Why does adding /usr/lib32 to LD_LIBRARY_PATH break 64-bit binaries?

[Alexander Sack]

On Fri, Oct 24, 2008 at 8:50 AM, Peter Jeremy
<peterjeremy at optushome.com.au> wrote:
> On 2008-Oct-24 10:43:04 +0200, Wojciech Puchar <wojtek at wojtek.tensor.gdynia.pl> wrote:
>>> 6.1-RELEASE-amd64 machine.  If I add /usr/lib32 to my LD_LIBRARY_PATH
>>> it breaks all of my binaries on my 64-bit machine.
>>
>>what do you expect else?
>
> Well, the rtld should be smart enough to recognize 32-bit .so's and
> skip them when binding a 64-bit executable.  Whilst having /usr/lib32
> in LD_LIBRARY_PATH doesn't make sense from a solely FreeBSD perspective,
> I have done similar things when writing cross-platform scripts (to
> avoid having to use platform-dependent code).
>
>>this will make system trying to bind 32-bit libs to 64-bit program. it
>>can't work
>
> rtld shouldn't attempt to bind 32-bit libs to 64-bit programs.

Bingo!  I don't care what the LD_LIBRARY_PATH is, a 64-bit binary
should NEVER attempt to load a 32-bit library (at least by default).
If anything, rtld should just exit with can't find library exception.
What its doing now in my book is just wrong in everyway.  The name of
the shared object is no longer enough to verify a match, it also needs
to check the arch bits as well.

I agree with everyone on this list that for FreeBSD, the gcc toolset
initialization should always contain /lib (and in fact I am going
further and saying that al *NIX platforms should probably always check
/lib since its the default and its there during bootup (that was a
good point btw)).  I think the issue has been cross platform builds
and the way Linux has it organized.  I have submitted a patch to add
/lib back to the Boost folks but I still want to understand this
behavior on FreeBSD - what am I missing?

Final note, I thought that /usr/lib would have the major number
versions linked just like /usr/lib32 so the above would just work.
Right now the issue is libutil.so.5 isn't found not because /lib isn't
in the LD_LIBRARY_PATH, i.e  If I make a symlink in /usr/lib just like
the /usr/lib32 file structure, it all just works.  I was just saying
above that I was wondering why major numbers aren't actually available
as links in /usr/lib like they are in /usr/lib32.

-aps