Transcript 4.1 Starting Parameters (Stage 2)

Chapter 4
Embedded Software Architectures
Professor Ruei-Xi Chen
E-mail: [email protected]
Http://www.csie.sju.edu.tw
SJU/CSIE
Outline
4.1 Bootloader
4.2 Embedded Operating System
4.3 Root Filesystem
4.4 Graphic User Interface of Embedded system
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Software Component Images of Embedded Systems
 Three Software Component Images
 Bootloder image
 Kernel image
 Root Filesystem image
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Typical Embedded SW Image Maps
 Pre-fixed instructions
 Can be Fetched from fixed
locations during power up.
Ex: Start from 0x00000000
 Pre-allocated Solid Devices:
 FLASH
 ROM
 Or EEPROM
 Typical image map is as shown.
Bootloader
Boot Parameters
Kernel
Root Filesystem
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4.1 Bootloader
4.1 Bootloader
4.2 Embedded Operating System
4.3 Root Filesystem
4.4 Graphic User Interface of Embedded system
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4.1 What is a Bootloader?
 A special small program
 that also called a bootstrap loader.
 The only job of a boot loader:
 To load other software for the operating system to start.
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4.1 The Linux Bootloader
 To initialize platform:
 Load the Linux kernel
Kernel can be downloaded by using tftp/bootp.
Kernel is accessed from flash if it resides in Flash.
 Run the Linux kernel
 Setup various initialization parameters:
Command line: root=/dev/nfs ….
Platform ID (stored in r1)
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4.1 Available Bootloaders for ARM Platforms
 U-Boot: Universal Bootloader
 A firmware for many CPU architectures and boards with
full source code under GPL.
 http://sourceforge.net/projects/u-boot
 RedBoot
 A comprehensive debug and bootstrap firmware solution
for the development, deployment, and management of
embedded devices.
 http://www.ecoscentric.com/ecos/redboot.shtml
…
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4.1 Boot Processes
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4.1 Categories of Bootloader Processing
Single-Stage boot loaders
2. Multi-Stage boot loaders
 Capable of offering good functionality and portability
 Often used
1.
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4.1 Coding Style of Multi-Stage Bootloaders
 A Two-Stage Boot Loader is employed.
 Coding Styles in Stage 1
 Mostly coding with assembly languages
For the efficiency purpose
 Coding Styles in Stage 2
 Coding in C languages
Well readability and portability
For ease of complex function realization
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4.1 Mission of Two-stage Bootloaders
 Stage 1：
 Hardware Initializing & Load Preparing
During Power up or System Reset
 Assembly language
 Stage 2：
 Load Kernel Image
 Launch Kernel Boot
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4.1 Hardware Initialization (Stage 1)
 Detect the machine type
 Initialization
 Mask(阻擋) all Interrupt request
 Set Processor’s clock rate
 Memory & Register Initialization
 Initialize required peripherals
 Initialize the Interrupt controller and Install Interrupt
handler.
 Initialize the indicators (LED etc.)
 Disable Data and Instruction Cache Memory.
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4.1 Load Preparing (Stage 1)
 Prepare RAM space for Stage 2
 Setup stack
 The stack space had better be times of the memory page (4
KB)
 Set stack pointer: sp = stage2_end - 4
 Jump to the Entry-point of Stage 2
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4.1 Memory Map
0x0000,0000
0x0000,0400(1KB)
Stage1, 1K
(Image of boorloader)
Stage2, 64K
0x0001,0000(64KB) (Image of boorloader)
(Blank)
Flash
Kernel Image
(Blank)
ramdisk
stage2_start
Stack_Pointer: stage2_end - 4 Stage1 allocated RAM
sapce for Stage 2
stage2_end
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RAM
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4.1 Initialization (Stage 2)
 Initial
 Initialize the Stage 2 required hardware
At least initialize one serial port
Initialize Timers
 Examine memory map
Assure the mapping address is accessible
 Clear memory
 Loader Enabled
 Loader: a section code of Boot image
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4.1 Load Kernel Images (Stage 2)
 Memory allocation
 Allocate Kernel image space
MEM_START + 0x8000
32k for boot parameters, kernel page table
 Allocate Root filesystem space
MEM_START + 0x00100000
 Loading
 Load and extract Kernel image from flash to RAM.
