data structure:

First thing the kernel does is open its root filesystem - so we need a way to write a filesystem onto the hard disk, adjacent to the DOS filesystem, which is what this utility does.

This, the first article, is the first published mention of 386BSD. By this time, the project had been operational for 18 months, and William Jolitz was at Berkeley working on the Net/2 release.
In this installment, we discussed the beginning of our project and the initial framework that guided our efforts, in particular, the development of the 386BSD specification.

Reconciling segmentation to UNIX has never been easy, and with 386BSD its an even greater chore. The issues of supporting X86 segments in a Berkeley UNIX world.

A UNIX legacy, the "u." or per-process data structure, which held the kernel-related data of a process, was present on 386BSD prior to February 1991.

The "u." in more detail, handling kernel stack overflows in 386BSD.

Hardware context switch state description and the part where 386BSD context switching intrudes into the machine independent code semantics.

To find controllers and devices, we use tables to instruct device drivers where to probe and attach found peripherals and connect them with low-level drivers and high-level kernel subsystems.

How to bootstrap the system from hardware, loading the kernel program, itself a protected mode executable from secondary / nonvolatile / disk storage.

We initialized the processor with initial descriptor and page tables - one needs to run with the tables before activating memory/interrupt kernel functions.

The tool chest for 386BSD cross support included compiler, assembler, loader, libraries and include files. It did not include an emulation environment.

Where do you get the root filesystem, when you need it to make itself? Answer - you make it on another system, in this case one quite different, and then you break the recursion.

Nothing ever goes right the first time, so a incremental process of bringing up the filesystem, from standalone utilities to system initialization allows us to debug flaws in filesystem creation, often artifacts of its non-native creation.

What is it that makes up a filesystem? This depends very much on what kind of filesystem we are talking about.