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Introduction to Embedded Systems

Introduction to Embedded Systems. Dr. Jerry Shiao, Silicon Valley University. Course Description. Concepts of Embedded Linux Development. Bootloader (i.e. Redboot, uBoot). Linux Library uclibc for microcontrollers(Kernel APIs or system calls). Linux File System and RamDisk.

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Introduction to Embedded Systems

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  1. Introduction to Embedded Systems Dr. Jerry Shiao, Silicon Valley University SILICON VALLEY UNIVERSITY CONFIDENTIAL

  2. Course Description • Concepts of Embedded Linux Development. • Bootloader (i.e. Redboot, uBoot). • Linux Library uclibc for microcontrollers(Kernel APIs or system calls). • Linux File System and RamDisk. • Crossplatform GNU toolchain to compile Linux and uclibc for target. • Concepts of Linux Kernel Development. • Develop loadable Kernel modules and load/unload the Kernel modules. • Develop Applications. • Hands-On Lab: • Cirrus Logic Microcontroller chip 9302 ARM 9 Core. 32 MByte RAM, 16 MByte Flash memory, network, USB, and serial ports. • Redhat Linux Host Development System to develop and download embedded Linux/RamDisk target systems. • Raspberry Pi SOC ARMV6 Core. 512 MByte RAM, 4 GigByte SD Card, HDMI, GPU, network and USB ports. • Raspbian Linux based on Debian distribution and optimized for Raspberry Pi. • References: • Building Embedded Linux Systems 2nd Edition, O’Reilly Media, 2008 • Materials included from Suleman Saya, UC Santa Cruz SILICON VALLEY UNIVERSITY CONFIDENTIAL

  3. Course Description • Class Evaluation. • 30 %: Midterm. First half material. • 30 %: Final. Second half material. • 30 %: Assignments. • 10 %: Attendance / Class Participation. • Reference: O’Reilly Book, Building Embedded Linux Systems, 2nd Edition • Assignment 1: • Build RAMDisk on Host Linux. • RedBoot BootLoader TFTP/Serial From Host Linux To Target Platform (Cirrus Microcontroller). • Assignment 2: • Compile Linux Toolchain For Cirrus Logic EP9302 ARM Platform. • Compile C Application With Linux Toolchain and Place In RAMDisk. • Assignment 3: • Compile Embedded Linux Kernel 2.6.29. • Compile uclibc For Embedded Linux System. • Assignment 4: • Compile BusyBox Application and Create RAMDisk. • Create Linux initialization file. • Assignment 5: • Use /proc File System. • Install Loadable Modules. • Assignment 6: • Export Kernel Symbols. • Install Kernel Thread. • Assignment 7: • GDB Debugger SILICON VALLEY UNIVERSITY CONFIDENTIAL

  4. Embedded Linux Course Outline • Section 1 Embedded Linux Introduction • Linux At the Beginning • GNU and GNU Public License (GPL) • Embedded Linux Criterias • Embedded Linux Development • Linux Kernel Infrastructure • Cross-Platform Development • Section 2 Embedded Linux Development • Embedded Linux Development Requirements For Host System • Setup Host System For Cross-Development • Setup Target Board For Cross-Development • Target Board Boot Process • Target Board / Host System Communication • RAM Disk SILICON VALLEY UNIVERSITY CONFIDENTIAL

  5. Embedded Linux Course Outline Section 3 Embedded Linux ToolChain ARM Tool-Chain Binutils Kernel Headers Cross Compiler First / Second Stage Glibc Library Section 4 Linux File System Linux File System Linux Source Directory Hierarchy Root File System File System Concepts Inodes Virtual File System /proc File System Spring 2014 SILICON VALLEY UNIVERSITY CONFIDENTIAL 5

