ -6,3 +6,4 @@ set_ifndef(LINKERFLAGPREFIX -Wl)
 
 # Load toolchain_ld-family macros
 include(${ZEPHYR_BASE}/cmake/linker/${LINKER}/target_base.cmake)
+include(${ZEPHYR_BASE}/cmake/linker/${LINKER}/target_baremetal.cmake)

cmake/linker/ld/target_baremetal.cmake

@@ -0,0 +1,15 @@
+# SPDX-License-Identifier: Apache-2.0
+
+# See root CMakeLists.txt for description and expectations of these macros
+
+macro(toolchain_ld_baremetal)
+
+  zephyr_ld_options(
+    -nostdlib
+    -static
+    -no-pie
+    ${LINKERFLAGPREFIX},-X
+    ${LINKERFLAGPREFIX},-N
+  )
+
+endmacro()