Quoting Johnny Hughes <mailing-lists@xxxxxxxxxxxx>:
> Please see my earlier post:
>
> http://lists.centos.org/pipermail/centos/2005-June/007474.html
>
> We will continue to support i586 as much as possible, but i586 is not
> supported by RHEL-4.
>
> As I said, I have put in an upstream bug to try and have this corrected
> (it is a reproducible upstream error) ... and I am debugging the build
> issue as well.
Thanks. I've read it just after sending my previous mail (and than had
to go to
work).
The problem with glibc is somewhat deeper and more complex. This is my
understanding of things gathered from various sources over time (and parts may
be inacurate, so if anybody can correct me, it would be splendid).
At various points in time Red Hat made some somewhat conflicting
decisions. The
first was that Red Hat distributions must have NPTL. For NPTL support, there
are two components of system where it is implemented, kernel and glibc. Back
then glibc supported NPTL only for i686. NPTL support was later backported to
i586 and i486. Kernel should be fine with i486 and newer. There will
never be
i386 support for NPTL, since i386 lacks some assembly instructions needed to
implement it effectively (NPTL i386 system would be unusably slow).
Then, Red Hat dropped i386 kernels, and continued to support i586 and i686
kernels only. However on the glibc side, i386 and i686 builds were
used. This
broke things badly in Fedora Core 2 for i586 machines for some packages that
used Berkely DB library (most notably, Cyrus IMAPD was the most problematic
package).
Now, I'm not sure if this part is urban legend or reality. Apperently they
"fixed" it in Fedora Core 3. The fix was not i586 version of glibc (which
would be logical, glibc is one of the few rare packages that might actually
benefit from i586 instruction set, if nothing else than because of mandatory
NPTL support for Red Hat distributions). What they did was to build i386
version of glibc with NPTL part using i486 instructions (at that point
in time,
glibc folks have already backported NPTL to i486 and i586).
Now, *if* i586 is supported architecture for distribution (are they shipping
i586 kernel? what release notes for distro say?), then this should be
considered as a bug. Either i386 version of glibc must be patched the
same way
it was allegedly patched on Fedora Core 3 (to use i486 instructions for NPTL
support), or they finally need to give in and support i586 for glibc
(optionally dropping i386 glibc, as they did with kernel some time ago).
What might be checked first is if FC3 NPTL fix for i386 glibc is reallity? Is
it included with RHEL4 glibc?
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