On Sun, 2009-04-12 at 13:37 +0800, CAI Qian wrote:
> From: CAI Qian <[email protected]>
> Subject: Re: [LTP] fork05 test case fails due to optimization
> Date: Sat, 11 Apr 2009 04:02:41 -0700 (PDT)
>
> >
> >
> >
> > --- On Tue, 4/7/09, rohit verma <[email protected]> wrote:
> >
> >> From: rohit verma <[email protected]>
> >> Subject: [LTP] fork05 test case fails due to optimization
> >> To: [email protected]
> >> Date: Tuesday, April 7, 2009, 5:57 PM
> >> There is a change in compilation
> >> mechanism in LTP from Feb 09
> >> distribution.The previous Make mechanism did not provide
> >> any
> >> optimization while compiling the fork05 test program and
> >> the test used
> >> to Pass . However the newer Makefile uses optimization
> >> level 2 while
> >> compiling, if this file is executed the test case fails ..
> >>
> >
> > This is definitely a case. I can reproduce it on Fedora 10, so I have
> > created a bug of it, and copied the author Ulrich Drepper,
> >
> > https://bugzilla.redhat.com/show_bug.cgi?id=495296
> >
>
> Ulrich Drepper has pointed out in the above bug report that this failure
> was due to incorrect test code.
>
> The test code isn't correct. The compiler cannot look inside the asm
> statements in main() and see that they are really necessary. Based on
> the information given the compiler can drop some of them.
>
> Change all asms in main from
>
> asm(...)
>
> to
>
> asm volatile(...)
>
> and the code works fine.
>
> With the following patch, it works fine with and without compilation
> optimization.
>
> Signed-off-by: CAI Qian <[email protected]>
Thanks for the fix. But doesn´t apply for me :-)
patching file testcases/kernel/syscalls/fork/fork05.c
Hunk #1 FAILED at 178.
1 out of 1 hunk FAILED -- saving rejects to file
testcases/kernel/syscalls/fork/fork05.c.rej
Regards--
Subrata
>
> --- ltp/testcases/kernel/syscalls/fork/fork05.c.orig 2009-04-12
> 13:24:48.000000000 +0800
> +++ ltp/testcases/kernel/syscalls/fork/fork05.c 2009-04-12
> 13:26:28.000000000 +0800
> @@ -178,23 +178,23 @@
>
> modify_ldt (1, &ldt0, sizeof (ldt0));
>
> - asm ("movw %w0, %%fs" : : "q" (7));
> + asm volatile ("movw %w0, %%fs" : : "q" (7));
>
> - asm ("movl %%fs:0, %0" : "=r" (lo));
> + asm volatile ("movl %%fs:0, %0" : "=r" (lo));
> tst_resm(TINFO,"a = %d", lo);
>
> - asm ("pushl %%fs; popl %0" : "=q" (lo));
> + asm volatile ("pushl %%fs; popl %0" : "=q" (lo));
> tst_resm(TINFO,"%%fs = %#06hx", lo);
>
> - asm ("movl %0, %%fs:0" : : "r" (99));
> + asm volatile ("movl %0, %%fs:0" : : "r" (99));
>
> pid = fork ();
>
> if (pid == 0) {
> - asm ("pushl %%fs; popl %0" : "=q" (lo));
> + asm volatile ("pushl %%fs; popl %0" : "=q" (lo));
> tst_resm(TINFO,"%%fs = %#06hx", lo);
>
> - asm ("movl %%fs:0, %0" : "=r" (lo));
> + asm volatile ("movl %%fs:0, %0" : "=r" (lo));
> tst_resm(TINFO,"a = %d", lo);
>
> if (lo != 99)
>
>
> > CAI Qian
> >
> >> With Older Make mechanism
> >> cc -Wall -I../../include -g -Wall
> >> -I../../../../include -Wall
> >> fork05.c -L../../../../lib -lltp -o fork05
> >>
> >> With Newer Make mechanism
> >> gcc -g -O2 -I../../include -g -Wall -I../../../../include
> >> -Wall
> >> fork05.c -L../../../../lib -lltp -o fork05
> >>
> >> Note: If we compile the program in the same
> >> directory(/testcases/kernel/syscalls/fork) ,the
> >> optimization flag do
> >> not come into picture and the test case passes. The
> >> optimization is
> >> set by some top level Makefile
> >>
> >> Regards,
> >> Rohit
> >>
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