Difference between revisions of "BootLoader"

Revision as of 10:41, 29 October 2009

Introduction

This page describe the U-Boot installation/usage in the Armadeus context.

Build U-Boot

Build process is now part of the Armadeus automated build (see Install Armadeus software). To only build U-Boot you can launch:

 $ make u-boot-clean
 $ make u-boot

Binaries

Compiled binary files will be put in the buildroot/binaries/apfxx/ subdirectory:

• apfxx-u-boot.bin is a binary image file that can be downloaded and flashed from U-Boot itself (see below)
• apf9328-u-boot-brec is a boostrap record file compatible with the Freescale bootstrap inside the i.MXL (only when compiling for APF9328).

Customizing

• U-Boot build is done by the following Makefiles:
  • buildroot/target/u-boot/Makefile.in (generic part)
  • buildroot/target/device/armadeus/u-boot/u-boot.mk (target specific part)

• Configuration file (target specific) used to customize the build is:
  • buildroot/target/device/armadeus/apfxx/apfxx.h

Install or restore from scratch (board bricked)

If your Armadeus board doesn't boot anymore (flash content erased or dammaged), you will have to use the bootstrap mode of the i.MX.
In that case the uboot_recover python script is used to flash a new U-Boot version; this tool is located in the armadeus/software/uboot_recover/ folder of the Armadeus project tree.
Take a look a the INSTALL file the first time you want to use the recover tool.
Remark: the serial port must support a baud rate of 57600 bps per second.

Modify your environment variables

• There is a set of variables you can customize to your needs. The command printenv show you most of them and their current state. Use the command setenv to change one of these variable. For instance:

 BIOS> setenv ipaddr 192.168.0.10

• Use the command saveenv to save the state of your environment variables in flash memory.
• In order to use network features with U-Boot you have to set the network environment variables:

 setenv netmask 255.255.255.0                (default value should be fine in most situations)
 setenv ipaddr 192.168.0.10
 setenv serverip 192.168.0.2                 (the IP address of your TFTP Host server to download image files)
 setenv rootpath "/tftpboot/apf9328-root"    (to boot Linux over NFS)

• You can use the dhcp command to configure these variable from your DHCP server. Probably you will have to adjust the serverip variable manually.

 BIOS> dhcp
 dm9000 i/o: 0x15c00000, id: 0x90000a46
 MAC: 00:0e:32:00:00:01
 operating at 100M full duplex mode
 BOOTP broadcast 1
 DHCP client bound to address 192.168.0.10
 BIOS>setenv serverip 192.168.0.2
 BIOS>saveenv

• Do not forget to save your changes in flash with saveenv to have them available at power up !

Update U-Boot

There are 2 steps to update U-Boot:

• 1] Load the new U-Boot code in RAM (You can use the following commands to download U-boot):
  • With ethernet and a TFTP server:

    BIOS> tftpboot ${loadaddr} apfxx-u-boot.bin

  • With ethernet and a NFS server:

    BIOS> nfs ${loadaddr} ${serverip}:/nfs_path_to_buildroot/apfxx-u-boot.bin

  • With the kermit and a serial line:

BIOS> loadb ${loadaddr}
    <CTRL> <ALT GR> \ then c
    send /path_to_tftpboot/apfxx-u-boot.bin
    ...>>> LOADING IN PROGRESS <<<...
    c

• 2] Transfer code from RAM to FLASH memory (there is a simple U-Boot command/script to do that):

 BIOS> run flash_uboot

Advanced Linux boot

The command "boot" is the common way to run Linux from flash memory. This command is equivalent to the macro:

   run jffsboot

This is the default command stored the U-Boot variable: bootcmd.

   bootcmd=run jffsboot

U-Boot also supports the commands to boot from a network or a sd/mmc card.

• NFS boot

   run nfsboot

This command boots Linux rootfs from a NFS server. Change the U-Boot variables serverip and rootpath to fit with your host PC.

   serverip=192.168.0.2
   rootpath="/tftpboot/apf9328-root"

• MMC/SD boot

   run mmcboot

This command boots Linux rootfs from an sd/mmc memory card. Adapt the variables: mmcroot and mmcrootfstype to your card's boot partition type.

   mmcroot=/dev/mmcblk0p1
   mmcrootfstype=ext2

Customize the flash memory organization

TBD

Installing Target software from U-Boot

Target Software Installation

Booting Linux

The Install Armadeus software on target provide some information to install linux on Armadeus board

Customize Linux boot mode

Typical Kermit (.kermrc) config file

set line /dev/ttyS0
set speed 115200
set carrier-watch off
set handshake none
set flow-control none
robust
set file type bin
set file name lit
set rec pack 1000
set send pack 1000
set window 5
set transmit linefeed on

Links

• http://www.denx.de/wiki/DULG/Manual