Embedded FreeBSD Cookbook phần 1 ppsx

Embedded FreeBSD Cookbook [...]... 214 214 C Kernel Loadable Modules 215 Overview Kernel Loadable Modules System Calls Device Drivers 215 215 219 2 21 The open Function The close Function The read Function The write Function 225 225 225 226 Commands 226 vii Preface Discussing embedded systems in general is difficult, because each embedded. .. are microwave ovens, MP3 players and cell phones 1 2 3 4 5 6 7 8 9 RESET 0 PREHEAT START STOP Press to Open Microwave Oven Figure 1- 1 Classic embedded system Load Balancer Server #1 Server #2 Server #3 TCP/IP Clustered Load Balancer As the Internet grew, the requirements of embedded systems also began to grow in complexity In addition to solving classic embedded systems problems, system designers were... is available free of charge It can be down­ loaded directly from the FreeBSD website at ftp://ftp .FreeBSD. org/pub /FreeBSD/ Or, if you're like me and want to have an actual CD, as well as support the FreeBSD effort, there are a number of retail outlets where FreeBSD can be purchased, such as the BSD Mall, http://www.bsdmall.com /freebsd1 .html, or a number of local retail outlets such as Staples, CompUSA... yet another way to support FreeBSD The FreeBSD distribution is an open source project If you’re interested, you can contribute time and source code development Information about contributing to FreeBSD development can be found on the FreeBSD website, http://www .freebsd. org/doc/en_US.ISO8859 -1/ articles/contributing/index.html In addition to its mature networking technology, the FreeBSD kernel con­ tains... management facilities and secure 6 Embedded FreeBSD Cookbook networking protocols The features and benefits of FreeBSD are summed up in the following paragraphs • Security FreeBSD offers security features that make it suitable for ecommerce applications, secure Internet transmission, and virtual private networks Many fixes to security-related bugs have been incorporated into FreeBSD over the years, to ensure... of the size command for the hostname program is in Listing 2 -1 # size hostname text data 39452 4020 bss 19 68 dec 45440 hex b180 stack heap unitialized data initialized data text Figure 2 -1 Process Running in Memory filename hostname Listing 2 -1 The output shows the text size as 39452 bytes, the data section as 4020 bytes and bss size of 19 68 bytes Stack and heap are assigned by the operat­ ing system... controller Chapter 10 , Building the Kernel, discusses the steps for building a custom kernel based on the hardware and specific features of the DIO Internet appliance Chapter 11 , System Startup, provides a discussion of the FreeBSD booting process and modifications necessary to the startup scripts to run the services required by the DIO appliance such as Tomcat, ssh and loading custom KLDs Chapter 12 , The CompactFlash... development Embedded Systems An embedded system consists of hardware and software designed to solve a specific application Many applications consist of more than simple computer hardware and software For example, an industrial vision system designed to control a robotic arm consists of an embedded computer, camera, display, and the robotic arm Each of these components are embedded systems on their own Embedded. .. evolved Classic embedded systems have been considered dedicated solutions to a single application In these classic systems, the hardware was custom designed to solve a specific application and the operating system was 2 Embedded FreeBSD Cookbook developed internally All the software was self-contained in nonvolatile RAM and there was a limited user interface Examples of these types of embedded systems... minimum of software, lending itself to some of the most limited embedded applications PicoBSD, a targeted version of FreeBSD, contains fully bootable systems that fit on a floppy disk In addition to the flexibility, many embedded systems boot from a DiskOnChip or CompactFlash device Many of these devices are readily supported by FreeBSD • License FreeBSD is distributed using the BSD License, which permits, . 10 9 The 11 1 System Call 11 1 The 11 2 System Call 11 2 The 11 2 System Call 11 2 The 11 3 System Call 11 3 The 11 3 System Call 11 3 The 11 4 System Call 11 4 The 11 5 System Call 11 5 The DIO. DIO Daemon 11 5 The 11 5 Structure 11 6 The 11 7 Function 11 7 The 11 9 Function 11 9 The 12 0 Function 12 0 Summary 12 2 7 Remote Management 12 3 Overview 12 3 Using Secure Shell (SSH) 12 3 The. The 10 System Call 10 The 11 System Call 11 The 12 System Call 12 The 12 System Call 12 An Example 12 Process IDs 13 Security 14 An Example 15 The 16 and 16 System Calls 16 File