1 / 31

Chap. 2

Chap. 2. Embedded Linux Concept. Outline. 2.1 Linux Overview Unix/Linux History Linux Concept Linux Command 2.2 Embedded Linux Overview ARM Linux uClinux Embedded Linux Concept. Unix/Linux History. 1985: The “GNU manifesto” is published in the March

virgil
Télécharger la présentation

Chap. 2

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chap. 2 Embedded Linux Concept

  2. Outline 2.1 Linux Overview • Unix/Linux History • Linux Concept • Linux Command 2.2 Embedded Linux Overview • ARM Linux • uClinux • Embedded Linux Concept

  3. Unix/Linux History • 1985: The “GNU manifesto” is published in the March 1985 issue of Dr. Dobb's Journal. • 1989: SCO ships SCO UNIX System V/386, the first volume commercial product licensed by AT&T to use the UNIX System trademark • 1991 : Linus Torvalds develops Linux as an open source Unix clone • 1994 : Linux 1.0 is released. • 1995: SCO acquires UNIX Systems source technology business from Novell Corporation (which had acquired it from AT&T's UNIX System Laboratories). SCO also acquires UnixWare 2 operating system from Novell

  4. Unix/Linux History • 1996: Real-time Linux designated the RTLinux project released in 1996 by Michael Barabanov under Victor Yodaiken's supervision • 1997: Caldera ships OpenLinux Standard 1.1 May 5, 1997, the second offering in Caldera's OpenLinux product line • 2003: Linux Kernel Archive http://www.kernel.org/. The current full-featured version is 2.6 (released December 2003) and development continues • 2005: The latest stable version of the Linux kernel is 2.6.12.4 (released 2005-08)

  5. Outline 2.1 Linux Overview • Unix/Linux History • Linux Concept • Linux Command 2.2 Embedded Linux Overview • ARM Linux • uClinux • Embedded Linux Concept

  6. Linux Architecture • Linux Kernel • Provide basic OS mechanisms, file systems, device drivers...etc. • Libraries • C libraries, run-time libraries...etc. • Shell (Command line interface) • A user program that provides an environment for user interaction. • GUI • Graphic User Interface • System Services • Disk manager, Web server...etc. • System Utilities & User Applications • vim, ftp, ifconfig, firefox...etc. System Services System Utilities User Applications Shell (Bash, Csh…) GUI (Gnome, KDE…) Libraries (glibc) Linux Kernel Hardware (PC)

  7. Important Concept of Linux • You can simply regard a complete Linux system as two major parts: • Kernel • Root Filesystem • A roughly boot sequence of Linux: Now we can see the directory structure and files in hard disk Boot code Kernel Initiate hardware Mount Root FS Mounted as root (/) Execute /sbin/init Initiate Kernel functions Root Filesystem (Stored in hard disk) Execute /sbin/login

  8. Linux Root File System Ref. [1]

  9. Typical Directories • / : Root of the tree. • bin, sbin, usr/bin: software for the shell and most common Linux commands. • dev: device files, Linux regards devices as files, for example: HD0  /dev/hd0, printer1  /dev/lpt1. • home: contains individual user home directory (/export/home on sun computers). • tmp: holds temporary files. • var: contains files that vary in size. (Mail directories, printer spool files,logs, etc.) • etc: administrative files such as lists of user names and passwords. • usr: contains application programs

  10. The Linux Kernel • Task management • System calls • Memory management • Scheduler • IPC • File system • Device driver • Network stack

  11. Linux Kernel architecture • Architecture of a generic Linux system Ref. [3]

  12. Outline 2.1 Linux Overview • Unix/Linux History • Linux Concept • Linux Command 2.2 Embedded Linux Overview • ARM Linux • uClinux • Embedded Linux Concept

  13. Linux command -Basics man command: display online help, type q is exit • ls : display Information about files and directories -l display detail information -a display information for every file including hidden file in a directory • cd : move to directory • cd ~ : move to home directory • cd .. : move one directory up • cd dirname : change to directory dirname • cp : copy file (cp from-filename to-filename) • rm : delete file (rm filename ) • mv : move file (mv filename ./directory) • mkdir : create new directories • rmdir : delete empty directories

  14. Linux command - Basics • df : reports the amount of free disk space on any currently mounted filesystem • ln : creates a symbolic link to a files (ln -s originalfile linkfile) • more : display file contents in full screen and page by page (more filename) • shutdown : shutdown the system -h halt the system when the shutdown is complete -r reboot the system when the shutdown is complete • halt : shutdown the system now • reboot : restart computer • pwd : report current directory • who : show who is logged on • passwd : change password • login, logout : log in or log out system • startx : start X window

  15. Linux command - File Management • chown : change the ower user and group of file or directory (chown user:groupfile or directory) • chmod : change the permissions user and group of file or directory [ex] chmod ug+rx dirname, chmod 755 dirname • mount : attach the device to the filesystem [ex] mkdir /c (first make directory) mount /dev/hdc /c • umount : detach the device from the filesystem [ex] umount /c • uname : display system information <ex> uname -a • mkbootdisk : [ex] mkbootdisk --device /dev/fd0 2.4.20-8 build floppy boot disk ,kernel Ver. 2.4.20-8 • cat : concatenates files [ex] cat a.txt >> b.txt • fdisk : partition tool • mke2fs : format tool [ex] mke2fs /dev/fd0

