When it first builds vmlinux (before linking with misc.o, etc) it says:
ld: waring: cannot find entry symbol _start; defaulting to 000fffe0
and when it tries to link to misc.o with
'ld -qmagic -Ttext 0xfe0 -o vmlinux head.o misc.o piggy.o'
I get
ld: warning: cannot find enrty symbol _start; defaulting to 00000fe0
misc.o(.text+0x1ebc): undefined reference to 'input_data'
misc.o(.text+0x1ec1): undefined reference to 'input_len'
misc.o(.text+0x1ed7): undefined reference to 'input_data'
and then make stops with an error.
-Corey