• Implement processes, thread, scheduler, synchronisation, VM, Virtual file system , Unix OS
• Use QEMU emulator to run and GDB for debugging
• Kernel module which
• Develop filesystem in linux kernel to detect files containing bad patterns
• System call handle malicious cases and prevents memory leaks and unnessary memory allocation
• FIle encrytion, decryption in Linux using CryptoAPI
• Kernel locking, Producer-Consumer, Netlink sockets and throttling
• Developed a kernel module which when loaded instantiates a producer-consumer work queue and a kernel thread to process the queue. The queue contains various job requests such as Contenation of multiple files etc.
• Decipher process scheduling and understand effective capacity utilization under general and real-time dispositions
• Understand concurrent execution on SMP platforms through kernel synchronization and locking techniques
• Clock subsystem
• Process communication techniques through signals and IPC mechanisms
• Kernal Audio driver

• Cryptographic Hash Function for random data & String manipulation
• Transform data / data process/ reporting
  • Cut and awk script : open network port
  • sort & uniq
  • parsing log file
• Network scripting & automation of distributed system
  • config a mini network and script for remote system
• test env : Vagrant & Virtual box Centos7 vagrant up

• FreeBSD
• kernel extension
• The XNU kernel (doc : /docs/xnu-kernel.md)

• Extensible firmware interface

• hardware

• Kernel space : XNU kernel: BSD, Mach, IO

• Quartz, OpenGL, Core Animation, Core Image, Audio , Text, Quicktime

• XNU kernel

• Kernel extension

• kernel address space management

• Memory Allocation in Mach `kern_return_t kmem_alloc(vm_map_t map, vm_offset_t *addrp, vm_size_t size);

kern_return_t kmem_alloc_contig(vm_map_t map, vm_offset_t *addrp, vm_size_t size, vm_offset_t mask, int flags);

void kmem_free(vm_map_t map, vm_offset_t addr, vm_size_t size);`

• BSD layer
• Network kernel extension
• Virtual file syste
• Unified Buffer Cache
• The Libkern Library

• Cocoa framework
• C++
• XCode
  • Compiler for c/c++, objective c
  • sourcecode debug
  • API + header files - used for kernel dev
  • profiling tools - measure code execution time + app dev + performance bottleneck
• kernel extension
• kernel extension template
• logfile /var/log/kernel.log

- kernel framework
- IOkit framework 

• THE I/O KIT MODEL

  • hardware
  • usb device

• THE INFO.PLIST FILE

  • list of drivers
  • probe score

• THE KERNEL LIBRARY: LIBKERN

  • os object
  • tracking mem leaks
  • container class
  • query a container for object

• USB specification and architecture
• USB subsystem provided by I/O Kit

• BSD layer
• socketAPI
• protocol handler
• network interface
• network kernel extension NKE
• Network memory buffer
• IO Kit : write driver for network hardware

• IOKit Audio Support

• SamplePCIAudioDevice

• IOAudioDevice

• IOAudioStream

• MyAudioEngine

• Driver & hardware init

• audio driver's IOAudioDevice subclass

• config hardware device provider

  • PCI & Thunderbolt, IO region
  • USB devices

• register audio control IOKit/audio/AudioDefines.h.

• create input mute control IOAudioToggleControl::createMuteControl

• implement Audio Engine

  • I/O in an audio driver
  • Allocate sample buffers and associated IOAudioStream instances.
  • performAudioEngineStart()
  • Header File for the MyAudioEngine Class

• I/O Engine Initialization

• Creating and Initializing Audio Streams

• Starting and Stopping the Audio Engine

• Engine Operation: Handling Interrupts and Timestamps

• Physical connection
• command protocol
• Transport layer driver
• Building a RAM disk device
• Partition scheme
• Media filter driver
  • Develop a filter scheme for encryption

• process
• signal
• fs
• pipe
• C
• IO

• C/C++
• Go arsenal CGO
• OpenSSL

• https://en.wikipedia.org/wiki/Kernel_(operating_system)
• https://docs.01.org/clearlinux/latest/guides/kernel/kernel-development.html

• Darwin kernel (mirror): https://github.com/apple/darwin-xnu
• Apple opensource : https://developer.apple.com/opensource/