This test case has a large global array, which requires --near_data=none, and indeed the files that reference it have that option. However, another file (mpu_init.c) was compiled with --near_data=globals. Due to a bug in the compiler, all the --near_data options are merged at -O4 into a single --near_data that applies to all the recompiled files, and the merged value is "globals." With --near_data=globals, short pointers are used for the large global array, which can't work and causes a relocation-overflow error. The solution to the compiler bug is to stick with the original --near_data for each file. The workaround for this case is to make sure all files are compiled with --near_data=none, or else to use -O3 instead of -O4.