  6. Embedded Linux Course Outline Section 5 Kernel Internals Kernel Modules Module Organization Module Installation (Insmod) and Removal (rmmod) Linux Device Drivers Character Drivers Block Drivers Major and Minor Number Section 6 Kernel Scheduling Process Fundamentals Process States Process Scheduling Preemptive Multitasking Cooperative Multitasing Scheduling Policy Process Classification Interactive Processes Batch Processes Spring 2014 SILICON VALLEY UNIVERSITY CONFIDENTIAL 6

  7. Embedded Linux Course Outline Section 7 Kernel Process / Treads Process VS Threads InterProcess Communications (IPC) Memory Constraints Thread Management User Level Threads Kernel Level Threads Clone() / Fork() / VFork() Threads Section 8 Linux Interrupt Handlers Linux Interrupt Handlers Fast Interrupt Handlers Slow Interrupt Handlers Top Half Handlers Bottom Half Handlers Tasklets Workqueues Spring 2014 SILICON VALLEY UNIVERSITY CONFIDENTIAL 7

  8. Embedded Linux Course Outline Section 9 GNU GDB GNU Tool Chain Debugger (GDB) gdbserver (Target) gdb (Host) GDB Build Procedure Section 10 Real Time Linux Real Time Linux Linux “Soft” Real Time “Hard” Real Time Linux 2.6 Real Time Preemptive Linux Kernel Real-Time Scheduler Hish Resolution POSIX timers Real Time Application Interface (RTAI) Interrupt Abstraction Spring 2014 SILICON VALLEY UNIVERSITY CONFIDENTIAL 8

  9. Section 1 Embedded Linux Introduction 1991 University Of Helsinki in Finland by Linus B. Torvalds. Originally Minux, alternative to DOS. Minux developed by Andrew Tanenbaum to teach Unix. Minux supported protected mode. Minux rewrote for additional funtionality and features as Linux. Currently all code in Minux has been replaced. Minux file system format supported under Linux. Core is the Virtual File System (VFS). Linux built with GNU compiler and library. Released on 10/1991. Linux is POSIX compliant. Compatiable with Unix System V. GNU utilities and tools (compiler, assembler, loader, etc) are freeware. GNU Public License (GPL) specifies any modifications to Linux has to be freely published. Linux is open source because of GNU utilities and tools. Spring 2014 SILICON VALLEY UNIVERSITY CONFIDENTIAL 9

  10. Section 1 Embedded Linux Introduction Embedded System Definition Computer system integrated into a larger applicances that is not a computer (i.e. oven, gas station pump, ATM machine) or small devices (i.e. cell phone, PDA Physcial size is small. The computer system is on a small board. CPU, RAM, and low power consumption. Based on concept of the microcontroller, single integrated circuit that contains all the technology required to run an application. Combined onto a chip. Reduces chips and wiring to control a device. Reduce complexity, size, and cost. CPU RAM for program and data storage. Flash memory for program storage. Input/Output interfaces (i.e. serial, USB, ethernet, USB). Timers. Embedded system designed to perform simple, repeatable tasks. Simpliying tasks reduces complexity, minimize CPU processing power, and minimize RAM/Flash requirements. Maximum performance for minimum size and weight. Not apparent to user. Provide device with network-ability, available as modem, ethernet port, USB, or wireless. Provide device with user Interaction, likely (i.e. cell phone, PDA, gas pumps, ATMs). Some run without human intervention, but might be required to respond to realtime events (i.e. LEDs). Spring 2014 SILICON VALLEY UNIVERSITY CONFIDENTIAL 10

  11. Section 1 Embedded Linux Introduction Users of Embedded System Manufacturing – Replaces general purpose computers to control equipment. Drive down manufacturing costs and subsequently drives down end user prices. Solution for complex problems in product design. Car has embedded systems to control brakes, ariconditioning, ignition systems. Without embedded systems, need complicated and fault prone electronics or general purpose PC. Consumer electronics – Cell phones, digital cameras, pagers, PDAs, DVD players, copiers, printers, scanners, fax machines, Network switches/routers, stereo systems, televisions, game consoles, electronic instruments, electronic toys. Consumer products – Ovens, dishwashers, washer, dryers, home security systems. Business products – automobile electronics (i.e. audio system, anti-lock brakes), ATMs, hospital life-support systems, hospital medical testing systems, airplane on-board electronic monitors. Spring 2014 SILICON VALLEY UNIVERSITY CONFIDENTIAL 11

