Date: Tue, 12 May 2015 22:05:28 +0200
From: Cyril Hrubis <chrubis@suse.cz>
To: Darren Hart <dvhart@linux.intel.com>
Cc: Shuah Khan <shuahkh@osg.samsung.com>, linux-api@vger.kernel.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        John Stultz <john.stultz@linaro.org>, Ingo Molnar <mingo@elte.hu>,
        Peter Zijlstra <peterz@infradead.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Davidlohr Bueso <dave@stgolabs.net>,
        KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Subject: Re: [PATCH 1/5] selftests: Add futex functional tests
Message-ID: <20150512200528.GA1336@rei>
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Hi!
> >> I'm happy to do that, but I would like to make sure I'm doing the right
> >> thing.
> >
> >The right thing here is to add -pthread to CFLAGS which sets both flags
> >for preprocessor and linker (see man gcc).
> 
> Hi Cyril,
> 
> Thanks. I read that, and mentioned it, but my concern with -pthread in the
> CFLAGS and LDFLAGS is that it is a non-standard compiler flag. I
> understand we have a number of gcc-isms in our build - but do we want to
> add more?
>
> I'm also struggling to find any kind of prescribed documentation on this
> beyond the short blurb in the gcc man page which describes what this
> option does, but not when to use it. I'll need something concrete to
> justify changes to testcase Makefiles to Shuah.

Sorry to mislead you with the pointing at gcc man page.

It is a Linux standard. Have a look at pthreads manual page:
http://man7.org/linux/man-pages/man7/pthreads.7.html

"On Linux, programs that use the Pthreads API should be compiled using
 cc -pthread."

Or any pthread_foo() manual page that starts with:

"Compile and link with -pthread."

The portable way i.e. POSIX would be getting compiler flags with getconf
but as this is a Linux kernel testsuite I would not bother with that.
Hmm, and it looks like this is not implemented on Linux anyway.

-- 
Cyril Hrubis
chrubis@suse.cz
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