U-boot下载与烧写
使用U-boot将映像文件烧写到板上的Flash，一般步骤是：
（1）通过网络、串口、U盘、SD卡等方式将文件传输到SDRAM；
（2）使用Nand Flash或Nor Flash相关的读写命令将SDRAM中的数据烧入Flash。
下面是烧写范例：
如果使用 SD卡和U盘形式更新U-boot，那么首先SD卡和U盘中必须有FAT32文件系统，并在里面存放了u-boot.bin 文件。
1) 通过SD卡烧入Nand Flash：
[u-boot@MINI2440]# mmc init
mmc: Probing for SDHC ...
mmc: SD 2.0 or later card found
trying to detect SD Card...
Manufacturer:
0x00, OEM "roduct name:
"
", revision 0.0
Serial number:
7864775
Manufacturing date: 11/2006
CRC:
0x4f, b0 = 1
READ_BL_LEN=6, C_SIZE_MULT=7, C_SIZE=4095
size = 0
SD Card detected RCA: 0x2 type: SD
mmc1 is available
[u-boot@MINI2440]# fatload mmc 1 0x30008000 u-boot.bin
reading u-boot.bin
256220 bytes read
[u-boot@MINI2440]# nand erase 0 0x40000
NAND erase: device 0 offset 0x0, size 0x40000
Erasing at 0x2000000000004 --
0% complete.
OK
[u-boot@MINI2440]# nand write 0x30008000 0 0x40000
NAND write: device 0 offset 0x0, size 0x40000
Writing at 0x2000000020000 -- 100% is complete. 262144 bytes written: OK
2) 通过U盘烧入Nor Flash：
[u-boot@MINI2440]# usb start
(Re)start USB...
USB:
scanning bus for devices... 2 USB Device(s) found
scanning bus for storage devices... 1 Storage Device(s) found
[u-boot@MINI2440]# usb storage
Device 0: Vendor: Kingston Rev: PMAP Prod: DT 101 II
Type: Removable Hard Disk
Capacity: 3875.0 MB = 3.7 GB (7936000 x 512)
[u-boot@MINI2440]# usb part 0
print_part of 0
Partition Map for USB device 0
--
Partition Type: DOS
Partition
Start Sector
Num Sectors
Type
4
63
7935937
c
[u-boot@MINI2440]# fatload usb 0:4 0x30008000 u-boot.bin
reading u-boot.bin
........................
256220 bytes read
[u-boot@MINI2440]# protect off all
Un-Protect Flash Bank # 1
[u-boot@MINI2440]# erase 0x0 0x3ffff
Erasing sector
0 ... ok.
Erasing sector
1 ... ok.
Erasing sector
2 ... ok.
Erasing sector
3 ... ok.
Erased 4 sectors
[u-boot@MINI2440]# cp.b 0x30008000 0x0
0x3ffff
Copy to Flash... done
3) 通过TFTP服务烧入Nand Flash：
[u-boot@MINI2440]# tftpboot 0x30008000 192.168.1.100:zImage.img
dm9000 i/o: 0x20000300, id: 0x90000a46
DM9000: running in 16 bit mode
MAC: 08:08:11:18:12:27
operating at 100M full duplex mode
Using dm9000 device
TFTP from server 192.168.1.100; our IP address is 192.168.1.101
Filename 'zImage.img'.
Load address: 0x30008000
Loading: T
##################
done
Bytes transferred = 256220 (3e8dc hex)
[u-boot@MINI2440]# nand erase 0 0x40000
NAND erase: device 0 offset 0x0, size 0x40000
Erasing at 0x2000000000004 --
0% complete.
OK
[u-boot@MINI2440]# nand write 0x30008000 0 0x40000
NAND write: device 0 offset 0x0, size 0x40000
Writing at 0x2000000020000 -- 100% is complete. 262144 bytes written: OK
4) 通过NFS 服务烧入Nand Flash：
[u-boot@MINI2440]# nfs 30008000 192.168.1.100:/home/tekkaman/development/share/u-boot.bin
dm9000 i/o: 0x20000300, id: 0x90000a46
DM9000: running in 16 bit mode
MAC: 08:08:11:18:12:27
operating at 100M full duplex mode
Using dm9000 device
File transfer via NFS from server 192.168.1.100; our IP address is 192.168.1.101
Filename '/home/tekkaman/development/share/u-boot.bin'.
Load address: 0x30008000
Loading: ###################################################
done
Bytes transferred = 256220 (3e8dc hex)
[u-boot@MINI2440]# nand erase 0 0x40000
NAND erase: device 0 offset 0x0, size 0x40000
Erasing at 0x2000000000004 --
0% complete.
