Re: kernel panic after VFS mount in FPGA board

[pcuser p <pcuser.mails@xxxxxxxxx>]

I am trying to create a root file systems using busybox for ARM926EJ-s based board.
I'm using linaro tool chain 4.6.1(arm-linux-gnueabi-) in ubuntu 10.04

First step,I started with 
make defconfig
CFLAGS=-march=armv5te make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- menuconfig
enabled only static binary option 
CFLAGS=-march=armv5te make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- CONFIG_PREFIX=$ROOTFS install


when I do readelf on the busybox binary,I'm getting below messages
File Attributes
  Tag_CPU_name: "7-A"
  Tag_CPU_arch: v7
  Tag_CPU_arch_profile: Application
  Tag_ARM_ISA_use: Yes
  Tag_THUMB_ISA_use: Thumb-2
  Tag_FP_arch: VFPv3-D16
  Tag_ABI_PCS_wchar_t: 4
  Tag_ABI_FP_denormal: Needed
  Tag_ABI_FP_exceptions: Needed
  Tag_ABI_FP_number_model: IEEE 754
  Tag_ABI_align_needed: 8-byte
  Tag_ABI_align_preserved: 8-byte, except leaf SP
  Tag_ABI_enum_size: int
  Tag_ABI_HardFP_use: SP and DP
  Tag_DIV_use: Not allowed

If i use this binary in for root file system,with init=/linuxrc
I'm getting undefined instruction error and kernel panics
init (1): undefined instruction: pc=40047930
Code: 0000aa80 00000714 e3e00000 e1a0f00e (eca0420c)
Kernel panic - not syncing: Attempted to kill init!


I see that the busybox is compiled for different arm architecture, other than the one i specified (armv5te)

To identify the issue is with busybox or toolchain or configuration,I tried with hello program (hello world) as init (init =/sbin/hello).
arm-linux-gnueabi-gcc -march=armv5te -o hello hello.c
Failed to execute /sbin/hello.  Attempting defaults...
init (1): undefined instruction: pc=0006f7b2
Code: 2001 2000 f85d fb08 (bf00) f84d



I'm trying to get past the root file system for last few days,for this problem i can't clearly get any idea about what the cause is.
kindly help me in clearing this problem

On Wed, Apr 11, 2012 at 7:34 PM, Kristof Provost <kristof@xxxxxxxxxx> wrote:

On 2012-04-11 19:03:42 (+0530), pcuser p <pcuser.mails@xxxxxxxxx> wrote:
> I'm getting kernel panic after cramfs root file system is mounted,I am
> expecting to enter login prompt after root file system is mounted.
>

> Kernel cmd line : mem=32M console=ttySAC0,115200 root=/dev/ram0
> rootfstype=cramfs init=/linuxrc initrd=0x80800000,8M user_debug=31
>

> *linuxrc init script*
> #!/bin/sh**

> /bin/echo "mount /etc as ramfs"
> /bin/mount -n -t ramfs ramfs /etc
> /bin/mount -n -t tmpfs tmpfs /tmp
> exec /sbin/init
>
> I tried  with this init script,but kernel is hanging without any message..
> I changed it a bit as below, to see if it reads the init script
>
> #!/bin/sh
> /bin/echo "Entering Init script"
>

Init isn't allowed to exit.
That's probably why you're seeing the panic. Try starting a shell after
the /bin/echo, or just using /bin/sh as init.

> with this changes,I am expect to get print message "Entering Init script"
> after cramfs is mounted,but I am getting panic message which is attached
> below.
>

Probably because the system panics before the stdout buffers make it to
the console.

Regards,
Kristof

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