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

[Alexander Sack]

Hello:

I have some weird behavior I'm trying to figure out and was wondering
if someone can point me in the right direction.  I'm running a FreeBSD
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.

For example:

[root at hagen ~]# file /bin/ls
/bin/ls: ELF 64-bit LSB executable, AMD x86-64, version 1 (FreeBSD),
dynamically linked (uses shared libs), stripped
[root at hagen ~]# ldd /bin/ls
/bin/ls:
	libutil.so.5 => /lib/libutil.so.5 (0x800630000)
	libncurses.so.6 => /lib/libncurses.so.6 (0x80073d000)
	libc.so.6 => /lib/libc.so.6 (0x800896000)
[root at hagen ~]# ls -l /libexec/
total 306
-r-xr-xr-x  1 root  wheel  163864 Aug 21  2007 ld-elf.so.1
-r-xr-xr-x  1 root  wheel  146420 Aug 21  2007 ld-elf32.so.1
[root at hagen ~]# export
LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/bin:/usr/lib:/usr/lib32:/usr/lib64
[root at hagen ~]# ls
/libexec/ld-elf.so.1: /usr/lib32/libutil.so.5: unsupported file layout
[root at hagen ~]# unset LD_LIBRARY_PATH
[root at hagen ~]# ls
(normal ls output)
[root at hagen ~]# ls -l /usr/lib/libut*
-r--r--r--  1 root  wheel  100518 Aug 21  2007 /usr/lib/libutil.a
lrwxrwxrwx  1 root  wheel      17 Sep 11 11:44 /usr/lib/libutil.so ->
/lib/libutil.so.5
-r--r--r--  1 root  wheel  103846 Aug 21  2007 /usr/lib/libutil_p.a
[root at hagen ~]# file /lib/libutil.so.5
/lib/libutil.so.5: ELF 64-bit LSB shared object, AMD x86-64, version 1
(FreeBSD), stripped

I would ASSUME that rtld would look at my LD_LIBRARY_PATH and use
/usr/lib to find libraries, not /usr/lib32.  Why does it insist on
picking /usr/lib32 when "/bin/ls" is CLEARLY a 64-bit binary?  This
doesn't make complete sense to me just yet.

Someone I'm sure is going "don't do that" and I agree.  The issue is
I'm porting a library/framework (boost) and it creates a runtime
LD_LIBRARY_PATH for its gcc toolchain with the above which breaks the
build ROYALLY on FreeBSD 64-bit machine.  I'm trying to come up with
the right heuristic here.

Any help would be much appreciated!

Thanks!

-aps