TP-Link TL-WR703N 路由器的 U-Boot

TP-Link TL-WR703N 路由器的 U-Boot：

在 TP-Link TL-WR703N 路由器固件（Firmware）是存放在機內的 Flash Memory，在 703N 的原廠 Flash Memory 容量是 4MB，而這 4MB Flash 內容包括了 U-Boot、fw 和 art 程式，每一個固件內的程式都是負責不同的功能，這 4MB 的程式就好像我們日常用到的 PC 電腦一樣，可以說路由器就是一部超迷你電腦，U-Boot 就像電腦的 BIOS （Basic Input/Output System）， FW 就像電腦的作業系統，ART 就像電腦的驅動程式。

703N 4M Flash Memeory 路由器固件：

	Flash Start地址	Flash End 地址	TTL Start 地址	TTL End 地址	長度
U-Boot	0x000000	0x01FFFF	0x9F000000	0x9F01FFFF	128kB（0x20000）
FW	0x020000	0x3DFFFF	0x9F020000	0x9F3DFFFF	3840kB（0x3c0000）
ART	0x3F0000	0x3FFFFF	0x9F3F0000	0x9F3FFFFF	64kB（0x10000）

703N 8M Flash Memeory 路由器固件：

	Flash Start地址	Flash End 地址	TTL Start 地址	TTL End 地址	長度
U-Boot	0x000000	0x01FFFF	0x9F000000	0x9F01FFFF	128kB（0x20000）
FW	0x020000	0x7DFFFF	0x9F020000	0x9F7DFFFF	7936kB（0x7c0000）
ART	0x7F0000	0x7FFFFF	0x9F7F0000	0x9F7FFFFF	64kB（0x10000）

U-Boot 使用少量的閃存存儲空間（長度為128KB = 0x20000），通常在同一個分區存儲在存儲一些重要的配置參數。

U-Boot Common Variables：

Variable	Description
autoload	if set to no (or any string beginning with 'n'), the rarpb, bootp or dhcp commands will perform only a configuration lookup from the BOOTP / DHCP server, but not try to load any image using TFTP.
autostart	if set to yes, an image loaded using the rarpb, bootp, dhcp, tftp, disk, or docb commands will be automatically started (by internally calling the bootm command).
baudrate	a decimal number that selects the console baudrate (in bps).
bootargs	The contents of this variable are passed to the Linux kernel as boot arguments (aka "command line").
bootcmd	This variable defines a command string that is automatically executed when the initial countdown is not interrupted. This command is only executed when the variable bootdelay is also defined!
bootdelay	After reset, U-Boot will wait this number of seconds before it executes the contents of the bootcmd variable. During this time a countdown is printed, which can be interrupted by pressing any key. Set this variable to 0 boot without delay. Be careful: depending on the contents of your bootcmd variable, this can prevent you from entering interactive commands again forever! Set this variable to -1 to disable autoboot.
bootfile	name of the default image to load with TFTP
ethaddr	Ethernet MAC address for first/only ethernet interface (eth0 in Linux). This variable can be set only once (usually during manufacturing of the board). U-Boot refuses to delete or overwrite this variable once it has been set.
ipaddr	IP address; needed for tftp command
loadaddr	Default load address for commands like tftp or loads
serverip	TFTP server IP address; needed for tftp command.
silent	If the configuration option CONFIG_SILENT_CONSOLE has been enabled for your board, setting this variable to any value will suppress all console messages. Please see silent booting for details.
verify	If set to n or no disables the checksum calculation over the complete image in the bootm command to trade speed for safety in the boot process. Note that the header checksum is still verified.

703N 4M Flash Memeory U-Boot 地址：

Start	Offset	Description
0	0x00000000	Flash Start, U-Boot code data (64kB)
+64kB	0x00010000	Start of block with MAC address
	0x0001FC00	MAC address (6 byte)
	0x0001FD00	TP-Link router model number
	0x0001FE00	WPS pin (8 bytes)
+128kB	0x00020000	Firware start