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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

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

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

    - 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 (and notice how you can ask for help for more than one command at a time):

=> help fli tftp
flinfo - print FLASH memory information

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

tftpboot [loadAddress] [[hostIPaddr:]bootfilename]
5.6. Initialization 1. Abstract 5.8. The First Power-On
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