 Load and extract the root filesystem image from flash to
RAM.
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4.1 Launch Kernel Boot (Stage 2)
 Set the starting parameters of kernel.
 Tagged list methods
 Start kernel
 Initialize System
 By calling kernel functions
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4.1 Starting Parameters (Stage 2)
 Set the starting parameters of kernel
 Use the tagged list to pass the starting parameters
Starting with ATAG_CORE tag
Ending with ATAG_NONE tag
(After version 2.4.x)
 The starting parameters that need to be set by the Bootloader:
ATAG_CORE
ATAG_MEM
ATAG_CMDLINE,
ATAG_RAMDISK
ATAG_INITRD
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4.1 Start Kernel (Stage 2)
 Jump to MEM_START + 0x8000
 Setting the CPU registers
 R0=0
 R1=machine type ID
Linux/arch/arm/tools/mach-types
 R2=Base address of the starting parameter list in RAMs
 CPU mode
 The interrupt needs to be inhibited (IRQs and FIQs).
 It needs to set the CPU as SVC (Switch Virtual Circuit) mode.
 Cache and MMU setting
 Disable MMU
Neglect if the embedded system has no MMU (memory
management unit).
 Disable data cache
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4.1 Initializing System
 Calling kernel functions
 Various objects and services functions of kernel:
Task objects
Timer services
Memory management services
…
 Loading system device drivers
 Initialize hardware devices
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4.1 XSBase255B Bootloader Operations
 Object
 To finish the preparing work properly before the kernel
starting.
 Stage1 :
 Devices initialization with the Assembly language
 Stage2 :
 Complex initialization implemented by the C language, but
never call any function of glibc.
 How to jump to the main()?
Directly jump to the entry point of the main
External wrappers: write a trampoline program (assembly),
and let it be the entry point of the stage 2. Jump to the
main from here. The reverse direction is used as it returns.
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4.1 Some Second-Stage Boot Loaders
 Used for Stage 2
 bootman
 GRUB
 LILO
 MasterBooter
 NTLDR
 XOSL
 BootX
 loadlin
 Gujin
 OSL2000 Boot Manager
 Boot Camp
 Syslinux
 GAG (Graphical Boot Manager)
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4.1 The Bootloaders Support
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4.1 Sites of the Embedded X86 Bootloaders
 alios




 http://www.telos.de/linux/alios/default.htm
LinuxBIOS
 http://www.acl.lanl.gov/linuxbios/index.html
NILO(netboot,etherboot)
 http://nilo.sourceforge.net
TinyBIOS
 http://www.pcengines.ch/tinybios.htm
ROLO
 ftp://www/elinos/pub/elinos/rolo
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4.1 Other Embedded Bootloader Sites
 LILO/GRUB
 http://lilo.go.dyndns.org
 http://www.gnu.org/software/grub/
 Blob :LART project
 http://www.lart.tudelft.nl/lartwareblob/
 U-Boot
 http://u-boot.sourceforge.net/
 http://www.denx.de/re/DPLG.html
 http://sourceeforge.net/projects/u-boot
 http://armboot.sourceforge.net/
 RedBoot
 http://www.ecoscentric.com/snapshots/
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4.1 The Typical Bootloaders
 NTLDR (NT Loader )
 For 2000/XP/Server 2003
 Does not appear in Windows Vista
 To load an NT-based OS
 LILO (LInux LOader)
 A generic boot loader for Linux
 GRUB (GNU GRUB)
 A boot loader package from the GNU Project
 U-Boot (universal bootloader)
 Portable
 Easy to port and debug
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4.1 The Typical Bootloader Supporting
x86
NTLDR
★
LILO
★
GRUB
★
Blob
ARM
MIPS
PPC
NIOS
(Altera)
Microblaze
(Xilinx)
★
★
★
U-Boot*
★
★
★
★
RedBoot*
★
★
★
★
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4.1 Operation Modes of Boot Loaders
Boot loading Mode
 Autonomous Mode
 Loading during power on
2. Downloading Mode
1.
