WIN Enterprises PL-80720, Руководство пользователя

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Copyright © WIN Enterprises, Inc. All Rights Reserved.
Dec., 2014
Chapter 4. U-Boot Reference Manual
Chapter 4. U-Boot Reference Manual
The ROM chip of your PL-80720 board is configured with a customized
Basic Input/Output System (U-Boot). The U-Boot is a set of permanently
recorded program routines that give the system its fundamental operational
characteristics. It also tests the computer and determines how the
computer reacts to instructions that are part of the programs.
4.1 The boot process
After power-up or reset, the processor loads the U-Boot boot loader in
several steps.
●
The processor does these steps:
Executes a primary bootstrap that configures the interrupt and
exception vectors, clocks, and SDRAM
Decompresses the U-Boot code from flash to RAM
Passes execution control to the U-Boot
●
U-Boot does these steps:
Configures the Ethernet MAC address, flash, and, serial console
Loads the settings stored as environment variables in flash
After a few seconds (a length of time you can program), automatically
boots the pre-installed kernel
To stop the automatic booting (autoboot) of the pre-installed kernel, send a
character to the serial port by pressing a key from the serial console
connected to the target. If U-Boot is stopped, it displays a command line
console (also called monitor).