  12. Section 1 Embedded Linux Introduction Linux as Embedded System Why use Linux? Other Embedded OS options (i.e. VxWorks by WindRiver, pSOS by WindRiver, QNX, Nucleus by Accelerated Technologies, RTKernel, Symbian OS, Microware OS-9 by RadiSys, Windows CE by Microsoft, OSE by Enea, MicroC by OS-II). Linux quality and reliability. Large community support (i.e. Google). No need to pay for customer support. Open source. GNU utilities and tools made Linux appealing. Even condensed version of Linux on dedicated system has many solutions. Linux Custom Distributions: Monta Vista, TimeSys, Linux Free Distirbutions: Redhat, Degian, and Suse. Multitasking scheduler allows many processes/threads to run at the same time. Symmetric Multi Processor (SMP) Memory protection between processes, prevents one process from bringing down system. Multiplatform solution since Linux runs on many CPUs (ARM, x386, PowerPC, MIPS). Networking protocols (TCP/IP, IP services, Netware, AppleTalk, Supports Virtual File System (VFS) for transparent access to many file systems. Dynamic loadable kernel modules. Spring 2014 SILICON VALLEY UNIVERSITY CONFIDENTIAL 12

  13. Section 1 Embedded Linux Introduction Linux Kernel Architecture Linux is modular, monolithic kernel. Kernel is single process with one address and memory space. Services (i.e. scheduler, file manager, memory manager) made through direct function calls. User space, each process (i.e. application) protected by their own user memory. Invalid memory access will crash only the process. Kernel space, memory space is not protected. Invalid memory access will crash the system. Linux High – Level Components User Space App1 App2 . . . Kernel Space Scheduler Device Drivers File Manager Networking uclibc Memory Manager . . . Architecture / Platform X386 PowerPC ARM MIPS . . . Spring 2014 SILICON VALLEY UNIVERSITY CONFIDENTIAL 13

  14. Section 1 Embedded Linux Introduction Linux Monolithic Kernel Linux is modular, monolithic kernel. Kernel is single process with one address and memory space. Services (i.e. scheduler, file manager, memory manager) made through direct function calls. Linux Kernel modules exported symbols and functions are directly callable by other modules. Linux Kernel makes invalid memory reference, the kernel and all user processes crashes. Contrast micro-Kernel. Services are separate processes. IPC between services to request service. QNX example of micro-Kernel. When QNX service makes invalid memory reference, the kernel does not crash, only that service crashes. struct_task data structure used by every process and thread. Allows Kernel to schedule both process and threads together. First process created is the init process and all other processes are child processes. Spring 2014 SILICON VALLEY UNIVERSITY CONFIDENTIAL 14

  15. Section 1 Embedded Linux Introduction Linux Directory Structure boot / etc lib sbin init usr var mnt proc dev grep mount bin student1 cdrom log tty0 /boot – Linux bootup files (i.e. Linux Kernel) /etc – Linux system configuration files. /etc/inittab – Processes started at bootup (i.e. Runlevel) /etc/fstab – File systems and mount points. /etc/passwd – Users are defined and user accounts. /bin – Linux system binaries. /sbin/init – Process runned during boot process. /usr/bin – Applications for the users. /lib – The shared libraries for dynamically linked modules. /var – Data changes when the Linux system is running. /var/log – The running Linux system updated log files. /dev – Devices that are available to Linux system. Devices are treated like files and devices can be read/written as files. /mnt – Storage devices (i.e. hard disk, CD-ROMs) must be attached to some directory before accessing. Directores are the mount points. /home – Each users have own directory and only place normal users are allowed to write. /proc – Special directory containing information about the kernel. /proc/devices – List of devices configured into current kernel. vmlinux inittab fstab passwd bin home devices Spring 2014 SILICON VALLEY UNIVERSITY CONFIDENTIAL 15

