和第2版相比，本版内容上*大的变化是，从以IA32和x86-64为基础转变为完全以x86-64为基础。主要更新如下： 基于x86-64，大量地重写代码，首次介绍对处理浮点数据的程序的机器级支持。 处理器体系结构修改为支持64位字和操作的设计。 引入更多的功能单元和更复杂的控制逻辑，使基于程序数据流表示的程序性能模型预测更加可靠。 扩充关于用GOT和PLT创建与位置无关代码的讨论，描述了更加强大的链接技术（比如库打桩）。 增加了对信号处理程序更细致的描述，包括异步信号安全的函数等。 采用新函数，更新了与协议无关和线程安全的网络编程。

The RISC-V Reader is a concise introduction and reference for embedded systems programmers, students, and the curious to a modern, popular, open architecture. RISC-V spans from the cheapest 32-bit embedded microcontroller to the fastest 64-bit cloud computer. The text shows how RISC-V followed the good ideas of past architectures while avoiding their mistake. Highlights include: - Introduces the RISC-V instruction set in only 100 pages, including 75 figures - 2-page RISC-V Reference Card that summarizes all instructions - 50-page Instruction Glossary that defines every instruction in detail - 75 spotlights of good architecture design using margin icons - 50 sidebars with interesting commentary and RISC-V history - 25 quotes to pass along wisdom of noted scientists and engineers Ten chapters introduce each component of the modular RISC-V instruction set--often contrasting code compiled from C to RISC-V versus the older ARM, Intel, and MIPS architectures--but readers can start programming after Chapter 2.