[root@rpi1-frank skeldev]# make -C /usr/src/kernels/3.12.26-1.20140808git4ab8abb.rpfr20.armv6hl.bcm2708/
make: Entering directory `/usr/src/kernels/3.12.26-1.20140808git4ab8abb.rpfr20.armv6hl.bcm2708'
  CHK     include/config/kernel.release
  CHK     include/generated/uapi/linux/version.h
  CHK     include/generated/utsrelease.h
make[1]: *** No rule to make target `arch/arm/tools/gen-mach-types', needed by `include/generated/mach-types.h'.  Stop.
make: *** [archprepare] Error 2
make: Leaving directory `/usr/src/kernels/3.12.26-1.20140808git4ab8abb.rpfr20.armv6hl.bcm2708'