  16. Linux command - Network • ping : send ICMP ECHO_REQUEST packets to network hosts[ex] ping 140.118.123.173 • telnet : connects the local host with a remote host[ex] telnet 140.118.123.173 • ifconfig : configure a network interface[ex] ifconfig eth0 140.118.123.173 • netstat : display network state • route : show/manipulate the IP routing table • ftp : file transfer tool [ex] ftp 140.118.123.173 • bin : switch to binary transfer mode • ascii : switch to ascii transfer mode • get filename : download file • put filename : upload file • bye : quit ftp • ls : list file and directory

  17. Linux command - Compress & Decompress For file • compress : • bzip2 : [ex] bzip2 filename  form filename.bz2 • zip : [ex] zip filename1 filename  form filename1.zip • gzip : [ex] gzip filename  form filename.gz • decompress : • bzip2 : [ex] bzip2 -d filename.bz2 • unzip : [ex] unzip filename1.zip • gzip : [ex] gzip -d filename.gz

  18. Linux command - Compress & Decompress For directory • tar : The GNU version of the tar archiving utility -z: gzip/ ungzip type -c: create a new archive -x: extract files from archive -v: verbosely list files processed -f: use archive file or device F (default "-", meaning stdin/stdout) • compress : [ex] tar -zcvf directory.tar.gz directory • usegzip to compress directory and generate directory.tar.gz. • decompress : [ex] tar -zxvf directory.tar.gz • use gzip to decompress and extract directory.tar.gz.

  19. Linux command - Search • find : find [pathnames] [conditions] • An extremely useful command for finding particular groups of files. • grep : grep [options] pattern [files] • Search one or more files for lines that match a regular expression pattern.

  20. Linux command - Process • ps : ps [options] -a : list all processes on a terminal -u : display processes for the specified users -x : display processes without an associated terminal

  21. Linux command - Process • Kill : kill [options] [PIDs] • Send a signal to terminate one or more processes.

  22. Outline 2.1 Linux Overview • Unix/Linux History • Linux Concept • Linux Command 2.2 Embedded Linux Overview • ARM Linux • uClinux • Embedded Linux Concept

  23. ARM Linux • ARM Linux [7] is a port of the successful Linux Kernel to ARM processor based machines. • ARM Linux is under almost constant development by various people and organizations around the world. • It reserves mostly generic Linux Kernel features, such as multi-tasking, memory management, and so on.

  24. ARM Linux • Important features for developers: • Multi-tasking • Support fork() system call • Memory Management Unit (MMU) • Support virtual memory • Support brk() system call • Executable File Format • Support standard ELF executable file format

  25. Outline 2.1 Linux overview • Unix/Linux History • Linux Concept • Linux Command 2.2 Embedded Linux Overview • ARM Linux • uClinux • Embedded Linux Concept

  26. uClinux • The name ‘uClinux’ [2] comes from ‘Micro(μ)-Controller Linux’. • The original uClinux was a derivative of Linux 2.0 kernel intended for micro-controllers without MMUs. • uClinux first ported to the Motorola MC68328: DragonBall Integrated Microprocessor.

  27. uClinux • Important features for developers: • Multi-tasking • fork() system call is not implemented • vfork() is used instead of fork() • No Memory Management Unit • Does not have autogrow stack and no brk() • Need to use mmap() to allocate memory • Need to set stack size of a program at compile time • No memory protection • Any program can crash another program or the kernel • Executable File Format • Only support FLAT executable file format

  28. Outline 2.1 Linux overview • Unix/Linux History • Linux Concept • Linux Command 2.2 Embedded Linux Overview • ARM Linux • uClinux • Embedded Linux Concept

  29. Embedded Linux Architecture • Basically, the embedded Linux architecture is the same as the generic Linux architecture. • The software such as glibc, bash, Gnome and KDE ... etc, are too large to be used in embedded system. • The common substitution for software in embedded system is listed below: • Glibc  uClibc • Bash  busybox, Sash • Gnome, KDE  Microwindow, Qt Embedded, MiniGUI • Login  Tinylogin • Standalone Utilities  busybox NOTE: Busybox is a program that integrates a lot of frequently used utilities into it.

  30. Embedded Linux Build Procedure • Make a Kernel image for your board • The make procedure of distribution of embedded Linux that you are using is different from the others but they are similar. • The common make procedure of Linux Kernel: • make xconfig (or menuconfig) • Configure your Kernel • make dep (not necessary in 2.6 Kernel) • Check dependency • make • Compile your Kernel and produce the Kernel image • Build a Root Filesystem • You can build it manually or automatically build via some tools or scripts. • Put all files you want in the Root Filesystem image. • Commonly used file systems: ext2 and romfs. • Copy Kernel and Root FS to Flash memory

  31. Reference [1] 鳥哥的linux私房菜 鳥哥著 上奇 [2] http://www.uclinux.org [3] http://www.xml.com/ldd/chapter/book/ bookindexpdf.html [4] http://linux.about.com [5] http://linux.vbird.org/ [6] http://www.cs.toronto.edu/~reid/csc209/02f/ [7] http://www.arm.linux.org.uk/

More Related