Re: perf_events: zero time running and enabled, but non-zero count

From: Frederic Weisbecker
Date: Mon Nov 02 2009 - 16:20:47 EST

On Sun, Oct 25, 2009 at 07:37:09PM -0700, Corey Ashford wrote:
> I'm getting this error on a Power5 box:
> ../../lib/find_next_bit.c: In function âext2_swabpâ:
> ../../lib/find_next_bit.c:168: warning: passing argument 1 of
> â__swab64pâ from incompatible pointer type
> make: *** [util/find_next_bit.o] Error 1
> I looked at the code and it looks ok to me. There's a cast from an
> "unsigned long *" to a "unsigned long long *", but those types should be
> of the same size (in -m64 mode), so I don't know why this is failing.

Yeah, it's ok because we have the BITS_PER_LONG check. But gcc is not
aware of that and just consider the cast as breaking the strict aliasing

Can you tell me if the following patch works for you? (only for
this build error).


diff --git a/tools/perf/Makefile b/tools/perf/Makefile
index 800783d..167bc04 100644
--- a/tools/perf/Makefile
+++ b/tools/perf/Makefile
@@ -846,8 +846,9 @@ util/bitmap.o: ../../lib/bitmap.c PERF-CFLAGS
util/hweight.o: ../../lib/hweight.c PERF-CFLAGS
$(QUIET_CC)$(CC) -o util/hweight.o -c $(ALL_CFLAGS) -DETC_PERFCONFIG='"$(ETC_PERFCONFIG_SQ)"' $<

+KFNB_FLAGS = `echo $(ALL_CFLAGS) | sed s/-Wstrict-aliasing=3//`
util/find_next_bit.o: ../../lib/find_next_bit.c PERF-CFLAGS
- $(QUIET_CC)$(CC) -o util/find_next_bit.o -c $(ALL_CFLAGS) -DETC_PERFCONFIG='"$(ETC_PERFCONFIG_SQ)"' $<
+ $(QUIET_CC)$(CC) -o util/find_next_bit.o -c $(KFNB_FLAGS) -DETC_PERFCONFIG='"$(ETC_PERFCONFIG_SQ)"' $<

perf-%$X: %.o $(PERFLIBS)
$(QUIET_LINK)$(CC) $(ALL_CFLAGS) -o $@ $(ALL_LDFLAGS) $(filter %.o,$^) $(LIBS)

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