U-BOOT下使用bootm引导内核方法

注：

  u-boot 使用的是打上：

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上keety大侠提供的补丁生成的u-boot-1.1.3

这段时间不断有人问我u-boot启动内核的问题，记得在上次提供的u-boot源码中提到了go的方案，不过其实u-boot本来有一种更好的方案： bootm

花了不少时间，查看了论坛上不少的帖子，认真阅读了bootm的源码，终于使用bootm把内核给跑起来了， 现把解决方法介绍如下：

一、在开始之前先说明一下bootm相关的东西。

1、首先说明一下，S3C2410架构下的bootm只对sdram中的内核镜像文件进行操作(好像AT91架构提供了一段从flash复制内核镜像的代码，不过针对s3c2410架构就没有这段代码，虽然可以在u-boot下添加这段代码，不过好像这个用处不大)，所以请确保你的内核镜像下载到sdram中，或者在bootcmd下把flash中的内核镜像复制到sdram中。

2、-a参数后是内核的运行地址，-e参数后是入口地址。

3、

1）如果我们没用mkimage对内核进行处理的话，那直接把内核下载到0x30008000再运行就行，内核会自解压运行（不过内核运行需要一个tag来传递参数，而这个tag建议是由bootloader提供的，在u-boot下默认是由bootm命令建立的）。

2）如果使用mkimage生成内核镜像文件的话，会在内核的前头加上了64byte的信息，供建立tag之用。bootm命令会首先判断bootm xxxx 这个指定的地址xxxx是否与-a指定的加载地址相同。

(1)如果不同的话会从这个地址开始提取出这个64byte的头部，对其进行分析，然后把去掉头部的内核复制到-a指定的load地址中去运行之

(2)如果相同的话那就让其原封不同的放在那，但-e指定的入口地址会推后64byte，以跳过这64byte的头部。

二、好，接着介绍使用mkimage生成镜像文件并下载运行的方法。

方法一、

1、首先，用u-boot/tools/mkimage这个工具为你的内核加上u-boot引导所需要的文件头，具体做法如下：

[root@localhost tftpboot]#mkimage -n 'linux-2.6.14' -A arm -O linux -T kernel -C none -a 0x30008000 -e 0x30008000 -d zImage zImage.img

Image Name:   linux-2.6.14

Created:      Fri Jan 12 17:14:50 2007

Image Type:   ARM Linux Kernel Image (uncompressed)

Data Size:    1262504 Bytes = 1232.91 kB = 1.20 MB

Load Address: 0x30008000

Entry Point:  0x30008000

这里解释一下参数的意义：

        -A ==&gt; set architecture to 'arch'

        -O ==&gt; set operating system to 'os'

        -T ==&gt; set image type to 'type'

        -C ==&gt; set compression type 'comp'

        -a ==&gt; set load address to 'addr' (hex)

        -e ==&gt; set entry point to 'ep' (hex)

        -n ==&gt; set image name to 'name'

        -d ==&gt; use image data from 'datafile'

        -x ==&gt; set XIP (execute in place)

2 、下载内核

U-Boot 1.1.3 (Jan 12 2007 - 16:16:36)

U-Boot code: 33F80000 -&gt; 33F9BAC0  BSS: -&gt; 33F9FBAC

RAM Configuration:

Bank #0: 30000000 64 MB

Nor Flash: 512 kB

Nand Flash:  64 MB

In:    serial

Out:   serial

Err:   serial

Hit any key to stop autoboot:  0

sbc2410=&gt;tftp 0x31000000 zImage.img        

TFTP from server 192.168.1.115; our IP address is 192.168.1.128

Filename 'zImage.img'.

Load address: 0x31000000

Loading: #################################################################

        #################################################################

        ####################################################

done

Bytes transferred = 1263324 (1346dc hex)

3.运行 

sbc2410=&gt;bootm 0x31000000

## Booting image at 31000000 ...

  Image Name:   linun-2.6.14 

  Image Type:   ARM Linux Kernel Image (uncompressed)

  Data Size:    1263260 Bytes =  1.2 MB

  Load Address: 30008000

  Entry Point:  30008000

  Verifying Checksum ... OK

OK

Starting kernel ...

