To build busybox for TS-75XX/TS-4500 series, you must use for best compatibility: make EXTRA_LDFLAGS="-Wl,--rpath,/slib -Wl,-dynamic-linker,/slib/ld-uClibc.so.0" When finished building, copy busybox binary to /bin/ on the initrd partition, replacing what was there before. For any busybox programs like 'chat', simply create a symlink: ln -s /bin/busybox /bin/chat