Overview of the Book
To make life easier, Chapter 1, Introduction, presents a general picture of what is inside a Unix kernel and how Linux competes against other well-known Unix systems.
The heart of any Unix kernel is memory management. Chapter 2, Memory Addressing,explains how 80×86 processors include special circuits to address data in memory and how Linux exploits them.Processes are a fundamental abstraction offered by Linux and are introduced in Chapter 3, Processes. Here we also explain how each process runs either in an unprivileged User Mode or in a privileged Kernel Mode. Transitions between User Mode and Kernel Mode happen only through well-established hardware mechanisms called interrupts and exceptions. These are introduced in Chapter 4, Interrupts and Exceptions.In many occasions, the kernel has to deal with bursts of interrupt signals coming from different devices and processors. Synchronization mechanisms are needed so that all these requests can be serviced in an interleaved way by the kernel: they are discussed in Chapter 5, Kernel Synchronization, for both uniprocessor and multiprocessor systems.One type of interrupt is crucial for allowing Linux to take care of elapsed time; further details can be found in Chapter 6, Timing Measurements.
本书简介
简单一点，不啰嗦！
第一章《导言》，总体介绍了Unix内核内部实现机制和Linux与其他知名的类Unix系统如何PK；内存管理是所有类Unix系统的核心。第二章《内存寻址》，阐释了带有特殊电路的80X86处理器是如何在内存中对数据寻址操作以及Linux如何使用这些数据。进程是Linux提供的基本抽象单元，在第三章会介绍进程有关的内容；在这一章我们将解释每个进程是如何运行在无特权的用户模式以及有特权的内核模式的。用户模式和内核模式之间的转换只能通过成熟稳定的硬件机制来实现，这些机制就是中断和异常。第四章《中断和异常》就是介绍这些内容的。在很多场景中，内核必须处理来自不同设备或处理器的大量中断信号，这是就需要同步机制来实现所有的请求都能被内核以交错的方式进行处理，从而的得到相应的服务：我们将会在第五章讨论这部分内容——《内核同步，为单处理器和多处理器而生》。有一种类型的中断对于Linux处理的时间有着严格的限制，更多详情请见第六章——《定时诊断》。
Chapter 7, Process Scheduling, explains how Linux executes, in turn, every active process in the system so that all of them can progress toward their completions.Next we focus again on memory. Chapter 8, Memory Management, describes the sophisticated techniques required to handle the most precious resource in the system (besides the processors, of course): available memory. This resource must be granted both to the Linux kernel and to the user applications. Chapter 9, Process Address Space, shows how the kernel copes with the requests for memory issued by greedy application programs.
Chapter 10, System Calls, explains how a process running in User Mode makes requests to the kernel, while Chapter 11, Signals, describes how a process may send
synchronization signals to other processes. Now we are ready to move on to another essential topic, how Linux implements the filesystem. A series of chapters cover this
topic. Chapter 12, The Virtual Filesystem, introduces a general layer that supports many different filesystems. Some Linux files are special because they provide trapdoors to reach hardware devices; Chapter 13, I/O Architecture and Device Drivers,and Chapter 14, Block Device Drivers, offer insights on these special files and on the corresponding hardware device drivers.
第七章—《进程调度》，这一章节解释了Linux是如何轮流地执行系统中的每一个活动进程，以便使得所有进程都能够达成它们的目标。接下来我们再度聚焦内存，进入到第八章《内存管理》。这一章阐述了Linux系统处理这些最宝贵的资源所需的复杂的技术：可用内存（当然，处理器除外）。这一资源必须分配给Linux内核和应用程序。第九章《进程地址空间》向我们展示了内核是如何应付内存中来自应用程序发送来的请求的——这些请求来自那些“贪婪的”应用程序。【“贪婪”一词描述应用请求的频繁和调度任务的复杂——译者按】
第十章《系统调用》，本章阐释了处于用户态的进程是如何在运行过程中向内核发出请求；第十一章《信号》则描述了一个进程是如何向其他进程发送同步信号的。至此我们谈论了Linux内核中关键的几大功能，现在我们已经做好了向下一个关键问题冲刺的准备了，即Linux是如何实现文件系统的。我们将花连续几章来阐述这个问题。第十二章《虚拟文件系统》介绍了一个支持许多不同文件系统的通用接口层；有些Linux文件很特殊因为它们提供了访问硬件设备的“活动天窗”。第十三章《I/O框架和设备驱动》，第十四章《块设备驱动》则提供了有关这些特殊文件和相应硬件设备驱动的详细信息。