Makefile.perf:1149: *** Missing bpftool input for generating vmlinux.h. Stop.

[Ingo Molnar]

So I've been getting this perf build failure for some time:

  kepler:~/tip/tools/perf> make clean
  Makefile.perf:1149: *** Missing bpftool input for generating vmlinux.h.  Stop.
  make: *** [Makefile:90: clean] Error 2

.. but if I clone a new repository, it works fine, until a point.

'make clean' doesn't work - and 'make mrproper' in the main kernel 
directory doesn't clean up properly.

Only if I do a brute-force:

	rm -rf tools/
	git checkout HEAD -f

does it get resolved.

The failure condition triggers if I Ctrl-C the following build a couple of 
times, without it being finished:


   cd tools/perf; make clean install
   ...

   LD      util/perf-in.o
   LD      perf-in.o
   CC      pmu-events/pmu-events.o
 ^Cmake[3]: *** [pmu-events/Build:43: pmu-events/pmu-events.o] Interrupt
 make[2]: *** [Makefile.perf:709: pmu-events/pmu-events-in.o] Interrupt
 make[1]: *** [Makefile.perf:264: sub-make] Interrupt
 make: *** [Makefile:113: install] Interrupt
 kepler:~/tip> perfi
 Makefile.perf:1149: *** Missing bpftool input for generating vmlinux.h.  Stop.
 make: *** [Makefile:90: clean] Error 2

Thanks,

	Ingo