I suppose that this is a serviceable set of man pages for standard OpenBSD kernel calls but you will have to type the name of the system call as part of the URL.

Several of the following links are to Watson’s (the thesis author) web site. They come up frequently on Google Unix of Linux searches.

An invitation to build a kernel, but I resist nor now.

Kernel sources with Capsicum comments.
The table of 532 kernel calls is generated. Consider the line with text “shm_open”; my Mac shell responds to man shm_open with an explanation, of sorts, of the meaning of this system call. This list should be a fairly authoritative list of kernel entries.

Here is a pregnant e-mail and answer that reveals one of the downsides of a monolithic kernel. A well designed large program can be documented so that partial understanding is possible and useful. I have no informed opinion whether Unix kernels are such.