Runtime Support - Novell LINUX ENTERPRISE SERVER 11 - ADMINISTRATION Administration Manual

6.1 Runtime Support

IMPORTANT: Conflicts between Application Versions
If an application is available both for 32-bit and 64-bit environments, parallel
installation of both versions is bound to lead to problems. In such cases, decide
on one of the two versions and install and use this.
An exception to this rule is PAM (pluggable authentication modules). SUSE
Linux Enterprise Server uses PAM in the authentication process as a layer that
mediates between user and application. On a 64-Bit operating system that also
runs 32-Bit applications it is necessary to always install both versions of a PAM
module.
To be executed correctly, every application requires a range of libraries. Unfortunately,
the names for the 32-bit and 64-bit versions of these libraries are identical. They must
be differentiated from each other in another way.
To retain compatibility with the 32-bit version, the libraries are stored at the same place
in the system as in the 32-bit environment. The 32-bit version of libc.so.6 is located
under /lib/libc.so.6 in both the 32-bit and 64-bit environments.
All 64-bit libraries and object files are located in directories called lib64. The 64-bit
object files you would normally expect to find under /lib and /usr/lib are now
found under /lib64 and /usr/lib64. This means that there is space for the 32-bit
libraries under /lib and /usr/lib, so the filename for both versions can remain
unchanged.
Subdirectories of 32-bit /lib directories which contain data content that does not de-
pend on the word size are not moved. This scheme conforms to LSB (Linux Standards
Base) and FHS (File System Hierarchy Standard).
►ipf: The 64-bit libraries for ia64 are located in the standard lib directories, there
is neither a lib64 directory nor a lib32 directory. ia64 executes 32-bit x86 code
under an emulation. A set of basic libraries is installed in /emul/ia32-linux/lib
and /emul/ia32-linux/usr/lib. ◄
56 Administration Guide