mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-09-07 03:18:31 +00:00
![]() When compiling perf tool code with gcc 4.4.7 I'm getting following error: CC util/session.o cc1: warnings being treated as errors util/session.c: In function ‘perf_session_deliver_event’: tools/perf/util/include/linux/bitops.h:109: error: dereferencing pointer ‘p’ does break strict-aliasing rules tools/perf/util/include/linux/bitops.h:101: error: dereferencing pointer ‘p’ does break strict-aliasing rules util/session.c:697: note: initialized from here tools/perf/util/include/linux/bitops.h:101: note: initialized from here make[1]: *** [util/session.o] Error 1 make: *** [util/session.o] Error 2 The aliased types here are u64 and unsigned long pointers, which is safe for the find_first_bit processing. This error shows up for me only for gcc 4.4 on 32bit x86, even for -Wstrict-aliasing=3, while newer gcc are quiet and scream here for -Wstrict-aliasing={2,1}. Looks like newer gcc changed the rules for strict alias warnings. The gcc documentation offers workaround for valid aliasing by using __may_alias__ attribute: http://gcc.gnu.org/onlinedocs/gcc-4.4.0/gcc/Type-Attributes.html Using this workaround for the find_first_bit function. Signed-off-by: Jiri Olsa <jolsa@redhat.com> Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com> Cc: David Ahern <dsahern@gmail.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1393434867-20271-1-git-send-email-jolsa@redhat.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> |
||
---|---|---|
.. | ||
cgroup | ||
firewire | ||
hv | ||
include | ||
lguest | ||
lib | ||
net | ||
nfsd | ||
perf | ||
power | ||
scripts | ||
testing | ||
thermal/tmon | ||
usb | ||
virtio | ||
vm | ||
Makefile |