From mboxrd@z Thu Jan 1 00:00:00 1970 From: pebolle@tiscali.nl (Paul Bolle) Date: Mon, 11 May 2015 11:58:11 -0000 Subject: Problem building kernel 4.0 with gcc5 Werror In-Reply-To: References: Message-ID: <1431345487.2398.81.camel@x220> To: kernelnewbies@lists.kernelnewbies.org List-Id: kernelnewbies.lists.kernelnewbies.org On Sat, 2015-05-09 at 18:28 -0500, Victor Rodriguez wrote: > I am trying to build the kernel 4.0 with gcc 5 . But I found the > following problem : > > builtin-report.c comparison of constant ?-1? with boolean expression > is always false > > THe problem is that gcc5 has new warnings: > > A new command-line option -Wbool-compare has been added for the C and > C++ compilers, which warns about boolean expressions compared with an > integer value different from true/false. > https://gcc.gnu.org/gcc-5/changes.html I think the problem is actually that the code is broken. See commit fefd2d9619de ("perf report: Fix branch stack mode cannot be set") in linux-next which links to http://lkml.kernel.org/r/1423967617-28879-1-git-send-email-hekuang at huawei.com . > I was checking the Makefile of tools/perf/ anda aprently they became > every warning into an error. Werror (tools/perf/Makefile.perf has this line # Define WERROR=0 to disable treating any warnings as errors. Perhaps that might help you get past this build error. I don't know, I never tried it. But the best thing here seems to use that patch. I guess it should eventually show up in the v4.0.y-stable tree.) > Now I wonder if someone is working on this changes so I can take their pathces. > > Do you know any easy way that GCC use to avoid this kind of problems > > All the help is more than welcome Hope this helps, Paul Bolle