System Libraries
Early in the dark ages of the SPARC port of Linux, we first used an
a.out libc4 as the system C library. Several
factors were behind this. First, we used a.out
SunOS binaries to bootstrap the first-ever Linux/SPARC systems, so we
knew that a.out worked. Second, this was the most stable libc source
base at the time. I hope that not very many (if any) SPARC
systems running this C library exist any longer. All native Linux
binaries using libc4 were statically linked.
ELF-based libc5 was the next library for Linux/SPARC. The earliest
complete distributions used this for the system libraries. Shared
ELF libraries were fully supported on SPARC.
Today, most Linux/SPARC systems are glibc/ELF based and will probably
remain this way for the foreseeable future.