1. Computer System Laboratory
Lab4 Bootloader

2. Experimental Goal
Build the U-Boot and use JTAG to download U-Boot to the target board without bootloader
Lab4
2019/4/20

3. Environment Host System Build System Target System Software
Windows XP/Ubuntu 8.04
Build System
Ubuntu 8.04
Target System
XScale PXA270
Software
DENX U-Boot source code
You can download all the source codes from
RSWiki CSL Course Software
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2019/4/20

4. Bootloader Concept A typical flow when booting a computer Bootloader
Load BIOS and self check
Execute bootloader
Load kernel and filesystem
Initialize hardware elements …
Bootloader
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2019/4/20

5. Bootloader Concept (Cont.)
All CPUs will execute the first instruction from a specified address when power on
ROM, EEPROM, Flash memory, etc
ARM system will execute from 0x
Typical space allocation
Lab4
2019/4/20

6. System Memory Layout memory layout 0x00000000 0xa0000000 U-Boot 3
Linux kernel 0x
0xa
U-Boot 2
Linux File System 0x
0xa3f80000
U-Boot 1 0x
0xa
Flash memory
RAM
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2019/4/20

7. Bootloader Examples Bootloader highly dependents on architecture
Some popular bootloaders
LILO, GRUB
You can see /boot/grub/menu.lst for the settings in Ubuntu
Windows Boot Manager
You can see the settings in C:\boot.init in XP
U-Boot
We will use U-Boot for PXA270 (ARM architecture)
Lab4
2019/4/20

8. Introduction to U-Boot
Das U-Boot (Universal Bootloader) is an open source, primary bootloader used in embedded system
It is available for a number of different computer architectures, including PPC, ARM, MIPS, x86
The current name Das U-Boot adds a German definite article as a pun to the German word for “submarine”
~ from Wikipedia
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2019/4/20

9. U-Boot Compilation Step1 : download patched source code
Step2 : extract source code
% tar –zxvf mt-u-boot tar.gz
Step3 : check Lab1’s arm-elf toolchain path in PATH
Tips
The include/configs/ directory under U-Boot source directory contains one configuration file for each supported board
It defines the CPU type, the peripherals and their configuration, the memory mapping, the U-Boot features that should be compiled in, etc
Lab4
2019/4/20

10. U-Boot Compilation (Cont.)
Step4 : compile U-Boot
U-Boot must be configured before being compiled, i.e. make <target board>_config, where <target board> is the name of the configuration file in include/configs/, without the .h
% cd u-boot-1.1.2
% ./mt-crpxa270_config.sh
The resulting u-boot.bin is the bootloader we want
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2019/4/20

11. Download U-Boot to Target Board
Step1 : open Domingo (refer to Lab3)
Step2 : load u-boot.bin (the address of SDRAM lies within the range 0xa xa )
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2019/4/20

12. Download U-Boot to Target Board (Cont.)
Step3 : change the PC value in registers
Step4 : open Serial Console
Step5 : click Debug  Free Go
Hit any key to stop U-Boot autoboot
Step6 : use “flinfo” command to check if U-Boot can control flash memory
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2019/4/20

13. Transfer File via TFTP
Step1 : openTFTP Server (Windows version, refer to Lab2)
Step2 : change Host IP address (according to your U-Boot setting, use “printenv serverip” command in U-Boot shell)
Step3 : copy u-boot.bin to TFTP Server’s root directory
Step4 : download U-Boot via Ethernet cable
$ tftp a u-boot.bin
Tip
U-Boot has a built-in TFTP client
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2019/4/20

14. Copy to Flash memory Step1 : disable flash write protection
$ protect off 0 7ffff
Step2 : erase the specified range of bytes
$ erase 0 7ffff
Step3 : copy U-Boot to reset address
$ cp.b a
Step4 : change environment variable (optional)
$ setenv ipaddr <target-system-ip>
$ setenv serverip <host-system-ip>
$ saveenv
Now, you can abandon Domingo, remember to change Host System IP if you change environment variable
Lab4
2019/4/20

15. Configure U-Boot
If you want to change U-Boot default environment, modify the specified file and recompile U-Boot
% cd u-boot-1.1.2
% vim include/configs/Create_XScale_PXA270.h
Host System IP : CONFIG_SERVERIP
Target System IP : CONFIG_IPADDR
Boot arguments : CONFIG_BOOTARGS
Boot command : CONFIG_BOOTCOMMAND
U-Boot delay : CONFIG_BOOTDELAY (do not set to 0!)
Linux kernel start command : CONFIG_LINUX
Tip
The U-Boot environment variable ‘bootargs’ is used to hold the parameter options passed to the Linux kernel, as the kernel’s command line parameters
Lab4
2019/4/20

16. Exercise
Use U-Boot to automatically start last week’s test program after reset
This time, let LED really be blinking in your own way, such as blinking once every number of your group second.
Tip
Use “setenv bootcmd” command to modify U-Boot boot command
Use U-Boot “go <addr>” to start program at address ‘addr’
For more information about LED control register, please refer to Create XScale-PXA270 User’s Guide, 4.3.2
Lab4
2019/4/20