The `uk_binfmt_loader_args` accessors in glue/shim.c live behind `#if CONFIG_APPELFLOADER_ELF_BINFMT`, but binfmt.rs was compiled unconditionally, so with that option off the archive carried undefined references to C that was never built: appelfloader.o: in function `elfrs_binfmt_load': undefined reference to `elfrs_binfmt_pathname' The option depends on HAVE_VFS && LIBUKBINFMT && LIBPOSIX_PROCESS_MULTITHREADING, none of which this repository's own defconfigs enable -- it was only ever on in the bsdkrun Kraftfile, which is why every local build linked. Put the module behind a cargo feature and drive that feature from the same Kconfig symbol that guards the C side, so the two cannot disagree. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>