Kontron AT8404 - Manual (Page 65)

Software Description
52 AT8404 User Guide
www.kontron.com
4.2.2 Bootloader shell options
The boot process can be interrupted by entering the bootstopkey “stop”. This will open a bootloader shell
session.
“?” provides a list of possible commands, “printenv” provides a list of environment settings.
The bootloader shell can be used to customize boot options and system startup.
For additional information about the bootloader and the tools to customize the u-boot, refer to:
http://sourceforge.net/projects/u-boot/
CAUTION
Changing bootloader environment variables must be taken very care-
fully. It will change system behaviour.
Table 4-3: Bootloader environment variables
Name Description
ethaddr
contains the default base MAC address of the board. If this is not set, the MAC address
from VPD is used.
bootcmd
This variable defines a command string that is automatically executed when the initial
countdown is not interrupted.
This command is only executed when the variable bootdelay is also defined!
bootcmdflash
contains the standard startup script for loading OS image from flash partition com-
mand.
bootcmdnet contains the standard startup script for loading OS image from network
bootcmdprd contains the standard startup script for use during board production
bootdelay
After reset, U-Boot will wait this number of seconds before it executes the contents of
the bootcmd variable. During this time a countdown is printed, which can be inter-
rupted by pressing any key.
Set this variable to 0 boots without delay. Be careful: depending on the contents of
your bootcmd variable, this can prevent you from entering interactive commands
again forever!
Set this variable to -1 to disable autoboot.
bootsetup
checks for the boot image number detected on startup and sets the OS load address
respectively.
It is strongly recommended not to change this variable.
bootsource
When the standard boot sequence is used, contains the boot source, either flash, net,
prd to select the respective boot sequence to activate. It is only used when bootcmd
contains the default startup script, which may be overridden by the user.
default: flash
ethact
Current network interface used by network commands (bootp, tftpboot et al)
default: ppc_4xx_eth0
loadaddr
Default load address for network transfers. This is used as a temporary storage for
netbooting and firmware updates.
default: 0x8000000
early_cmd
contains the standard script for setting up the pBMWD watchdog after POST has fin-
ished, but before the bootstopkey is checked