System.map is a file on Linux and Unix-like operating systems that lists symbol addresses for the kernel. This file is useful for debugging and malware analysis related to rootkits.
Each line of this file concists of an Address, Type, and Name:
...
c0ffeec0 T sys_open
...
Types are single character: T (text/code), D (initialized data), B uninitialized data (BSS), R (read-only data), …