AM37x EVM Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(179,2)

Dave:

So you have one partition on the SD Card.   This should have X-Loader (MLO file) and U-Boot. 

Do you want the kernel to also be on the SD Card in the same partition or nfs mounted?

Do you want the file system to be nfs mounted also?

Regards,

Michael T

Michael,

I am setting up an SD card for development to test driver configuration changes to the kernel.

I'm new to this development environment.

Which configuration would you recommend: same partition or NFS?

These files are on the SD and I can boot to the U-Boot prompt.

MLO

boot.cmd

boot.scr

u-boot.bin

uImage

Dave:

This wiki article is part of the AM37x SDK 4.0 SW Developer's Guide and covers modification to

U-Boot parameters:

http://processors.wiki.ti.com/index.php/Modifying_U-boot

To make your changes you would connect a serial terminal and power-on the EVM

and press a key to stop boot process.  Type printenv to see current environment.

A summary of the commands to enter at the U-Boot prompt would be:

setenv serverip xxx.xxx.xxx.xxx
setenv ipaddr yyy.yyy.yyy.yyy
setenv loadaddr 0x82000000
setenv bootfile uImage
setenv tftpuimage tftp ${loadaddr} ${bootfile}
setenv nfsargs 'mem=128M console=ttyS0,115200n8 noinitrd rw ip=dhcp root=/dev/nfs nfsroot=xxx.xxx.xxx.xxx:/home/user/ti-sdk-AM3715-evm-4.0.0.0/filesystem'
setenv tftp_nfs_boot run tftpuimage; setenv bootargs ${nfsargs}; bootm ${loadaddr}
setenv bootcmd run tftp_nfs_boot
saveenv

1. xxx.xxx.xxx.xxx is the Linux host IP address.  Type ifconfig in Linux host terminal.

2. yyy.yyy.yyy.yyy is target board IP address.  Best to connect PC and EVM to a router and use dhcp U-Boot cmd to determine this.

3. See instruction about modifying /etc/default/xinetd file here (in section titled Setup a TFTP Server for Kernel Downloads)

http://processors.wiki.ti.com/index.php/AM37x_EVM_Software_Developer%27s_Guide

(These instructions are specific to Ubuntu 10.04 Linux host)

4. AM37x SDK installer configures the directory '/home/<user_id>/ti-sdk-AM3715-evm-4.0.0.0/filesystem' to map to the root directory

    of the target EVM.

5. After kernel build, copy the kernel to '/home/<user_id>/ti-sdk-AM3715-evm-4.0.0.0/filesystem\boot'

Regards,

Michael T

PS: Please mark this post as answered via the Verify Answer button below if you think it answers your question.  Thanks!

Dave:

One additional tip.  If using minicom, do Ctrl-A W to turn on word wrap before entering the long u-boot commands.

setenv nfsargs... command needs to beon one line.

regards,

Michael T

Dave:

One correction...the location to copy the rebuilt Linux kernal is:

/tftpboot/uImage

on the Linux host machine.

If you still have a problem please send you updated printenv output.

Regards,

Michael T

Michael,

An error is displayed setting tftp_nfs_boot

OMAP3_EVM # setenv tftp_nfs_boot run tftpuimage; setenv bootargs ${nfsargs}; bootm ${loadaddr}
Wrong Image Format for bootm command
ERROR: can't get kernel image!
OMAP3_EVM #

Printenv attached

Michael,

The SD card boots to the  U-boot prompt

How do I get to the linux login prompt? Normally I type boot at the U-boot prompt.

It may be easier to put the filesystem on the SD card.

What variables need to be set to accomplish this?

Dave:

If you don't stop the boot process it should boot up all the way to the Linux login prompt.  Where does it stop?

If you are going to be making kernel changes, it is easiset to have the file system on the Linux host over the

network.  Could you send the terminal output during boot up?

Are you using the AM37x SDk 4.0 installation? 

regards,

Michael T

Michael,

There was a typo in the bootargs variable

The board now boots.