Chapter 3. Kernel Services
3.1 Kernel Organization
The FreeBSD kernel can be viewed as a service provider to user processes. Processes usually access these services through system calls. Some services, such as process scheduling and memory management, are implemented as processes that execute in kernel mode or as routines that execute periodically within the kernel. In this chapter, we describe how kernel services are provided to user processes, and we explain some of the ancillary processing done by the kernel. Then we describe the basic kernel services provided by FreeBSD and provide details of their implementation.
All FreeBSD user-level processes originate from a single process that is crafted by the kernel at startup. ...