Right, so as both 0-day and snowpatch tell me, this patch is wrong. It turns out that this: > $(obj)/serial.c: $(obj)/autoconf.h > + $(Q)cp $< $@ is identical to: cp arch/powerpc/boot/autoconf.h arch/powerpc/boot/serial.c
(Clearly my make mastery is inadequate.) Amusingly this which works for my 64e uImage but obviously not for anything that actually needs code from serial.c. Further analysis suggests that making with -j1 triggers the issue, but everything works with -j2 and above. That would make sense with the timeline of when I discovered the issue because I changed my build script to not build in parallel. Regards, Daniel