本文经过我参照网上好心人的做法整理而成，如有侵犯您的权益，请留言，我改正。
首先，确定u-boot中的MACH_TYPE。在u-boot的include/asm-arm/mach-types.h文件中针对不同的CPU定义了非常多的MACH_TYPE,可以找到下面这个定义：
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#define MACH_TYPE_SMDK2440 1008 //针对2440的MACH_TYPE码的值定义为1008
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那么我们就修改u-boot的MACH_TYPE代码引用部分，确定u-boot的MACH_TYPE。如下：
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#gedit board/samsung/my2440/my2440.c //修改board_init函数
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/* arch number of SMDK2410-Board */
//gd->bd->bi_arch_number = MACH_TYPE_SMDK2410;
改为：
gd->bd->bi_arch_number = MACH_TYPE_SMDK2440;
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其次，确定kernel中的MACH_TYPE。在kernel的arch/arm/tools/mach-types文件中也针对不同的CPU定义了非常多的MACH_TYPE,也可以找到下面这个定义：
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smdk2440 MACH_SMDK2440 SMDK2440 1008
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那么我们就修改kernel的MACH_TYPE代码引用部分，确定kernel的MACH_TYPE。如下：
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#gedit arch/arm/mach-s3c2440/mach-smdk2440.c //修改文件最后面
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//MACHINE_START(S3C2440, "SMDK2440")
改为：
MACHINE_START(SMDK2440, "SMDK2440")
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#gedit arch/arm/kernel/head.S //在ENTRY(stext)下添加如下代码(红色部分)
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ENTRY(stext)
mov r0, #0
mov r1, #0x3f0 //上面的MACH_TYPE值1008换成十六进制就是0x3f0
ldr r2, =0x30000100
msr cpsr_c, #PSR_F_BIT | PSR_I_BIT | SVC_MODE
.......
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分别重新编译u-boot和kernel。u-boot下载后，记得要saveenv；kernel用tftp下载到内存后使用go命令来测试引导内核，结果可以引导了，如下：
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## Starting application at 0x30008000 ... Uncompressing Linux............................................................. Linux version 2.6.25.8 (root@localhost.localdomain) (gcc version 4.3.3 (Sourcer0 CPU: ARM920T [41129200] revision 0 (ARMv4T), cr=00007177 Machine: SMDK2440 Warning: bad configuration page, trying to continue Memory policy: ECC disabled, Data cache writeback CPU S3C2440A (id 0x32440001) S3C244X: core 405.000 MHz, memory 101.250 MHz, peripheral 50.625 MHz S3C24XX Clocks, (c) 2004 Simtec Electronics CLOCK: Slow mode (1.500 MHz), fast, MPLL on, UPLL on |
在这次u-boot移植的过程中，我明白了zImage并不能直接由u-boot从nand中引导，而uImage是可以由u-boot直接引导的，下面说明引导过程，首先进入内核目录，保证编译通过，最好是以前用别人的u-boot能启动的内核，然后执行
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[root@localhost linux-2.6.25.8]# make uImage
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即可在内核的boot目录下生成uImage，拷贝到tftpboot目录待下载。
查看内核在arch/arm/plat-s3c24xx/common-smdk.c中的分区情况如下：
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[0] = {
.name = "EmbedSky_Board_uboot_T",
.size = 0x00000000,
.offset = 0x00040000,
},
[1] = {
.name = "EmbedSky_Board_kernel",
.offset = 0x00200000,
.size = 0x00200000,
},
[2] = {
.name = "EmbedSky_Board_yaffs2",
.offset = 0x00400000,
.size = 0x0FB80000,
}
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设置修改u-boot的启动参数，在u-boot命令行下输入：
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//设置启动参数，意思是将nand中0x50000-0x00200000(和kernel分区一致)的内容读到内存0x31000000中，然后用bootm命令来执行
set bootcmd 'nand read 0x31000000 0x200000 0x00200000;bootm 0x31000000'
saveenv
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把uImage.img用tftp下载到内存中，然后再固化到Nand Flash中，操作和执行图如下：
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tftp 0x30000000 uImage.img //将uImage.img下载到内存0x30000000处
nand erase 0x200000 0x200000 //擦除nand的0x50000-0x200000的内容
nand write 0x30000000 0x200000 0x200000 //将内存0x30000000处的内容写入到nand的0x50000处
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TFTP from server 192.168.0.102; our IP address is 192.168.0.101
Filename 'uImage'.
Load address: 0x30000000
Loading: *
ARP Retry count exceeded; starting again
dm9000 i/o: 0x20000300, id: 0x90000a46
DM9000: running in 16 bit mode
MAC: 08:00:3e:26:0a:5b
operating at unknown: 0 mode
Using dm9000 device
TFTP from server 192.168.0.102; our IP address is 192.168.0.101
Filename 'zImage'.
Load address: 0x30000000
Loading: *
ARP Retry count exceeded; starting again
dm9000 i/o: 0x20000300, id: 0x90000a46
DM9000: running in 16 bit mode
MAC: 08:00:3e:26:0a:5b
operating at unknown: 0 mode
Using dm9000 device
TFTP from server 192.168.0.102; our IP address is 192.168.0.101
Filename 'zImage'.
Load address: 0x30000000
Loading: #################################################################
#################################################################
##########
done
Bytes transferred = 2052152 (1f5038 hex)
YY2440 # nanad erase 0x200000 0x200000
Unknown command 'nanad' - try 'help'
YY2440 # nand erase 0x200000 0x200000
NAND erase: device 0 offset 0x200000, size 0x200000
Erasing at 0x2 -- 4063232% complete.
OK
YY2440 # nand write 0x30000000 0x200000 0x200000
NAND write: device 0 offset 0x200000, size 0x200000
2097152 bytes written: OK
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然后boot即可成功引导内核，重新上电也可以……
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YY2440 # boot
NAND read: device 0 offset 0x200000, size 0x200000
2097152 bytes read: OK
## Booting kernel from Legacy Image at 31000000 ...
Image Name: Linux-2.6.25.8
Created: 2010-01-20 16:12:01 UTC
Image Type: ARM Linux Kernel Image (uncompressed)
Data Size: 2052152 Bytes = 2 MB
Load Address: 30008000
Entry Point: 30008000
Verifying Checksum ... OK
Loading Kernel Image ... OK
OK
Starting kernel ...
Uncompressing Linux.............................................................
Linux version 2.6.25.8 (root@localhost.localdomain) (gcc version 4.3.3 (Sourcer0
CPU: ARM920T [41129200] revision 0 (ARMv4T), cr=00007177
Machine: SMDK2440
Warning: bad configuration page, trying to continue
Memory policy: ECC disabled, Data cache writeback
CPU S3C2440A (id 0x32440001)
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参考文献http://blog.chinaunix.net/u3/101649/showart_2126764.html
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