The majority of UNIX system administrators in the world do not have access to UNIX source code. Many software support specialists also do not have source to refer to. However, most UNIX systems do come with /usr/include header files that are usually straight from the UNIX source tree.
In this chapter, we will talk about the header files, what they contain, and how we can use them when trying to track down why our system panic’ed. In the next chapter, we will take a look at the kernel symbol table or namelist and see how it relates to the /usr/include header files.
Both the /usr/include files and the kernel symbol table are big pieces in the overall puzzle that we are trying to piece together.