OK
[u-boot@MINI2440]# nand write 0x30008000 0 0x40000
NAND write: device 0 offset 0x0, size 0x40000
Writing at 0x2000000020000 -- 100% is complete. 262144 bytes written: OK
内核引导
内核的引导步骤如下：
（1）用U-boot的mkimage工具处理内核映像zImage。
（2）通过网络、串口、U盘、SD卡等方式将处理过的内核映像传输到SDRAM的一定位置（一般使用0x30008000）
（3）然后使用”bootm"等内核引导命令来启动内核。
为什么要用U-boot的mkimage工具处理内核映像zImage？
因为在用bootm命令引导内核的时候，bootm需要读取一个64字节的文件头，来获取这个内核映象所针对的CPU体系结构、OS、加载到内存中的位置、在内存中入口点的位置以及映象名等等信息。这样bootm才能为OS设置好启动环境，并跳入内核映象的入口点。而mkimage就是添加这个文件头的专用工具。具体的实现请看U-boot中bootm的源码和mkimage的源码。
mkimage工具的使用：
参数说明：
-A 指定CPU的体系结构，可用值有：alpha、arm
、x86、ia64、mips、mips64、ppc 、s390、sh、sparc 、sparc64、m68k等
-O 指定操作系统类型，可用值有：openbsd、netbsd、freebsd、4_4bsd、linux、svr4、esix、solaris、irix、sco、dell、ncr、lynxos、vxworks、psos、qnx、u-boot、rtems、artos
-T 指定映象类型，可用值有：standalone、kernel、ramdisk、multi、firmware、script、filesystem
-C 指定映象压缩方式，可用值有：
none
不压缩(一般使用这个，因为zImage是已经被bzip2压缩过的自解压内核)
gzip 用gzip的压缩方式
bzip2 用bzip2的压缩方式
-a 指定映象在内存中的加载地址，映象下载到内存中时，要按照用mkimage制作映象时，这个参数所指定的地址值来下载
-e
指定映象运行的入口点地址，这个地址就是-a参数指定的值加上0x40（因为前面有个mkimage添加的0x40个字节的头）
-n
指定映象名
-d 指定制作映象的源文件
以下是制作内核映像的命令示例：
mkimage -n 'tekkaman' -A arm -O linux -T kernel -C none -a 0x30008000 -e 0x30008040 -d zImage zImage.img
以下是使用范例：
1) 通过SD卡引导内核：
首先SD卡中必须有FAT32文件系统，并在里面存放了处理过的内核映像文件。
[u-boot@MINI2440]# mmc init
mmc: Probing for SDHC ...
mmc: SD 2.0 or later card found
trying to detect SD Card...
Manufacturer:
0x00, OEM "roduct name:
"
", revision 0.0
Serial number:
7864775
Manufacturing date: 11/2006
CRC:
0x4f, b0 = 1
READ_BL_LEN=6, C_SIZE_MULT=7, C_SIZE=4095
size = 0
SD Card detected RCA: 0x2 type: SD
mmc1 is available
[u-boot@MINI2440]# fatload mmc 1 30008000 zImage.img
reading zImage.img
2277540 bytes read
[u-boot@MINI2440]# bootm 30008000
## Booting kernel from Legacy Image at 30008000 ...
Image Name:
tekkaman
Created:
2010-03-29
12:59:51 UTC
Image Type:
ARM Linux Kernel Image (uncompressed)
Data Size:
2277476 Bytes =
2.2 MB
Load Address: 30008000
Entry Point:
30008040
Verifying Checksum ... OK
XIP Kernel Image ... OK
OK
Starting kernel ...
Uncompressing Linux... done, booting the kernel.
Linux version 2.6.33.1 (tekkaman@MAGI-Linux) (gcc version 4.3.2 (crosstool-NG-1.6.1-tekkaman) ) #5 Mon Mar 29 20:58:50 CST 2010
CPU: ARM920T [41129200] revision 0 (ARMv4T), cr=c0007177
CPU: VIVT data cache, VIVT instruction cache
Machine: MINI2440
（略）
2) 通过TFTP服务引导内核:
[u-boot@MINI2440]# tftpboot 0x30008000 192.168.1.100:zImage.img
dm9000 i/o: 0x20000300, id: 0x90000a46
DM9000: running in 16 bit mode
MAC: 08:08:11:18:12:27
operating at 100M full duplex mode
Using dm9000 device
TFTP from server 192.168.1.100; our IP address is 192.168.1.101
Filename 'zImage.img'.
Load address: 0x30008000
Loading: T #################################################################
#################################################################
##########################
done
Bytes transferred = 2277540 (22c0a4 hex)
[u-boot@MINI2440]# bootm 30008000
## Booting kernel from Legacy Image at 30008000 ...
Image Name:
tekkaman
Created:
2010-03-29
12:59:51 UTC
Image Type:
ARM Linux Kernel Image (uncompressed)
Data Size:
2277476 Bytes =
2.2 MB
Load Address: 30008000
Entry Point:
30008040
Verifying Checksum ... OK
XIP Kernel Image ... OK
OK
Starting kernel ...
