[Bug math/14343] Function logb() in math.h produces incorrect results for small inputs

["carlos_odonell at mentor dot com" <sourceware-bugzilla@sourceware.org>]

http://sourceware.org/bugzilla/show_bug.cgi?id=14343

Carlos O'Donell <carlos_odonell at mentor dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|WAITING                     |SUSPENDED

--- Comment #4 from Carlos O'Donell <carlos_odonell at mentor dot com> 2012-07-24 13:32:11 UTC ---
(In reply to comment #3)
> (In reply to comment #2)
> > Do you need a fix for this on the 2.15 stable branch?
> > 
> > Is it enough that 2.16 has the fix?
> > 
> > If you are compiling glibc yourself you can upgrade to 2.16.
> 
> For some computers I use, it's fine that 2.16 has the fix, but I also have to
> deal with some enterprise machines that will be using glibc 2.15 for quite a
> while (the bug was discovered while testing some internal math libraries on
> these machines). Since this problem is quite widespread -- anyone with 64-bit
> glibc 2.15 will have an issue -- and this affects basic math functionality,
> there really should be a fix on the 2.15 stable branch...

Andre,

Thanks for the response. If you would like to see progress made on this I would
suggest the following course of action:
* Checkout glibc 2.15
* Apply the change made for BZ #13954 e.g.
http://sourceware.org/git/?p=glibc.git;a=commit;h=89c9aa491a7cee97bf78a29cddbf0a25c902a671
* Build glibc and run the testsuite.
* Build your application against the newly built glibc using -Wl,-rpath and
-Wl,--dynamic-linker and see if it fixes your issue.

If the newly built glibc 2.15 fixes your issue then do the following:
* Add the keyword glibc_2.15 to this issue indicating that you are requesting a
backport to the 2.15 stable branch.
* Mention the exact commit that you backported and tested, and include your
testsuite results and the machine you tested on.

At that point the 2.15 stable release branch manager can *easily* pickup the
fix for inclusion in the next 2.15 stable release e.g. 2.15.1.

I'm marking this bug as suspended pending help from someone to work on
backporting and testing a fix.

If you have *any* questions about how to do any of the above steps we would be
more than welcome to walk you through it on libc-help@sourceware.org. Please
don't hesitate to ask, no question is wrong :-)

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