Just small hints that can do it: * try to add `CC_EXTRA_OPTS="-DMY_CUSTOM_FLAG"` to `make cfg ...` command. * changing `Makefile.defs` after `make cfg ...` makes the `make Q=0` run internally another simple `make cfg`
As Henning said, in case of still having issue, open an issue for a maintained branch to try to get some more help.