getpid() kernel service

[marc at arnor.uucp]

getpid is a unix system call.  as such it is defined in
/lib/syscalls.exp, rather than in kernex.exp.  All of the
entries in syscalls.exp are also available to kernel extensions.

(Take some care in this.  Those syscalls which read/write user
data, such as read, will fail if passed a supervisor buffer.
So you must think about the semantics of a system call you 
issue from a kernel extension.  This is not a problem for getpid).