Some Links to the RTEMS Source Tree

The RTEMS source tree is a little bit complex, as you might expect since it holds an entire OS for multiple APIs, CPUs and BSPs etc.

The tree is essentially split into two important subtrees

cpukit: holds all the CPU independent pieces. Here are descriptions of the key directories with more links.
c/src/lib: CPU (libcpu) and BSP (libbsp) support

There is more stuff under c/src:

c/src/libchip: Drivers for various chips.
c/src/librtems++: A C++ API to RTEMS. Quite Useful. IMO, this should reside under cpukit...
c/src/libnetworking: This is not RTEMS networking but various contributed networking applications. Some of them are quick ports from UNIX and have caused name-clashing problems in the past. RTEMS networking is under cpukit/libnetworking