Summary:
========
包含uboot源代码 （包含的架构有： PPC， ARM， MIPS， etc）
This directory contains the source code for U-Boot,
a boot loader for Embedded boards based on
PowerPC,
ARM,
MIPS
and
several other processors,
可以安装到启动的rom中用来初始化或是测试硬件或是下载/运行程序
which can be installed in a boot ROM and used to
initialize and test the hardware or to download and run application
code
与linux有一些关联，（头文件及linux 内核镜像）
The development of U-Boot is closely related to Linux: some parts of
the source code originate in the Linux source tree, we have some
header files in common, and special provision has been made to
support booting of Linux images
会使u-boot 根据的配置及扩展， 所有的monitor commands 有统一的接口 （方便增减）
Some attention has been paid to make this software easily
configurable and extendable. For instance, all monitor commands are
implemented with the same call interface, so that it's very easy to
add new commands. Also, instead of permanently adding rarely used
code (for instance hardware test utilities) to the monitor, you can
load and run it dynamically.
Status: （目前的状态）
=======
Makefile 中的配置选项是经过测试的， 很多已用到生产上
In general, all boards for which a configuration option exists in the
Makefile have been tested to some extent and can be considered
"working". In fact, many of them are used in production systems.
问题查找
In case of problems see the CHANGELOG and CREDITS files to find out
who contributed the specific port.
Where to get help:
==================
获取帮助
In case you have questions about, problems with or contributions for
U-Boot you should send a message to the U-Boot mailing list at
<u-boot-users@lists.sourceforge.net>. There is also an archive of
previous traffic on the mailing list - please search the archive
before asking FAQ's. Please see
http://lists.sourceforge.net/lists/listinfo/u-boot-users/
Where we come from:
===================
u-boot项目历程：
- start from 8xxrom sources
- create PPCBoot project (http://sourceforge.net/projects/ppcboot)
- clean up code
- make it easier to add custom boards
- make it possible to add other [PowerPC] CPUs
- extend functions, especially:
* Provide extended interface to Linux boot loader
* S-Record download
* network boot
* PCMCIA / CompactFLash / ATA disk / SCSI ... boot
- create ARMBoot project (http://sourceforge.net/projects/armboot)
- add other CPU families (starting with ARM)
- create U-Boot project (http://sourceforge.net/projects/u-boot)
Names and Spelling:
===================
命名与书写：
The "official" name of this project is "Das U-Boot". The spelling
"U-Boot" shall be used in all written text (documentation, comments
in source files etc.). Example:
This is the README file for the U-Boot project.
File names etc. shall be based on the string "u-boot". Examples:
include/asm-ppc/u-boot.h
#include <asm/u-boot.h>
Variable names, preprocessor constants etc. shall be either based on
the string "u_boot" or on "U_BOOT". Example:
U_BOOT_VERSION u_boot_logo
IH_OS_U_BOOT u_boot_hush_start
Versioning:
===========
版本号的构成：
U-Boot uses a 3 level version number containing a version, a
sub-version, and a patchlevel: "U-Boot-2.34.5" means version "2",
sub-version "34", and patchlevel "4".
The patchlevel is used to indicate certain stages of development
between released versions, i. e. officially released versions of
U-Boot will always have a patchlevel of "0".
Directory Hierarchy:
====================
目录结构
- board Board dependent files
- common Misc architecture independent functions
- cpu CPU specific files
--- ...
- disk Code for disk drive partition handling
- doc Documentation (don't expect too much)
- drivers Commonly used device drivers
- dtt Digital Thermometer and Thermostat drivers
- examples Example code for standalone applications, etc.
- include Header Files
- lib_arm Files generic to ARM architecture
- lib_avr32 Files generic to AVR32 architecture
- lib_generic Files generic to all architectures
- lib_i386 Files generic to i386 architecture
- lib_m68k Files generic to m68k architecture
- lib_mips Files generic to MIPS architecture
- lib_nios Files generic to NIOS architecture
- lib_ppc Files generic to PowerPC architecture
- net Networking code
- post Power On Self Test
- rtc Real Time Clock drivers
- tools Tools to build S-Record or U-Boot images, etc.