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4.1 The Downloading mode
 An alternative of the Boot loading mode
 The bootloader often use the following protocols are to connect
the Target and Host:
 UART Protocol
Usually as xmodem, ymodem, zmodem
The speed is limited
 TFTP Protocol (network transferring)
The Host needs to provide TFTP service
 Downloading documents from the Host
 Such as the image
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4.2 Embedded Operating System
4.1 Bootloader
4.2 Embedded Operating System
4.3 Root Filesystem
4.4 Graphic User Interface of Embedded system
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4.2 Architecture of Embedded Systems
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4.2 Typical Embedded Operating Systems
Windows CE /Mobile Windows
Palm OS
EPOC
uC/OS-II
Symbian OS
RTOS:
 VxWorks, pSOS…
 Linux:
 uClinux, Montavista Linux, ARM-Linux…






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4.2 WinCE Architectures
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4.2 Advantages of WinCE
 Benefits
 Built-in NAND Flash bootloader, SD Host
 Various embedded IP
 Design time reduction with a supporting reference
board & RTOS
 Various design applications
 Key Applications
 Wireless PDA
 Smartphone
 Game machines
 Point-of-Sale terminals
 Portable media players
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4.2 Linux Kernel
From http://www.xml.com/ldd/chapter/book/bookindexpdf.html
(GPL)
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4.2 Open Source Embedded Linux
 Embedded Debian Project
 Convert Debian to an embedded OS
 ETLinux
 For PC104 SBC’s
 uCLinux
 For microprocessors that don’t have MM
 uLinux (muLinux)
 Distro fits on a single floppy
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4.2 Kernel Space
 Kernel structure
 Data structure of Process
Process ID, Priority, Status, Registers used,
Interrupt, Global variables
 Process Management
User’s service routines in a forever loop
 Time Management
Required time delay for interrupt
 Inter-process Communication & Synchronization
Semaphores, message boxes, message queues
 Memory Management
Mechanism of memory allocation and release
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4.2 Kernel Architecture of RTOS
 Kernel Primitive
 Issue system calls for Interrupts
 Interfacing the processes to the system
 Interrupt Service Routine (ISR)
 Software interrupt & hardware interrupt
 Process Scheduler
 A dispatcher
First-come-first-serviced Scheduling (FCFS)
Priority Scheduling (PS)
Preemptive
Non-preemptive
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4.2 Basic Kernel Program
 Synchronization




 Semaphores: Accessed by Pend() and Post()
Buffer management
 Request() and Release()
Data transfer
 Send() and Receive()
Interrupt Management
 EnableINT() and DisableINT()
Process Management
 Process Control Block (PCB)
 Process state: running, waiting, ready
 Context switch
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4.2 uCLinux Structure
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4.2 Building XSBase255B Linux kernel
 Setup Kernel
 Directories and files
 Setup Makefile and config.in
 Add applications to Kernel
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4.2 Kernel Directory Structure
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4.2 Kernel Configuration
 Three part of files required
1. Makefile
2. Config.in
3. Configuration tools(圖形介面, 用戶配置…)
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4.2 Make Kernel
 $make menuconfig
 $make dep
 $make zImage
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4.3 Root Filesystem
4.1 Bootloader
4.2 Embedded Operating System
4.3 Root Filesystem
4.4 Graphic User Interface of Embedded system
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4.3 Root Filesystem Types
Filesystem
Write
Always
Power
Down
reliability
Compress
In
RAM
CRAMFS
n
n
n
y
n
JFFS2
y
y
y
y
n
JFFS
y
y
y
n
n
NFTL/Ext2
y
y
n
n
n
NFTL/Ext3
y
y
y
n
n
RAMDISK/
Ext2
y
n
n
n
y
NFTL:NAND Flash Transfer Layer
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4.3 The cramfs Filesystem
 Cramfs
 The compressed ROM filesystem (or cramfs)
 A free (GPL'ed) read-only Linux file system designed for
simplicity and space-efficiency
 Cramfs is used on a number of embedded systems and small
devices
 File size <16MB
 Capacity<256MB
 Kernel’s PAGE_CACHE_SIZE=4096B
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4.3 The ext2 Filesystem
 Advantages:
 Support up to 4TB memory
 Support 1012 bytes long file name
 symbolic link : index table speed up
 Disadvantages :
 IDE device design: 1block=512, 1024, 2048…
 NAND FLASH not support
 ERASE/Write
 No balance management
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4.3 The JFFS2 Filesystem
 JFFS2
 A log-structured file system designed for use on flash devices
in embedded systems.
