exec: 23: xz: not found
  HOSTCC  arch/x86/boot/compressed/mkpiggy
  MKPIGGY arch/x86/boot/compressed/piggy.S
arch/x86/boot/compressed/vmlinux.bin.xz: No such file or directory
  AS      arch/x86/boot/compressed/piggy.o
gcc: arch/x86/boot/compressed/piggy.S: No such file or directory
gcc: no input files
make[2]: *** [arch/x86/boot/compressed/piggy.o] Error 1
make[1]: *** [arch/x86/boot/compressed/vmlinux] Error 2
make: *** [bzImage] Error 2