Fixing #6, caused by arm GCC 10.2.0 now defaulting to -fno-common and not merging multiple definitions of the same variable across different files, a thing upon which uC/OS-III sources seem to rely on.

cross_arm.txt

@@ -14,6 +14,7 @@ openocd = '/usr/local/bin/openocd'
 
 [properties]
 c_args      = [
+               '-fcommon',
                '-mcpu=cortex-m4',           # Cortex-M4 CPU
                '-mthumb',                   # ARM Thumb2 ISA
                '-mfloat-abi=hard',          # Hard floating point support