Skip to main content.

5.7. Initial Steps

In the default configuration, U-Boot operates in an interactive mode which provides a simple command line-oriented user interface using a serial console on port UART1.

In the simplest case, this means that U-Boot shows a prompt (default: =>) when it is ready to receive user input. You then type a command, and press enter. U-Boot will try to run the required action(s), and then prompt for another command.

To see a list of the available U-Boot commands, you can type help (or simply ?). This will print a list of all commands that are available in your current configuration. [Please note that U-Boot provides a lot of configuration options; not all options are available for all processors and boards, and some options might be simply not selected for your configuration.]

=>
=> hel

With the command help <command> you can get additional information about most commands:

=> help tftpboot
tftpboot - boot image via network using TFTP protocol

Usage:
tftpboot [loadAddress] [[hostIPaddr:]bootfilename]
=> help setenv printenv
setenv - set environment variables

Usage:
setenv name value ...
    - set environment variable 'name' to 'value ...'
setenv name
    - delete environment variable 'name'
printenv - print environment variables

Usage:
printenv
    - print values of all environment variables
printenv name ...
    - print value of environment variable 'name'
=>

Most commands can be abbreviated as long as the string remains unambiguous:

=> help fli tftp
flinfo - print FLASH memory information

Usage:
flinfo
    - print information for all FLASH memory banks
flinfo N
    - print information for FLASH memory bank # N
tftpboot - boot image via network using TFTP protocol

Usage:
tftpboot [loadAddress] [[hostIPaddr:]bootfilename]
=>
5.6. Initialization 1. Abstract 5.8. The First Power-On
Prev Home Next