Uncompressing Linux.............................................................Linux version 2.6.14 (root@luofuchong) (gcc version 3.4.1) #21 Fri Oct 20 17:206CPU: ARM920Tid(wb) [41129200] revision 0 (ARMv4T)

Machine: SMDK2410

Memory policy: ECC disabled, Data cache writeback

CPU S3C2410A (id 0x32410002)

S3C2410: core 202.800 MHz, memory 101.400 MHz, peripheral 50.700 MHz

S3C2410 Clocks, (c) 2004 Simtec Electronics

CLOCK: Slow mode (1.500 MHz), fast, MPLL on, UPLL on

USB Control, (c) 2006 sbc2410

CPU0: D VIVT write-back cache

CPU0: I cache: 16384 bytes, associativity 64, 32 byte lines, 8 sets

CPU0: D cache: 16384 bytes, associativity 64, 32 byte lines, 8 sets

Built 1 zonelists

Kernel command line: console=ttySAC0 root=/dev/nfs nfsroot=192.168.1.115:/frien"irq: clearing subpending status 00000002

PID hash table entries: 512 (order: 9, 8192 bytes)

timer tcon=00500000, tcnt a509, tcfg 00000200,00000000, usec 00001e4c

Console: colour dummy device 80x30

Dentry cache hash table entries: 16384 (order: 4, 65536 bytes)

Inode-cache hash table entries: 8192 (order: 3, 32768 bytes)

Memory: 64MB = 64MB total

Memory: 62208KB available (1924K code, 529K data, 108K init)

Mount-cache hash table entries: 512

CPU: Testing write buffer coherency: ok

softlockup thread 0 started up.

NET: Registered protocol family 16

S3C2410: Initialising architecture

SCSI subsystem initialized

usbcore: registered new driver usbfs

usbcore: registered new driver hub

S3C2410 DMA Driver, (c) 2003-2004 Simtec Electronics

DMA channel 0 at c4800000, irq 33

DMA channel 1 at c4800040, irq 34

DMA channel 2 at c4800080, irq 35

DMA channel 3 at c48000c0, irq 36

NetWinder Floating Point Emulator V0.97 (double precision)

devfs: 2004-01-31 Richard Gooch ([email protected])

devfs: devfs_debug: 0x0

devfs: boot_options: 0x1

yaffs Oct 18 2006 12:39:51 Installing.

Console: switching to colour frame buffer device 30x40

fb0: s3c2410fb frame buffer device

fb1: Virtual frame buffer device, using 1024K of video memory

led driver initialized

s3c2410 buttons successfully loaded

s3c2410_serial0 at MMIO 0x50000000 (irq = 70) is a S3C2410

s3c2410_serial1 at MMIO 0x50004000 (irq = 73) is a S3C2410

s3c2410_serial2 at MMIO 0x50008000 (irq = 76) is a S3C2410

io scheduler noop registered

io scheduler anticipatory registered

io scheduler deadline registered

io scheduler cfq registered

RAMDISK driver initialized: 16 RAM disks of 4096K size 1024 blocksize

usbcore: registered new driver ub

Cirrus Logic CS8900A driver for Linux (Modified for SMDK2410)

eth0: CS8900A rev E at 0xe0000300 irq=53, no eeprom , addr: 08: 0:3E:26:0A:5B

S3C24XX NAND Driver, (c) 2004 Simtec Electronics

s3c2410-nand: mapped registers at c4980000

s3c2410-nand: timing: Tacls 10ns, Twrph0 30ns, Twrph1 10ns

NAND device: Manufacturer ID: 0xec, Chip ID: 0x76 (Samsung NAND 64MiB 3,3V 8-bi)Scanning device for bad blocks

