Non-Shared Libraries  and  Dynamic Shared Objects
     -------------------------------------------------

In IRIX 3 and IRIX 4, Silicon Graphics used static shared libraries 
in order to maintain binary compatibility across hardware platforms
and operating system releases.  

With IRIX 5,  Silicon Graphics has moved to using Dynamic Shared Objects
in order to continue to guarantee binary compatibility across platforms
and operating system releases AND to meet the requirements of the SVR4 ABI.
In particular, using DSOs is required for compliance with the SVR4 ABI.

Silicon Graphics believes that DSO is far superior to non_shared
compilation mode in application portability, binary compatibility, 
memory usage, and system performance.  Indeed, almost all executables
in IRIX 5.2 are constructed using Dynamic Shared Objects.

DSOs allow SGI to ship platform-specific implementations of 
performance-critical functionality (eq. libm.so, libgl.so).  Programs
intended to run on multiple platforms will likely benefit from this.  In
addition, application programs will benefit from performance and reliability
improvements in DSOs without the applications having to be rebuilt and
re-released.

For some applications, there is a small performance penalty associated
with DSOs; and we are continuously working to improve the performance of
these programs.  In addition, the SPEC benchmark suite requires the shipment
of non_shared versions of a few libraries.   Currently, these are the only
non_shared libraries shipped by Silicon Graphics.  

Silicon Graphics will continue to respond to the changing needs of
its customers.   While SGI currently ships only those non_shared libraries
required by SPEC, a compelling customer need for a library that does not
currently exist in /usr/lib/nonshared will be considered; please contact SGI.

But please be aware that internal interfaces sometimes change due to 
continuous improvement in the OS and/or compilers.  This change is 
transparent to DSO users; but applications built with non_shared libraries
might require relinking in future releases.

See Also:
	dso(5)