  16. Section 1 Embedded Linux Introduction Soft Real-Time Embedded System Time tolerance for an event to occur. ATM machine. Transaction occurs after 10 seconds or 20 seconds, but not critical to occur at the same time every time. At least the transaction completes. Video streaming. Best effort and minimized latency from event. Linux latency in scheduler and memory manager makes Linux Soft Real-Time. For Hard Real-Time, Linux Kernel must be rewritten. Hard Real-Time Embedded System Absolute deadline must be met and no deadline missed. Airline computers controls radar, alarm indicators, airplane controls. Nuclear reactor temperator gauges and sensors must trigger cool down action immediately or disaster will occur. Absolute deterministic response to an event. OS that provides required service in bounded response time. In bounded response time, need to know when event must occur. VxWorks provides the most real-time critical events. Real-time event is measured and response time is tested repeatedly. Spring 2014 SILICON VALLEY UNIVERSITY CONFIDENTIAL 16

  17. Section 1 Embedded Linux Introduction Real Time Linux 2.6 Preemption Linux 2.4 nonpreemptive. System call (uclibc library) completed before the CPU was released. Higher priority process or interrupt prevented from running. For example, keyboard not responsive until system call was completed. Linux 2.6 system call was preemptable. A process forced to release CPU. Real Time Scheduler Linux 2.6 scheduler determined time slice for each process and which process to run based on runqueue per priority level. Active and Expired priority arrays. Linux 2.4 scheduler uses one global runqueue. Traverse entire runqueue to determine next process to run. Scheduling Policies (NORMAL, FIFO, RR, BATCH) Process Class (Interactive, Batch, Real-Time) Interactive spends time performing I/O (i.e. editors). Batch do not need user interaction (i.e. compiler). Real-Time provide deterministic response time (i.e. robot controllers). Spring 2014 SILICON VALLEY UNIVERSITY CONFIDENTIAL 17

  18. Section 1 Embedded Linux Introduction Real Time Linux Development Requirements Cross Development Platform on Linux Host Development is done on a different platform than the target platform. Microcontrollers has limited resources, CPU is not powerful enough to run compiler, a file system, or a development environment. Host system running Linux 2.4, but the target system is Linux 2.6. The Linux 2.4 GCC compiler will be used to compile the Linux 2.6 GCC cross compiler. Host system is x86 processor, but the target system has ARM 9 based microcontroller. Cross compiler used to build toolchain (i.e. assembler, linker, utilties) for target system. Cross compiler and toolchain used to build Linux 2.6 Kernel for target system. Advantage of Linux based host. Target simulators on host allow testing before loading target system. Spring 2014 SILICON VALLEY UNIVERSITY CONFIDENTIAL 18

  19. Section 2 Embedded Linux Development Cirus Logic EP-9302 Microcontroller 200 MHz Cirrus Logic EP-9302 ARM920T core processor with math co-processor and MMU ARM stands for Advanced RISC Machine (Reduced Instruction Set Computer Instruction Set Architecture). Simplicity suitable for low power applications in mobile and embedded electronics. 90% of all embedded 32-bit RISC processors. 10/100 MBps Ethernet 2 USB Ports RS232 Serial Port Real-time clock and watch-dog timer A/D, D/A converter 32 MByte 100 MHz SDRAM, 6 MByte Flash Marverick Math Engine Spring 2014 SILICON VALLEY UNIVERSITY CONFIDENTIAL 19

  20. Section 2 Embedded Linux Development Cross Development Environment Host System will send bootloader commands over Target System serial port. Host system ethernet port send Linux Kernel image and RAMDisk to target system RAM. Ethernet Port Switch Serial Port Host System Target System 1) Bootload commands. 2) Target System console log. 1) Host Linux Distribution, RedHat Linux. 2)Target System Linux 2.6 3) GNU Cross Development. 4) Root permission. 5) tftp Server. 6) tftpboot directory. 7) IPNetwork 8) Minicom communicate to target over serial cable. 192.168.1.100 192.168.1.101 Transfer Kernel image and RAMDisk (ext2 File System) to Target System RAM or Flash. Spring 2014 SILICON VALLEY UNIVERSITY CONFIDENTIAL 20

