This is a glibc 2.1 compatibility C software development kit for glibc 2.2. It is built under RedHat 7.0. To install, just untar i386-glibc-2.1-linux.tar.gz under /. The glibc 2.1 SDK will be installed under /usr/i386-glibc-2.1-linux. You can use /usr/i386-glibc-2.1-linux/bin/i386-glibc21-linux-gcc to compile/ link applications which are not compatible with glibc 2.2. Please note that glibc 2.2 is 100% run-time compatible with previous releases for glibc 2.x. This SDK is a compile/link time tool. It is not needed for the run-time compatibility for glibc 2.1. However, if there is a need to use glibc 2.1 at run-time, you can do # /usr/i386-glibc-2.1-linux/bin/i386-glibc21-linux-gcc -run-time ... to make the application use glibc 2.1 at run-time.