[Xenomai-help] Re: What happens if task entry function returns?

[Jan Kiszka <jan.kiszka@domain.hid>]

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M. Koehrer wrote:
> Hi Jan, 
> 
> I found out, that is issue seems to be related to the NPTL (native posix thread library).
> The pthread library in use was 
> /lib/tls/i686/cmov/libpthread.so.0
> which is part of the Debian (testing) package libc6-i686.
> (see http://packages.debian.org/testing/libs/libc6-i686)
> 
> When renaming the lib/tls to lib/tls.disabled the pthread library in use is
> /lib/libpthread.so.0
> and then it is working perfectly!

...which does not yet explain WHY the other scenario fails.

> 
> It seems that the i686 optimized libc is not fully compatible with Xenomai.

That's not true in such a common form. We are using NTPL libs for i586
and i686 (SuSE builds) without /general/ issues. Still, specific
problems like this may sleep somewhere.

> I read about this library at Romain Lenglet's web page:
> http://www.csg.is.titech.ac.jp/~lenglet/howtos/realtimelinuxhowto/index.html
> I think this library uses the NPTL (Native Posix Thread Lib).
> The i686 optimized library shows the value
> NPTL 2.3.6  
> at 
> getconf GNU_LIBPTHREAD_VERSION
> The "old" pthread lib shows the value:
> linuxthreads-0.10
> 
> Now, I tried to reconfigure Xenomai with --enable-x86-sep to use
> the NPTL but this did not help either.

That only influences the way syscalls are passed down into the kernel.

> When I rename now  /lib/tls to /lib/tls.disabled, the application complains
> about the missing NPTL support in the library.
> Well, I have now a solution that works:
> I can use the standard pthread lib and not the i686 optimized NPTL.
> However, as NPTL seems to be a performance benefit, I think it could be
> worth to get this combination up and running.
> 
> Is there anybody out there that uses a Debian based system with the i686
> optimized libc that works perfectly?
> 
> BTW: I am using xenomai 2.2.4 from end of October.
> 

Again my question: is the issue SMP related?

Reproducing your problem over a qemu box (with or without SMP) failed so
far for me. But I'm not on your glibc.

Jan


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