  21. Section 2 Embedded Linux Development Linux Boot Process – Bootloader Reset Microcontroller First stage bootloader located in small ROM (2K or 4K Bytes). Initializes CPU, MMU, on-chip devices, configures memory map. ROM bootloader loads second stage bootloader (i.e. Redboot) from fixed address from flash to RAM. ROM bootloader must have flash driver. NAND Flash –large, less cost, cannot execute-in-place. NOR Flash – smaller, execute-in-place (i.e. Second Stage Bootloader execute from NOR). Second stage bootloader will load the Linux Kernel and RAMDisk from: Automatically decompress the Linux Kernel and RAMDisk from flash to RAM. Manually interrupt bootloader (<cntrl> <c>) and use tftp to load Linux Kernel from server. After Linux Kernel starts running, bootloader is no longer in RAM. Bootloader configuration (i.e. IP address, host system (server) IP address) saved in high address space in flash. Only for development and testing. Bootloader configured with the starting address space in flash where Linux is located and where RAMDisk is located. During development, bootloader will load Kernel and RAMDisk from host system. Bootloader executes a jump to the Kernel code to configure the microprocessor registers and start_kernel() function. Bootloader architecture specific. Bootloader has memory map for the flash and for loading Kernel and RAMDisk and will be different for another microcontroller. Spring 2014 SILICON VALLEY UNIVERSITY CONFIDENTIAL 21

  22. Section 2 Embedded Linux Development Linux Boot Process – Kernel Kernel initializes cache, hardware devices, and mounts root file system (i.e. RAMDisk). Without root file system, Kernel will hang. /etc directory contains Kernel configuration files (i.e. inittab, rc.d, fstab). Kernel executes the init process, reading its configuration file, /etc/inittab, and executes scripts dependent on selected runlevel. Init process executes startup script, /etc/rc.d/rc.sysinit, configuring and starting networking and other system services (i.e. /etc/rc.d/init.d contains service scripts). Init process enters a runlevel, where different processes are started by scripts to run activate the resources for that runlevel (default in /etc/inittab). Runlevel 5 used for graphical interface (used for PC). Starts services in /etc/rc.d/rc5.d. Runlevel 3 brings up the system console window (used for embedded system). Starts services in /etc/rc.d/rc3.d. Local initialization, /etc/rc.local. Spring 2014 SILICON VALLEY UNIVERSITY CONFIDENTIAL 22

  23. Section 2 Embedded Linux Development Linux Boot Process – /etc/inittab Format of inittab file entries: id:runlevels:action:process Id: unique sequence of 1-4 characters. runlevels: 0-6 runlevels for the specified action. action: -- initdefault: runlevel to enter (i.e. scripts in /etc/rc.d/rcx.d directory, where x=0 to 6) after system boot. -- sysinit: process executed during system boot before any boot or bootwait actions. -- boot: process executed during system boot. -- bootwait: process executed during system boot while init waits for its termination (i.e. /etc/rc). -- wait: process started when runlevel is entered and init will wait for termination. -- respawn: process will restart whenever it terminates. # inittab This file describes how the INIT # process should setup the system # in a certain run-level. Id:5:initdefault: #System initialization si::sysinit:/etc/rc.d/rc.sysinit l0:0:wait:/etc/rc.d/rc 0 l1:1:wait/etc/rc.d/rc 1 l2:2:wait/etc/rc.d/rc 2 l3:3:wait:/etc/rc.d/rc 3 l4:4:wait:/etc/rc.d/rc 4 l5:5:wait:/etc/rc.d/rc 5 l6:6:wait/etc/rc.d/rc 6 #Run gettys in standard runlevels 1:2345:respawn:/sbin/mingetty tty1 … #Run xdm in runlevel 5 X:5:respawn:/etc/X11/prefdm - nodaemon Spring 2014 SILICON VALLEY UNIVERSITY CONFIDENTIAL 23

