Add On System

The glibc build system supports add-on directories where you can drop them in and have them automatically get integrated into the build.

They get picked up if they provide a "sysdeps" directory or a top level "configure" script.

Configure Scripts

The configure scripts are run in the environment of the top level configure script. That means you have full access to variables the script has set. Here are the variables that you can rely on and their meanings.

Variable

Meaning

machine

value loaded from autoconf's host_cpu

os

value loaded from autoconf's host_os

vendor

value loaded from autoconf's host_vendor

submachine

cpu specified by --with-cpu for more specific cpu optimizations

dir

subpath to the source tree where the current configure script lives (e.g. when running "sysdeps/i386/configure", this will be "sysdeps/i386")

Other variables may be clobbered, but aren't really well documented. If you rely on one, please document it here.