Wu Zhangjin studied Computer Science and Technology at Lanzhou University and obtained his Master's degree in Distributed and Embedded System in 2010. He is a Linux user and developer since 2004 and he co-founded the Open Source Community of Lanzhou University in 2006. He is an active open source contributor; he launched the Linux-Loongson/Community Project in 2009 and uploaded more than 100 patches to the Linux mainline. He reactivated the Tiny-Linux kernel project in 2011. He also developed some other open source projects, such as VnStatSVG and TP4CELL. He worked for a Chinese Loongson CPU application company and a world-leading embedded system company and now works on Linux system optimization for a leading Chinese Android smartphone company. Currently, his main focus includes real-time systems, Linux RAS, power saving, system fastboot, system-size optimization, and kernel debugging and tracing. His private website is http://tinylab.org; it is mainly about embedded system research and development. The extra content related to this book project will also be discussed there.