  24. Section 2 Embedded Linux Development Linux Boot Process – Root File System Embedded system, RAMDisk is used for file system. No hard disk in embedded system. RAMDisk is in system memory and acts like a block device. Supports different kinds of file systems (i.e. FAT, ext2, ext3). Default file system is ext2. Before loaded from flash or tftp from host system, root file system is a compressed file. Decompressed into RAM as ext2 file system. Root file system must contain everything needed to support a full Linux system. The basic file system structure: Directories: /dev, /proc, /bin, /etc, /lib, /usr, /tmp Set of utilties (/bin): sh, ls, cp, mv, etc. System config files (/etc): rc.d, inittab, fstab, etc. Devices (/dev): hda, tty<x>, fd, etc. Runtime library used by utilities. Root file system is mounted in RAM from RAMDisk, persists in RAM until system reboots. Development option: NFS-mount the root file system from the host system. Using NFS need configuration options enabled when Kernel is built. Linux interface through Virtual File System (VFS), standard set of I/O interfaces that can be used over different devices (i.e. hard disk, CDROM, NFS, NTFS, Apple File System). Physical device abstacted away from the user. Common Open/Read/Write/Close APIs are used regardless of underlying file system. Spring 2014 SILICON VALLEY UNIVERSITY CONFIDENTIAL 24

  25. Section 2 Embedded Linux Development Linux Boot Process – Host System Requirements Host Linux distribution (i.e. Redhat Linux). GNU Cross Development environment. tftpboot directory (root level) contains the Kernel image and root file system (i.e. RAMDisk). NOTE: chmod –R 777 /tftpboot /etc/init.d directory contains start/stop scripts for services in the system. /etc/init.d/xinetd (extended InterNet Daemon) must be running. Manages all Internet-based connectivity (i.e. ftp, tftp, telnet, …). /etc/init.d/xinetd <start|stop|status|restart> /etc/xinetd.d directory contains the configuration files for all applications managed by xinetd (i.e. tftp configuration file is here). Included in the xinetd configuration file. Each xinetd application has separate file, organized per application for security reason and allow easier customization. IP addresses assigned to Host System and assigned to Embedded System must be on same subnet. /etc/services file contain the protocol/port number used by a service. Spring 2014 SILICON VALLEY UNIVERSITY CONFIDENTIAL 25

  26. Section 2 Embedded Linux Development Linux Boot Process – Host System Requirements For /etc/xinetd.d/tftp configuration file, tftp service must be enabled. /etc/xinetd.d/tftp service tftp { socket_type = dgram protocol = udp wait = yes user = root server = /usr/sbin/in.tftpd server_args = -s /opt/tftpboot disable = no per_source = 11 cps = 100 2 flags = IPv4 } Spring 2014 SILICON VALLEY UNIVERSITY CONFIDENTIAL 26

  27. Section 2 Embedded Linux Development Linux Boot Process – Host System Requirements Minicom application to communicate with target system. minicom –s (minicom setup mode). Set “BPS to 57600”, “No Flow Control”, “Data Bits 8, Parity None, Stop Bits 1. Set Hardware Flow Control to “No”. USB serial device allows user access, otherwise only root permission can initialize minicom. chmod 666 /dev/ttyUSB0 (command in /etc/rc.d/rc.sysinit). /etc/rc.local has local startup commands. Cirrus Logic Microcontroller with RS232 serial use Serial-to-USB converter. NOTE: Cirrus Logic Microcontroller USB not active until after Linux boots. Bootloader must have USB driver to use during boot. Spring 2014 SILICON VALLEY UNIVERSITY CONFIDENTIAL 27

