BootLoader

Introduction

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

Some (informational) commands

BIOS> printenv

BIOS> bdinfo
arch_number = 0x000006A2
env_t       = 0x00000000
boot_params = 0xA0000100
DRAM bank   = 0x00000000
-> start    = 0xA0000000
-> size     = 0x04000000
DRAM bank   = 0x00000001
-> start    = 0xB0000000
-> size     = 0x04000000
ethaddr     = 00:1E:AC:00:10:54
ip_addr     = 192.168.1.10
baudrate    = 115200 bps

BIOS> nand info

Device 0: NAND 256MiB 1,8V 16-bit, sector size 128 KiB

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/apfXX-root"    (to boot Linux over NFS)
 setenv consoledev ttymxc0

• 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 !

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 uboot-rebuild

Binaries

Compiled binary files will be put in the buildroot/output/images/ subdirectory:

• apf9328-u-boot.bin is a binary image file for the apf9328that can be downloaded and flashed from U-Boot itself (see below)
• (Armadeus 5.0) image filenames are respectively for each board apf27-u-boot-nand.bin apf51-u-boot-nand.bin apf28-u-boot.sb

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-u-boot-<version>.h

Autoboot keyed

To stop autoboot with special keys or special word, add following lines in the apfxx-u-boot-<version>.h file :

• after :

#define CONFIG_BOOTDELAY        2
#define CONFIG_ZERO_BOOTDELAY_CHECK

• add :

#define CONFIG_AUTOBOOT_KEYED
#define CONFIG_AUTOBOOT_PROMPT          "autoboot in %d seconds\n",bootdelay
#define CONFIG_AUTOBOOT_STOP_STR        "v"

The autoboot delay will be stopped if «password» given by CONFIG_AUTOBOOT_STOP_STR be entered.

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.

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>run download_uboot

  • With ethernet and a NFS server:

    BIOS> nfs ${loadaddr} ${serverip}:/tftpboot/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: - on the APF9328 board

BIOS> run jffsboot

- on the other APF board

BIOS> run ubifsboot

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

BIOS> printenv bootcmd
bootcmd=run jffsboot
or
bootcmd=run ubifsboot 

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

• NFS boot

BIOS> 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/apfXX-root"

• MMC/SD boot

Your SD should contain a rootfs and a kernel Linux in the /boot directory. see Put your rootfs and Linux kernel on the MMC/SD for more information.

BIOS> run mmcboot

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

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
• http://git.denx.de/?p=u-boot.git;a=blob_plain;f=tools/scripts/dot.kermrc