1. Lab 4 Department of Computer Science and Information Engineering National Taiwan University Lab4 - Bootloader 2014/10/14/ 13 1

2. Lab 4 Department of Computer Science and Information Engineering National Taiwan University  Learn how to build U-Boot bootloader for PXA270. 2014/10/14/ 13 2

3. Lab 4 Department of Computer Science and Information Engineering National Taiwan University  Host System  Windows XP  Build System  VirtualBox + Ubuntu 8.04  Target System  Creator XScale PXA270  Software  DENX U-Boot  You can find all software on RSWiki CSL Course Software.RSWiki CSL Course Software 2014/10/14/ 13 3

4. Lab 4 Department of Computer Science and Information Engineering National Taiwan University  A typical flow when booting a computer.  Load BIOS and do hardware self-test.  Execute bootloader in master boot record (MBR) which is the first sector of disk.  Load kernel and root filesystem.  Initialize hardware.  …  When a computer is powered on, CPU will execute the first instruction from a specified address:  ROM, EEPROM, Flash memory, etc.  In ARM system, the address usually is 0x00000000.  In other words, bootloader is usually located at 0x00000000.  Typical space allocation: 2014/10/14/ 13 4

5. Lab 4 Department of Computer Science and Information Engineering National Taiwan University  Bootloader highly depends on architecture.  Some popular bootloaders:  LILO, GRUB, GRUB2  You can see /boot/grub/menu.lst for the settings in Ubuntu 8.04.  Windows Boot Manager  You can see the settings in C:\boot.init in Windows XP.  U-Boot  We will use U-Boot for PXA270 (ARM architecture). 2014/10/14/ 13 5

6. Lab 4 Department of Computer Science and Information Engineering National Taiwan University  Das U-Boot (Universal Bootloader) is an open source, primary bootloader used in embedded systems.  It is available for a number of different computer architectures, including PPC, ARM, MIPS, x86, etc.  The current name Das U-Boot adds a German definite article as a pun to the German word for “submarine”. 2014/10/14/ 13 6 Reference: Das U-Boot, http://en.wikipedia.org/wiki/Das_U-Boothttp://en.wikipedia.org/wiki/Das_U-Boot

7. Lab 4 Department of Computer Science and Information Engineering National Taiwan University  Step 1: download the patched source codes of U-Boot (mt-u-boot- 1.1.2.tar.gz) in Ubuntu 8.04.mt-u-boot- 1.1.2.tar.gz  Step 2: extract source codes.  Step 3: please check the path of toolchain arm-elf-* is in PATH.  The toolchain arm-elf-* will be used in the compilation.  Tips:  The include/configs/ directory under U-Boot source directory contains configuration files for supported boards.  It defines the CPU type, the peripherals and their configuration, the memory mapping, the U-Boot features that should be compiled in, etc.  For instance of PXA270, U-boot will be copied to 0xA3F80000 when it is loaded by CPU and it uses 0x00020000 to 0x0003FFFF as the boot parameters. 2014/10/14/ 13 7

8. Lab 4 Department of Computer Science and Information Engineering National Taiwan University  Step 4: compile U-Boot.  U-Boot must be configured for the target board before being compiled, i.e., make _config, where is the name of the configuration file in include/configs/, without the “.h ”.  E.g., Create_XScale_PXA270 is for our target board.  % cd u-boot-1.1.2  % make mrproper  This command often uses to clean all the object files and configurations.  You can see Makefile and check what it has done.  % make Create_XScale_PXA270_config  % make  The resulting u-boot.bin is the bootloader we want so that we can copy it to PXA270. 2014/10/14/ 13 8

9. Lab 4 Department of Computer Science and Information Engineering National Taiwan University 2014/10/14/ 13 9 0xA0000000 0xA4000000 RAM U-Boot Flash 0x00000000 0x00040000 0x00080000 diag 0x00480000 0x01380000 Linux kernel 1 Root Filesystem 0x00020000 U-Boot parameters 0x02000000 0x01C00000 Linux kernel 2U-Boot 0xA3F80000

10. Lab 4 Department of Computer Science and Information Engineering National Taiwan University  If you want to change default configuration for PXA270, you can modify the specified files and recompile U-Boot.  % cd u-boot-1.1.2  % nano include/configs/Create_XScale_PXA270.h  CONFIG_SERVERIP: host system IP.  CONFIG_IPADDR: target system IP.  CONFIG_BOOTARGS: boot arguments.  CONFIG_BOOTCOMMAND: boot command.  CONFIG_BOOTDELAY: U-Boot delay (do not set to 0!).  CONFIG_LINUX: Linux kernel start command.  etc.  Tips:  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. 2014/10/14/ 13 10

11. Lab 4 Department of Computer Science and Information Engineering National Taiwan University  Step 1: please modify the boot command in U-Boot.  CONFIG_BOOTCOMMAND = “ run linux ”  CONFIG_LINUX = “ bootm 80000 ”  Step 2: please try to change the command prompt and display with your group id. 2014/10/14/ 13 11

12. Lab 4 Department of Computer Science and Information Engineering National Taiwan University  Step 3: copy the uImage provided in lab3 to flash address 0x01C00000.  The erased end address is 0x1FFFFFF (32 sectors).  Step 4: compile your U-Boot and copy to flash address 0x00000000.  Make sure you also erase the boot parameters sector ( 0x00020000 to 0x0003FFFF ), or your modified settings could not work.  Step 5: reset PXA270 and then you will see new configuration.  Try to do some settings so that you can choose which to boot on, the two Linux kernels,or the program diag. 2014/10/14/ 13 12

13. Lab 4 Department of Computer Science and Information Engineering National Taiwan University  Show your own command prompt in U-Boot.  Show that you can choose what to boot on, and it is as simple as possible.  Please hand in your lab report to the FTP.  Server: 140.112.90.174  Username: csl2014  Password: csl2014HomeWork  Directory: lab4  Please use this format for filename: “G# Ver#”, where G# is your group id and Ver# is revision version number.  E.g., G1 Ver2 2014/10/14/ 13 13