If you try to extract a initrd and only file some uncompressed cpio:
$ file /boot/initrd.img-3.14-1-amd64 /boot/initrd.img-3.14-1-amd64: ASCII cpio archive (SVR4 with no CRC) $ cat /boot/initrd.img-3.14-1-amd64 | cpio -t kernel kernel/x86 kernel/x86/microcode kernel/x86/microcode/GenuineIntel.