libc.7: Add a few historical details on Linux libc4 and libc5

Just for historical interest. Details taken from
http://www.linux-m68k.org/faq/glibcinfo.html.

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>

diff --git a/man7/libc.7 b/man7/libc.7
index bc11d1c27cd2dbc67e4f4e8e10a0b39a1f38a4b2..8d0237951718aa892dc6841a0f3d8af24b37b8a9 100644 (file)
--- a/man7/libc.7
+++ b/man7/libc.7
@@ -64,8 +64,13 @@ In the early to mid 1990s, there was for a while
 a fork of glibc 1.x created by Linux developers who felt that glibc
 development at the time was not sufficing for the needs of Linux.
 Often, this library was referred to (ambiguously) as just "libc".
-Linux libc released major versions 2, 3, 4, and 5
-(as well as many minor versions of those releases).
+Linux libc released major versions 2, 3, 4, and 5,
+as well as many minor versions of those releases.
+Linux libc4 was the last version to use the a.out binary format,
+and the first version to provide (primitive) shared library support.
+Linux libc 5 was the first version to support the ELF binary format;
+this version used the shared library soname
+.IR libc.so.5 .
 For a while,
 Linux libc was the standard C library in many Linux distributions.