removed uneeded flags, used cmake specific method of gcc linking and added notes.

src/CMakeLists.txt

@@ -8,9 +8,14 @@ target_include_directories(${PROJECT_NAME} PUBLIC
     ${CMAKE_SOURCE_DIR}
 )
 
-target_link_libraries(${PROJECT_NAME}
+target_link_libraries(${PROJECT_NAME} PRIVATE 
+    gcc
 )
 
+
+# The `-ffunction-sections` and `-fdata-sections` need to be used 
+# in the compile and linker options otherwise it doesnt't
+# correctly remove the unused functions.
 target_compile_options(${PROJECT_NAME} PUBLIC
     -g
     -Os
@@ -22,14 +27,9 @@ target_compile_options(${PROJECT_NAME} PUBLIC
     -march=rv32ec
     -mabi=ilp32e
     -DCH32V003=1
-    -static-libgcc
-    -nostdlib
-    -lgcc
 )
 
 target_link_options(${PROJECT_NAME} PUBLIC
-    -g
-    -Os
     -flto
     -ffunction-sections
     -fdata-sections
@@ -37,9 +37,9 @@ target_link_options(${PROJECT_NAME} PUBLIC
     -msmall-data-limit=8
     -march=rv32ec
     -mabi=ilp32e
-    -DCH32V003=1
     -static-libgcc
     -nostdlib
+    -L${CMAKE_SOURCE_DIR}/src
     -Wl,--print-memory-usage
     -Wl,-Map=${PROJECT_NAME}.map
     -Wl,--gc-sections