  28. Section 2 Embedded Linux Development Linux Boot Process – Host System Requirements minicom -s [configuration] Filenames and path File transfer protocols Serial port setup Modem and dialing Screen and keyboard Save setup as dfl Save setup as … Exit Exit from Minicom A – Serial Device: /dev/ttyS1  /dev/ttyUSB0 B – Lockfile Location: /var/lock C – Callin Program: D – Callout Program: E – Bps/Par/Bits: 38400 8N1  57600 8N1 F – Hardware Flow Control: Yes  No G – Software Flow Control: No Change which setting? Spring 2014 SILICON VALLEY UNIVERSITY CONFIDENTIAL 28

  29. Section 2 Embedded Linux Development Linux In Desktop PC During powerup, BIOS in host (X86 system) access the hard drive Master Boot Record. In MBR is GRUB, Linux bootloader in Linux distributions. GRUB provides choice to boot one of multiple OS (i.e. Linux or Windows). /boot/grub/grub.conf contains GRUB configuration file with menu selection (i.e. which OS) and disk partition containing Linux Kernel and the root file system. GRUB loads Linux Kernel from /boot directory ( contains Linux Kernel(s), Kernel System Map(s), initrd (initial Ramdisk with drivers), Kernel config file(s) from Kernel build ). Initrd is temporary root file system with executables (i.e. insmod) and drivers to mount the root file system on disk. After mounting, initrd is unmounted and memory freed. NOTE: In embedded Linux systems, initrd is the final root file system. Linux Kernel starts init process. Init process is the root/parent process of all other process executing on Linux. Init process runs script, /etc/rc.d/rc.sysinit. Init process runs script, /etc/inittab, to execute scripts to start processes based on the runlevel. Spring 2014 SILICON VALLEY UNIVERSITY CONFIDENTIAL 29

  30. Section 2 Embedded Linux Development Target System Flash Boot – minicom console Power cycle target, when “+” sign on console appear, execute <ctrl> <c> to interrupt bootloader (Redboot) from continuing with autoboot. The bootloader prompt “Redboot> ” will appear. Redboot> fconfig –l Run script at boot: true Boot script: .. fis load ramdisk .. fis load zImage .. exec –r 0x800000 –x 0x300000 Boot script timeout (1000ms resolution): 1 Use BOOTP for network configuration: false Gateway IP address: 0.0.0.0 Local IP address: 192.168.1.200 Local IP address mask: 0.0.0.0 Default server IP address: 0.0.0.0 DNS servier IP address: 0.0.0.0 Set eth0 network hardware address [MAC]: true Eth0 network hardware address [MAC]: 0x00:0x00:0x00:0x00:0x4c:0x33 GDB connection port: 9000 Force console for special debug messages: false Network debug at boot time: false Spring 2014 SILICON VALLEY UNIVERSITY CONFIDENTIAL 30

  31. Section 2 Embedded Linux Development Target System TFTP Boot – minicom console Power cycle target, when “+” sign on console appear, execute <ctrl> <c> to interrupt bootloader (Redboot) from continuing with autoboot. The bootloader prompt “Redboot> ” will appear. Redboot> load –r –v –b 0x800000 –h 192.168.1.230 ramdisk.gz Loads data to the target RAM or flash file system. The IP address of Redboot (i.e. fconfig Local IP Address) must be in same subnet as tftp server IP address, 192.168.1.230. -r: Raw or binary data. Requires –b option to specify the location in RAM. -v: Display small spinner when the download is in progress. -b 0x800000: Address in RAM to load the data. This is the location of the RAMDisk as configured internally in Redboot. -h 192.168.1.230: IP address of the tftp server. ramdisk.gz: The name of the file on the tftp server. Redboot> fis load zImage Flash Image System. Loads the file, zImage, from the FIS directory. Once loaded, image can be executed. Redboot> exec –r 0x800000 –s 0x300000 Execute the Linux kernel from Redboot internal configuration. -r 0x800000: Address in RAM of the RAMDisk (i.e. Root File System). -s 0x300000: Length of the RAMDisk image. Spring 2014 SILICON VALLEY UNIVERSITY CONFIDENTIAL 31

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