Bad eraseblock 1884 at 0x01d70000

Creating 4 MTD partitions on "NAND 64MiB 3,3V 8-bit":

0x00000000-0x00020000 : "vivi"

0x00020000-0x00030000 : "param"

0x00030000-0x00200000 : "kernel"

0x00200000-0x04000000 : "root"

usbmon: debugfs is not available

s3c2410-ohci s3c2410-ohci: S3C24XX OHCI

s3c2410-ohci s3c2410-ohci: new USB bus registered, assigned bus number 1

s3c2410-ohci s3c2410-ohci: irq 42, io mem 0x49000000

hub 1-0:1.0: USB hub found

hub 1-0:1.0: 2 ports detected

Initializing USB Mass Storage driver...

usbcore: registered new driver usb-storage

USB Mass Storage support registered.

usbcore: registered new driver usbmouse

drivers/usb/input/usbmouse.c: v1.6:USB HID Boot Protocol mouse driver

mice: PS/2 mouse device common for all mice

s3c2410 TouchScreen successfully loaded

UDA1341 audio driver initialized

NET: Registered protocol family 2

IP route cache hash table entries: 1024 (order: 0, 4096 bytes)

TCP established hash table entries: 4096 (order: 2, 16384 bytes)

TCP bind hash table entries: 4096 (order: 2, 16384 bytes)

TCP: Hash tables configured (established 4096 bind 4096)

TCP reno registered

TCP bic registered

NET: Registered protocol family 1

IP-Config: Complete:

     device=eth0, addr=192.168.1.128, mask=255.255.255.0, gw=192.168.1.1,

    host=luofuchong, domain=, nis-domain=(none),

    bootserver=192.168.1.1, rootserver=192.168.1.115, rootpath=

Looking up port of RPC 100003/2 on 192.168.1.115

Looking up port of RPC 100005/1 on 192.168.1.115

VFS: Mounted root (nfs filesystem).

Mounted devfs on /dev

Freeing init memory: 108K

init started:  BusyBox v1.1.3 (2006.09.20-14:52+0000) multi-call binary

Starting pid 696, console /dev/tts/0: '/etc/init.d/rcS'

Please press Enter to activate this console.

方法二、

[root@localhost tftpboot]#mkimage -n 'linux-2.6.14' -A arm -O linux -T kernel -C none -a 0x30008000 -e 0x30008040 -d zImage zImage.img

Entry Point:  0x30008040

sbc2410=&gt;tftp 0x30008000 zImage.img        

Load address: 0x30008000

sbc2410=&gt;bootm 0x30008000

## Booting image at 30008000 ...

   Image Name:   linux-2.6.14

   Image Type:   ARM Linux Kernel Image (uncompressed)

   Data Size:    1261056 Bytes =  1.2 MB

   Load Address: 30008000

   Entry Point:  30008040

   Verifying Checksum ... OK

   XIP Kernel Image ... OK

内核启动信息省。。。。

三、固化

如果你想把镜像文件写入flash，每次开机后让u-boot帮你复制到sdram中，再使用bootm命令引导的话，可以按照这样操作：

sbc2410=&gt;tftp 0x30008000 zImage.img

sbc2410=&gt;nand erase 0x30000 0x1d0000

NAND erase: device 0 offset 196608, size 1900544 ... OK

sbc2410=&gt;nand write 0x30008000 0x30000 0x1d0000

NAND write: device 0 offset 196608, size 1900544 ...  1900544 bytes written: OK

设置u-boot启动命令：

1、针对方法一：

sbc2410=&gt;setenv bootcmd nand read 0x31000000 0x30000 0x1d0000\;bootm 0x31000000

sbc2410=&gt;saveenv

Saving Environment to NAND...

Erasing Nand...Writing to Nand... done

2、针对方法二：

sbc2410=&gt;setenv bootcmd nand read 0x30008000 0x30000 0x1d0000\;bootm 0x30008000

sbc2410=&gt;reset

启动信息略。。。。

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