Uncompressing Linux... done, booting the kernel.
Linux version 2.6.33.1 (tekkaman@MAGI-Linux) (gcc version 4.3.2 (crosstool-NG-1.6.1-tekkaman) ) #5 Mon Mar 29 20:58:50 CST 2010
CPU: ARM920T [41129200] revision 0 (ARMv4T), cr=c0007177
CPU: VIVT data cache, VIVT instruction cache
Machine: MINI2440
（略）
3) 通过NFS服务引导内核：
[u-boot@MINI2440]# nfs 30008000 192.168.1.100:/home/tekkaman/development/share/zImage.img
dm9000 i/o: 0x20000300, id: 0x90000a46
DM9000: running in 16 bit mode
MAC: 08:08:11:18:12:27
operating at 100M full duplex mode
Using dm9000 device
File transfer via NFS from server 192.168.1.100; our IP address is 192.168.1.101
Filename '/home/tekkaman/development/share/zImage.img'.
Load address: 0x30008000
Loading: #################################################################
done
Bytes transferred = 2277540 (22c0a4 hex)
[u-boot@MINI2440]# bootm 30008000
## Booting kernel from Legacy Image at 30008000 ...
Image Name:
tekkaman
Created:
2010-03-29
12:59:51 UTC
Image Type:
ARM Linux Kernel Image (uncompressed)
Data Size:
2277476 Bytes =
2.2 MB
Load Address: 30008000
Entry Point:
30008040
Verifying Checksum ... OK
XIP Kernel Image ... OK
OK
Starting kernel ...
Uncompressing Linux... done, booting the kernel.
Linux version 2.6.33.1 (tekkaman@MAGI-Linux) (gcc version 4.3.2 (crosstool-NG-1.6.1-tekkaman) ) #5 Mon Mar 29 20:58:50 CST 2010
CPU: ARM920T [41129200] revision 0 (ARMv4T), cr=c0007177
CPU: VIVT data cache, VIVT instruction cache
Machine: MINI2440
（略）
4) 通过Nand Flash引导内核：
首先要将处理过的内核映像文件烧入Nand Flash的一定位置（由内核分区表决定）。以后每次启动时用Nand Flash的读取命令先将这个内核映像文件读到内存的一定位置（由制作内核映像时的-a参数决定），再使用bootm命令引导内核。
内核映像文件的烧入：
[u-boot@MINI2440]# nfs 30008000 192.168.1.100:/home/tekkaman/development/share/zImage.img
dm9000 i/o: 0x20000300, id: 0x90000a46
DM9000: running in 16 bit mode
MAC: 08:08:11:18:12:27
operating at 100M full duplex mode
Using dm9000 device
File transfer via NFS from server 192.168.1.100; our IP address is 192.168.1.101
Filename '/home/tekkaman/development/share/zImage.img'.
Load address: 0x30008000
Loading: #################################################################
#######################################################
done
Bytes transferred = 2277540 (22c0a4 hex)
[u-boot@MINI2440]# nand erase 0x80000 0x300000
NAND erase: device 0 offset 0x80000, size 0x300000
Erasing at 0x36000001800000 --
0% complete.
OK
[u-boot@MINI2440]#
nand write 30008000 0x80000 300000
NAND write: device 0 offset 0x80000, size 0x300000
Writing at 0x36000000020000 -- 100% is complete. 3145728 bytes written: OK
内核引导:
[u-boot@MINI2440]# nand read 30008000 0x80000 300000
NAND read: device 0 offset 0x80000, size 0x300000
3145728 bytes read: OK
[u-boot@MINI2440]# bootm 30008000
## Booting kernel from Legacy Image at 30008000 ...
Image Name:
tekkaman
Created:
2010-03-29
12:59:51 UTC
Image Type:
ARM Linux Kernel Image (uncompressed)
Data Size:
2277476 Bytes =
2.2 MB
Load Address: 30008000
Entry Point:
30008040
Verifying Checksum ... OK
XIP Kernel Image ... OK
OK
Starting kernel ...
Uncompressing Linux... done, booting the kernel.
Linux version 2.6.33.1 (tekkaman@MAGI-Linux) (gcc version 4.3.2 (crosstool-NG-1.6.1-tekkaman) ) #5 Mon Mar 29 20:58:50 CST 2010
CPU: ARM920T [41129200] revision 0 (ARMv4T), cr=c0007177
CPU: VIVT data cache, VIVT instruction cache
Machine: MINI2440