Copyright ©
WIN Enterprises, Inc. All Rights Reserved.
Dec., 2014
Chapter 4. U-Boot Reference Manual
36
4.11.3 System variables
U-Boot uses several built-in variables:
4.11.3.1 Common system variables
Variable
Description
autoload
If set to "no" (or any string beginning with 'n'), the
bootp
, or
dhcp
command performs a configuration lookup from the BOOTP / DHCP
server but does not try to load any image using TFTP.
autostart
If set to "yes", an image loaded using the
bootp
,
dhcp
or
tftpboot
commands is automatically started (by internally calling the
bootm
command).
baudrate
The baud rate of the serial connection.
bootcmd
Defines a command string that is automatically executed when the
initial countdown is not interrupted.
Executed only when the
bootdelay
variable is also defined.
bootdelay
Seconds to wait before running the automatic boot process in
bootcmd
.
bootfile
Name of the default image to load with TFTP.
filesize
Contains the size of the last file transferred by TFTP or USB.
fileaddr
The RAM address where the last file transferred by TFTP was placed.
stdin
Standard input system.
stdout
Standard output system.
stderr
Standard error output system.
verify
If set to 'n' or 'no,' disables the checksum calculation over the complete
image in the
bootm
command to trade speed for safety in the boot
process. Note that the header checksum is still verified.
ipaddr
IP address of the target's Ethernet interface.
netmask
Subnet mask of Ethernet interface.
gatewayip
IP address used as network gateway.
serverip
IP address of the host PC (for remote connections like TFTP transfers).
