mini2440_NFS starts with uboot

This article records how the mini2440 development board uses uboot to start the kernel through the nfs service.

background:

I have to use this board again today after putting it aside for a long time. I changed the machine before. Although kernel and rootfs are mounted via nfs, I can't get into u-boot... I got u-boot working, but nfs doesn't work again.

environment:

1.OS：ubuntu11.10；

2. Serial port tool: C-kermit

Involving:

1.Configuration of exports in nfs;

2. Setting of env in u-boot;

3. Problems encountered...

1. Configuration file in nfs: /etc/exports

$sudo vim /etc/exports

1. Add the nfs directory to be mounted on the development board:

/your/nfsroot/path 192.168.2.0/24(rw, sync, no_root_squash)

Mine is: /home/wang2/codePrj/ldd/rootfs/qtopia4 192.168.2.0/24 (rw, sync, no_root_squash)

2. Add the kernel file directory required by the development board:

/your/kernel/uImage/path 192.168.2.0/24(rw, sync,no_root_squash)

Mine is: /home/wang2/codePrj/ldd/imgs 192.168.2.0/24 (rw, sync, no_root_squash)

3.$sudo nfs-kernel-server  restart

2. About uImage in the first step:

Because u-boot needs to read the first 64 bytes of img information when booting kernel img, you must also create uImage (uboot Image) if you want to use u-boot to boot the kernel

1. Use make menuconfig to get zImage;

2. Use mkimage in u-boot tools to process zImage:

mkimage -A arm -O linux  -T kernel -C none -a 0x30008000 -e 0x30008000 -n kernel-2.6.32.2 -d zImage uImage

3. Parameter description:

     -A arm -------- Architecture architecture is arm

     -O linux -------- OS The operating system is Linux

     -T kernel -------- Type The image type is kernel

     -C none -------- Compressed The compression type is no compression

     -a 30008000 ---- image loading address (hex)

     -e 30008000 ---- entry kernel entry address (hex)

     -n kernel-2.6.32.2 --- name image name

     -d zImage ---- the original image file name uImage ---- the image file used by u-boot

3. Mount via nfs:

1. Tips:

Loading: *_*** ERROR: Cannot mount

reason:

a. After modifying /etc/exports, the nfs service was not restarted;

b. The firewall is not closed:

                           $sudo ufw status If it is active, you can pass

                           $sudo ufw disable Disable Ubuntu Fire Wall firewall

2. Tips:    

NAND read: device 0 offset 524288, size 2097152 ...

 2097152 bytes read: OK

## Booting image at 30008000 ...

   Image Name:   kernel-2.6.32.2

   Created:      2010-04-25   9:59:17 UTC

   Image Type:   ARM Linux Kernel Image (uncompressed)

   Data Size:    1966552 Bytes =  1.9 MB

   Load Address: 30008000

   Entry Point:  30008000

   Verifying Checksum ... OK

   XIP Kernel Image...OK

Starting kernel ...

data abort

pc : [<30008010>]    lr : [<33f94754>]

sp : 33f4faa0  ip : 30008000  fp : 00000002

r10: 00000000 r9: 33e7fe2c r8: 33f4ffdc

r7: 33f9e278 r6: 33f9e278 r5: 30008000 r4: 00000000

r3 : 30008000  r2 : 30000100  r1 : 000000c1  r0 : 33f4fce8

Flags: nZCv  IRQs off  FIQs off  Mode SVC_32

Resetting CPU ...

reason:

        a. The kernel type is incorrect and the mach-type is inconsistent;

        b. The entry address in uImage is incorrect, because mkimage will add 64 bytes (0x40) of additional information after processing, so change the -e option above to

0x30008040         

3. Tips:

                Load address: 0x30008000

                Loading: T T T T T T T .....

reason:

                The error at this moment was caused by the network cable being too long!!! I used a 3 to 5 meter network cable and it was only TTT; when I changed it to a 1 meter cable, it was ########! It was so weird                       

    4. extra:

            Before, I directly generated uImag according to the above command, and it could run after downloading it to the development board; but this time it always goes to download->cpu resetting->download->cpu resetting...; (the only difference between before and after is the use of the mkimage tool!) It was fixed through b.

4. Configuration of u-boot environment variables:

    1. Print the current env:

        #printenv

    2. Set env:

        #setenv env_name env_value

        #setenv bootargs 'noinitrd root=/dev/nfs rw nfsroot=192.168.2.3:/home/wang2/codePrj/ldd/rootfs/qtopia4 ip=192.168.2.4:192.168.2.3:255.255.255.0 console=ttySAC0,115200  mem=64M'

My env:        

[zhong@mini2440]# printenv 

bootdelay=1

baudrate=115200

ethaddr=08:08:11:18:12:27

zhong=bmp d 70000

 stdin=serial

stdout=serial

stderr=serial

ethact=dm9000

filesize=266854

fileaddr=30008000

gatewayip=192.168.2.1

netmask=255.255.255.0

ipaddr=192.168.2.4

serverip=192.168.2.3

bootcmd=nfs 0x30008000 192.168.2.3:/home/wang2/codePrj/ldd/imgs/uImage;bootm

 0x30008000

bootargs=noinitrd root=/dev/nfs rw nfsroot=192.168.2.3:/home/wang2/codePrj/ldd/rootfs/qtopia4 ip=192.168.2.4:192.168.2.3:255.255.255.0 console=ttySAC0,115200  mem=64M

5. NFS can be started

Try to bring eth0 interface up......NFS root ...Done

Please press Enter to activate this console.