V2020.01 U-Boot shell

The U-Boot shell provides the ability to run commands directly on the console, and includes commands for modification and saving of the environment (discussed further below).

By default, there is only one way to enter the shell: Pressing the esc key twice within a 1-second window immediately at power-on/reset will bring you to the U-Boot shell prompt. This behavior can be modified by setting the U-Boot environment variable bootdelay. If modified (and saved), it will force the timeout for pressing the esc key to be however many seconds the variable is set to. If it is set to 0, then the esc prompt is skipped, and if set to -1, the sequence will always stop in U-Boot.

Note:

Use caution when setting bootdelay! A value of 0 means it is no longer possible to enter the U-Boot shell. We do not recommend using bootdelay in this manner, as we do not support it. Be sure to read the U-Boot Documentation for further details U-Boot Documentation.

When stopped in U-Boot, booting can be resumed by simply typing boot or run bootcmd.