[CentOS] CentOS 4.4, libstdc++ 3.4.6 and NPTL

Aleksandar Milivojevic alex at milivojevic.org
Sun Sep 10 03:25:38 UTC 2006

Tim Jackson wrote:
> Can anyone offer any advice? Is this a bug in the libstdc++ package? Is
> there a likely workaround? I'm afraid I don't know enough about
> NPTL/libstdc++ to really understand the details of what's going on here.

I don't know much about NPTL/libstdc++.  However, what I do know is that 
Red Hat made decision to require NPTL very long time ago.  If your 
system can't run NPTL enabled kernel and glibc (or whatever other 
library), it is unsupported and it isn't likely anybody will work on it 
to fix it.  Even if you were paying Red Hat customer.  Things might 
work, and than they might mysteriously break one day.

I've mentioned one example in the other thread couple of days ago.  In 
FC2, glibc didn't have NPTL support on i586 (it used i386 version of 
glibc, and i386 doesn't have instructions needed to implement NPTL). 
The fix was to create "unclean" i386 package using i486 instructions to 
get NPTL support into i386 glibc.  However, note that the architecture 
(i586) was able to run NPTL-enabled glibc.  If your system can't run 
NPTL-enabled glibc at all (I don't know much about UML), than the 
problem most likely can't be fixed.  The fact that it used to work with 
the older versions is of little relevance here.  You were simply lucky, 
and your luck just ran out.

For example, if you don't have working NPTL it is very likely that some 
of the RHEL4/CentOS4 packages wouldn't work even with the older version 
of the libraries (cyrus-imapd is the one that would probably break, the 
way it was broken in i586 FC2, its DB4 based database backend heavily 
depends on NPTL).

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