[Tools] Fix the abspath issue of Rtt_Root in building.py.
@@ -123,7 +123,7 @@ def PrepareBuilding(env, root_directory, has_libcpu=False, remove_components = [
global Rtt_Root
Env = env
- Rtt_Root = root_directory
+ Rtt_Root = os.path.abspath(root_directory)
# add compability with Keil MDK 4.6 which changes the directory of armcc.exe
if rtconfig.PLATFORM == 'armcc':
