Hello FreeBSD

Build the documentation

You don’t need to depend on GitHub.

For a quick and dirty build, install Asciidoctor however you like and build: pkg install asciidoc xdg-utils

make doc

install gnome

Google it!

Move to bash shell

pkg install bash
chsh -s /usr/local/bin/bash root
#logout
echo $SHELL

[link]

compile the kernel

# download the kernel
sudo svn co --trust-server-cert --non-interactive https://svn0.us-east.freebsd.org/base/stable/11/ /usr/src
# first take backup
cp -Rp /boot/kernel/ /boot/kernel.backup
# determine ur arch
uname -a
# in my case amd64
cd /usr/src/sys/amd64/conf/
# copy kenel .config
cp GENERIC NEWKERNEL
# compile!
cd /usr/src
make buildkernel KERNCONF=NEWKERNEL
# install!
make installkernel KERNCONF=NEWKERNEL

Hello world userland example

make c
.userland/hello

Kernel command!

Google: freebsd kernel module hello world

kldstat
make
make load
make unload
make clean

hello LKM

How to use it:

$cd hello
$make
$kldload ./hello.ko
$kldunload ./hello.ko

syscall LKM

How to add your own custom syscall to FreeBSD then use it from userland

$cd syscall
$make
$kldload module/syscall.ko
$./test/call
$dmesg
$kldunload module/syscall.ko

cdev LKM

Simple char dev, Reference: /usr/share/examples/kld/cdev

echo LKM

Another simple char dev, because "cdev LKM" not working now, and this works smoothly. [Reference]

Side note #1

/usr/src/sys/ the best reference and learning tool for a newbie FreeBSD kernel hacker

Side note #2: Debugging

The FreeBSD Developer’s Handbook, specifically Chapter 10
[Debugging Kernel Problems by Greg Leh]

mkdir hook

$cd mkdir_hook/
$make
$mkdir anything

keylogger

$cd keystroke_hook
$make
$kldload ./read_hook.ko
$dmesg

Kernel Queue Data Structures

All lists related macros here: #include <sys/queue.h>, see queue(3)

Synchronization Issues

<sys/lock.h>, <sys/mutex.h>, see mutex(9)

<sys/sx.h>, see sx(9)

proc Structure

<sys/proc.h>

ps -aux Module

Linux kernel modules act almost like $(ps aux) command.

CodeStyle

FreeBSD codestyle: `style(9) and style.Makefile(5)

The FreeBSD regression testing tools

src/tools/regression `src/tools/

Google: Micro Benchmark Checklist for FreeBSD

Chapter 8. Configuring your FreeBSD custom Kernel - FreeBSD handbook

1. This chapter contains all the steps in detail. Please don’t abbreviate it.
2. Don’t make that in gnome, use ttys, Please -- my laptop always sleep with gnome (I don’t mean 'that', sorry) --
3. Ch 9. Building and Installing a FreeBSD Kernel - developers-handbook is complementary.

Chapter 10. Kernel Debugging - developers-handbook

Places

All Kernel modules exist in /boot/kernel
$dmesg content at boot-time === /var/run/dmesg.boot
Another tool for finding hardware is pciconf(8), which provides more verbose output. pciconf -lv
FreeBSD source code /usr/src/sys, If this place not exist, Google: get freebsd source code /usr/src/sys, that’s easy. sounds like git clone, but using svn.. I don’t try to make this page a refernce .. so google it…
/var/log/messages records the kernel messages from every successful boot. While, dmesg(8) will print the kernel messages from the current boot.
/boot/kernel/kernel.old location of old kernel - last successful & bootable kernel :)
/etc configuration files

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