The kernel does not depend on external cpio tools. If you specify a
directory instead of a configuration file, the kernel's build infrastructure
creates a configuration file from that directory (usr/Makefile calls
-usr/gen_initramfs_list.sh), and proceeds to package up that directory
+usr/gen_initramfs.sh), and proceeds to package up that directory
using the config file (by feeding it to usr/gen_init_cpio, which is created
from usr/gen_init_cpio.c). The kernel's build-time cpio creation code is
entirely self-contained, and the kernel's boot-time extractor is also