Date: Mon, 24 Mar 2014 14:41:56 +0100
From: chrubis@suse.cz
Message-ID: <20140324134156.GA5660@rei.suse.cz>
References: <1390298574-2966-1-git-send-email-wangxg.fnst@cn.fujitsu.com>
	<1390298574-2966-3-git-send-email-wangxg.fnst@cn.fujitsu.com>
	<20140203170843.GA4298@rei> <532BC78F.9050208@cn.fujitsu.com>
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Subject: Re: [LTP] [PATCH v2 3/3] fcntl/fcntl31.c: add I/O availability
 signals test for fcntl(2)
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Errors-To: ltp-list-bounces@lists.sourceforge.net
To: Xiaoguang Wang <wangxg.fnst@cn.fujitsu.com>
Cc: ltp-list@lists.sourceforge.net

Hi!
> > +}
> > +
> > +static void wait_io_ready(void)
> > +{
> > +	pid_t child;
> > +	int i;
> > +
> > +	fflush(stdout);
> > You should use tst_flush() or tst_fork() instead.
> >
> > Note: I've just added the tst_fork() and updated the test writing
> >       guidelines.
> >
> >> +	child = FORK_OR_VFORK();
> > The rest of the testcase would not run on uClinux so there is no reason
> > to use FORK_OR_VFORK() instead of fork().
> You said that the rest of the testcase would not run on uClinux, so
> we should use fork or tst_fork() directly.
> 
> Now I couldn't figure it out why the rest of the testcase would not run on uClinux,
> Makefile in syscalls does not filter out the fcntl directory. Could you give me some
> hint about this :-)

There is no fork() on uClinux, you have to emulate it using vfork()
which starts a new process but the memory of the two processes is still
shared (because there is no MMU) and if you do anything else than exec()
the result is undefined. To overcome this testcases ported to uClinux
self exec itself with special parameter that tells the test to run the
child function directly. Look at the lib/self_exec.c source.

-- 
Cyril Hrubis
chrubis@suse.cz

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