Note

Doc: https://www.freebsd.org/doc/en_US.ISO8859-1/books/developers-handbook/index.html

Also chekcout TrueOS: https://github.com/trueos/trueos

Layout

Directory	Description
bin/	Source for files in /bin
cddl/	Utilities covered by the Common Development and Distribution License
contrib/	Source for files from contributed software.
crypto/	Cryptographical sources
etc/	Source for files in /etc
gnu/	Utilities covered by the GNU Public License
include/	Source for files in /usr/include
kerberos5/	Source for Kerberos version 5
lib/	Source for files in /usr/lib
libexec/	Source for files in /usr/libexec
release/	Files required to produce a FreeBSD release
rescue/	Build system for the /rescue utilities
sbin/	Source for files in /sbin
secure/	Contributed cryptographic sources
share/	Source for files in /usr/share
sys/	Kernel source files
tests/	The FreeBSD test suite
tools/	Tools used for maintenance and testing of FreeBSD
usr.bin/	Source for files in /usr/bin
usr.sbin/	Source for files in /usr/sbin

This repo is really a monster, you can find everything here. For all commands you've came across, it's likely you will find the source code here!

Compiler

• usr.bin/clang

Kernel

FreeBSD is a monolithic kernel.

• sys/dev - Device Drivers
  • The number of drivers are not large, around 200-300. But I guess should be able to run on top of most platforms, coz I have never heard complaints about lack of device drivers.
  • sys/dev/mlx5
• sys/vm
• sys/sys

ifconfig

Apr 7: helped me find out how to get MTU size.