 Features
 Compression ratio < cramfs
 Better than ext2 in (r/w/erase)
 Power down no crash
 If full slow down performance
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4.4 Graphic User Interface of Embedded system
4.1 Bootloader
4.2 Embedded Operating System
4.3 Root Filesystem
4.4 Graphic User Interface of Embedded system
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4.4 Future Multi-mode IA Terminal
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4.4 Common Features: Graphic User Interface
PDA：PPT 8846
3D Graphics
Typical GUI
HP iPAQ rz1710 Navigator
203 MHz S3C2410
7,0 x 1,3 x 11,4 cm
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4.4 Embedded System GUI More
www.cybervision.com.tw/
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第四章：嵌入式軟體架構
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Tiny-X GUI Fundamentals
GUI Builder for Linux: the Glade
Glade and GTK+
 What is GTK?
 GTK+: GIMP Tool Kit
GIMP: GNU Image Manipulation Program
 GTK+ is a set of Graphical User Interface (GUI) tool
 GTK+ is used to build GUI-based X-window system
 What is Glade?
 Glade is an User Interface Builder for GTK+
 Glade is a Visual Programming Tool
Similar to the Visual tool VB, Delphi,…
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Installation of “Glade” on XSBase255
 At the /home/Packages/RPM/ folder, type the command:
rpm –ivh glade-0.6.4-9.i386.rpm
 rpm is the Red-Hat Package Manager
 -i means install
Command: rpm –ivh glade-0.6.4.9.i386.rpm
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MPEG-2 Technologies
MPEG-2 Decoder Implementation
MPEG
 MPEG ( Motion Picture Experts Group)
 Established in 1988
 A working group of ISO/IEC in charge of the development of
standards for coded representation of digital audio and video
 MPEG Standards: System, Video, Audio
 Products
 MPEG-1: Video CD and MP3 are based
 MPEG-2: Digital Television set top boxes and DVD
 MPEG-4: multimedia for the fixed and mobile web
 MPEG-7: for description and search of audio and visual
content
 MPEG-21: the Multimedia Framework
 Reference sites
 http://www.mpeg.org/
 http://www.chiariglione.org/mpeg/
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MPEG System Specifications
 Provide timing information for:
 Buffer management
 Audio/video synchronization
 ...
 Multiplex bit streams of:
 Audio, video, data and control
 Supporting:
 Access control (security)
 Program specific information
 Digital storage control
 ...
 MPEG-2 system applications
 Broadcast digital TV, Cable digital TV, Interactive TV,
DVD, ... etc.
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H.264/AVC MPEG-4 Applications
(資料來源：工研院經資中心 經濟部ITIS計畫，2000、資料整理：MIC)
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MPEG-2 Video Compression
 Topics
 MPEG Coder/Decoder Diagram
 Profiles and Levels
 Frames, Fields, Pictures (I: Intraframe, P: Predicted, B:
Bi-directional)
 I P B Picture Reordering
 Pixel Positioning
 Compression tools
 MPEG 2 Video Data Structures
 MPEG-2 Toturial Web Sites
 http://www.bretl.com/mpeghtml/MPEGindex.htm
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Basic MPEG Diagram
Video
signal
DCT
+
+
Q
VLC
Coded
Macro-Block
Data
-
IQ
Block of
Current
Frame
IDCT
ME
+
Vector
Block of
Previous
Frame
+
BUF
Coded
Macro-Block
Data
+
Frame
Buffer
MC
(a) MPEG encoder block diagram
Decoded Video Signal
VLD
IQ
IDCT
+
Motion Vectors
Frame
Memory
MC
(b) MPEG decoder block diagram
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Mpeg2 Encode Profiling
Operation
% exe time
Motion estimation (dist1)
71%
Discrete cosine transform
9%
Subsampling
2%
Predication
1%
Quantisation
1%
Variable length encoding
1%
Other kernels
14%
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