ld -x -N -o netbsd -e start -Ttext 80030000 ${SYSTEM_OBJ} vers.o /usr/src/sys/lib/libkern/obj.pmax/libkern.a
   machdep.o(.text+0x34): undefined reference to `_end'
   machdep.o(.text+0x38): undefined reference to `_end'
   machdep.o(.text+0x44): undefined reference to `_edata'
   machdep.o(.text+0x48): undefined reference to `_edata'
   trap.o(.text+0x2494): undefined reference to `_edata'
   trap.o(.text+0x2498): undefined reference to `_edata'

These are magic symbols created by the linker.  The presence of
underscores tends to indicate that your C copmiler (GCC?) is adding
them.  I don't know why the symbols would be undefined, then, unless
the linker itself is not adding the underscores to the invented
symbols.

In GCC, you can do something like:

	extern char edata[] __asm__("edata"),
		    end[] __asm__("end");

to give explicit names to the symbols when the assembler code is
generated.