下載與燒寫
（1）通過網絡、串口、U盤、SD卡等方式將文件傳輸到SDRAM；
（2）使用Nand Flash或Nor Flash相關的讀寫命令將SDRAM中的數據燒入Flash。
如果使用 SD卡和U盤形式更新U-boot，那麼首先SD卡和U盤中必須有FAT32文件系統，並在裏面存放了u-boot.bin 文件。
1) 通過SD卡燒入Nand Flash：
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[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 "Product 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 |
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[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) 通過TFTP服務燒入Nand Flash：
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[u-boot@MINI2440]# tftpboot 30008000 192.168.1.100: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 TFTP from server 192.168.1.100; our IP address is 192.168.1.101 Filename 'u-boot.bin'. 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) 通過NFS 服務燒入Nand Flash：
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[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 |
內核引導
（1）用U-boot的mkimage工具處理內核映像zImage。
（2）通過網絡、串口、U盤、SD卡等方式將處理過的內核映像傳輸到SDRAM的一定位置（一般使用0x30008000）
（3）然後使用”bootm"等內核引導命令來啓動內核。
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爲什麼要用U-boot的mkimage工具處理內核映像zImage？ 因爲在用bootm命令引導內核的時候，bootm需要讀取一個64字節的文件頭，來獲取這個內核映象所針對的CPU體系結構、OS、加載到內存中的位置、在內存中入口點的位置以及映象名等等信息。這樣bootm才能爲OS設置好啓動環境，並跳入內核映象的入口點。而mkimage就是添加這個文件頭的專用工具。具體的實現請看U-boot中bootm的源碼和mkimage的源碼。 |
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mkimage工具的使用：
參數說明： -A 指定CPU的體系結構，可用值有：alpha、arm 、x86、ia64、mips、mips64、ppc 、s390、sh、sparc 、sparc64、m68k等 -O 指定操作系統類型，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 指定映象類型，可用值有：standalone、kernel、ramdisk、multi、firmware、script、filesystem -C 指定映象壓縮方式，可用值有： none 不壓縮(一般使用這個，因爲zImage是已經被bzip2壓縮過的自解壓內核) gzip 用gzip的壓縮方式 bzip2 用bzip2的壓縮方式 -a 指定映象在內存中的加載地址，映象下載到內存中時，要按照用mkimage製作映象時，這個參數所指定的地址值來下載 -e 指定映象運行的入口點地址，這個地址就是-a參數指定的值加上0x40（因爲前面有個mkimage添加的0x40個字節的頭） -n 指定映象名 -d 指定製作映象的源文件
以下是製作內核映像的命令示例： mkimage -n 'tekkaman' -A arm -O linux -T kernel -C none -a 0x30008000 -e 0x30008040 -d zImage zImage.img |
1) 通過SD卡引導內核：
首先SD卡中必須有FAT32文件系統，並在裏面存放了處理過的內核映像文件。
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[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 "Product 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) 通過TFTP服務引導內核:
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[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 |