Table of Contents

Linux Kernel Programming
- General
- Style & Documentation
- RT Linux
- Drivers
  - Network
  - Code/Examples
- Debug
  - Hints
- Locking
  - Hints
- Memory
- Random

Linux Kernel Programming

General

Style & Documentation

RT Linux

Real-Time Linux Wiki
Linux Foundation Wiki: BROKEN-LINK:Real-Time LINUXLINK-BROKEN
Linux Foundation Wiki: BROKEN-LINK:HOWTO setup Linux with PREEMPT_RT properlyLINK-BROKEN
Linux Foundation Wiki: BROKEN-LINK:HOWTO build a simple RT applicationLINK-BROKEN

Drivers

J. Corbet, A. Rubini, G. Kroah-Hartman: Linux Device Drivers (LDD3)
P. J. Salzman, M. Burian, O. Pomerantz: The Linux Kernel Module Programming Guide
Tariq Shureih (Intel): HOWTO: Linux Device Driver Dos and Don'ts
Linux Kernel Documentation: Driver Model
Linux Kernel Documentation: Building External Modules

Network

PHY Abstraction Layer
phylink (SFP)

Code/Examples

ioctl called from within kernel code

Debug

Embedded Linux Wiki: Debugging by printing
Stack Overflow: Linux-kernel debug printouts?
Linux Kernel Documentation: pr_debug()

Hints

Use WARN_ON() and BUG_ON() macros for run-time assertions.
Force a backtrace (programmatically) using dump_stack().
Use this code in a Makefile to enable pr_debug(), dev_dbg() and friends based output in kernel ring buffer:
- for a particular source file
```
CFLAGS_<basename>.o := -DDEBUG
```
- or; in whole kernel module
```
ccflags-y += -DDEBUG
```
  See this Wiki page how to show such messages.

Locking

Linux Kernel Documentation: Proper Locking Under a Preemptible Kernel
Linux Kernel Documentation: Spin locks
Linux Kernel Documentation: Generic Mutex Subsystem
Linux Kernel Documentation: RT-mutex implementation design

Hints

Suppress scheduling by use of function preempt_disable().
Functions irqs_disabled() and in_interrupt() are very helpful regarding protection of non-preemptive code (see also the comments at Stack Overflow).
For use of [num]delay(), usleep() and friends see timers-howto.txt.

Memory

Mel Gorman: Understanding the Linux Virtual Memory Manager
Ulrich Drepper: What every programmer should know about memory
Server Fault: How is kernel oom score calculated?

Random

Jake Edge: A system call for random numbers: getrandom()
ArchWiki: Rng-tools