2008-10-16 10:45:05     Null Pointer debugging in Kernel

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2008-10-16 10:45:05     Null Pointer debugging in Kernel

Appalayagari Sreedhar (INDIA)

Message: 63791   

 

Hi,

 

I am working with custom board Bf533 , 2007 R1 distribution, u-boot 2007 R1 version.

 

I have turned off the printk function in the kernel to increase the booting speed. very often i am facing the booting problem. this i am able to reproduce 3/10 times.

 

When i turned on printk function in kernel the problem seems to happen very rarely once in 3 hours.  I captured the log when this problem occured, I saw that there is a Null Pointer access. I am pasting the kernel log at the end of the mail.

 

Can you provide some clue why this Null Pointer access occuring in the kernel while booting.

 

How to debug the Null Pointer access issues in the kernel.

 

Kernel log

 

bfin-uart.1: ttyBF0 at MMIO 0xffc00400 (irq = 21) is a BFIN-UART

RAMDISK driver initialized: 1 RAM disks of 4096K size 1024 blocksize

Network interface: "eth0"<6>/proc/HW_ADDR created

ret value from smsc911x_drv_probe Func is 0

uclinux[mtd]: RAM probe address=0x2f00000 size=0x1000000

Creating 1 MTD partitions on "RAM":

0x00000000-0x01000000 : "ROMfs"

 

 

NULL pointer access (probably)

 

CURRENT PROCESS:

 

COMM=khelper PID=45

return address: 0x001881ce; contents of [PC-16...PC+8]:

e800 0000 1805 e801 0000 e2ff ffbe 6350

e801 0000 0010 3208 0578 e800 0000 6003 X

e408 0042 5010 e608 0042 3046 4d68 4f68

 

RETE:  00000000  RETN: 0048e008  RETX: 001881ce  RETS: 00192150

IPEND: 8070  SYSCFG: 6d696c5e

SEQSTAT: 00060027    SP: 0048df2c

R0: ffffffff    R1: 00010000    R2: 00000001    R3: 00000000

R4: 5a5f5f00    R5: 00000006    R6: 00000000    R7: ffffffff

P0: 002ebd00    P1: ffffffff    P2: 0048e000    P3: 6972656d

P4: 00000006    P5: 002ebcf0    FP: 0048e008

A0.w: 00000000    A0.x: 00000000    A1.w: 00000000    A1.x: 00000000

LB0: 00000000  LT0: 00000000  LC0: 00000000

LB1: 00000000  LT1: 00000000  LC1: 00000000

B0: 00000000  L0: 00000000  M0: 00000000  I0: 00000001

B1: 00000000  L1: 00000000  M1: 00000000  I1: 00000000

B2: 00000000  L2: 00000000  M2: 00000000  I2: 00000000

B3: 00000000  L3: 00000000  M3: 00000000  I3: 00000000

 

USP: 00000000   ASTAT: 00003024

DCPLB_FAULT_ADDR=00000104

ICPLB_FAULT_ADDR=001881ce

 

 

Hardware Trace:

0 Target : <0x0018368d> { _trap_c + 0x1 }

   Source : <0xffa00b78> { _exception_to_level5 + 0xb4 }

1 Target : <0xffa00ac4> { _exception_to_level5 + 0x0 }

   Source : <0xffa00ac3> { _ex_trap_c + 0x5b }

2 Target : <0xffa00bf0> { _trap + 0x0 }

   Source : <0xffa00170> { _ret_from_fork + 0xc8 }

3 Target : <0xffa00170> { _ret_from_fork + 0xc8 }

   Source : <0xffa00a00> { _return_from_exception + 0x12 }

4 Target : <0x0018368c> { _trap_c + 0x0 }

   Source : <0xffa00b78> { _exception_to_level5 + 0xb4 }

5 Target : <0xffa00ac4> { _exception_to_level5 + 0x0 }

   Source : <0xffa00ac2> { _ex_trap_c + 0x5a }

6 Target : <0xffa00bf0> { _trap + 0x0 }

   Source : <0xffa0016e> { _ret_from_fork + 0xc6 }

7 Target : <0xffa0016e> { _ret_from_fork + 0xc6 }

   Source : <0xffa00a00> { _return_from_exception + 0x12 }

8 Target : <0x0018368c> { _trap_c + 0x0 }

   Source : <0xffa00b78> { _exception_to_level5 + 0xb4 }

9 Target : <0xffa00ac4> { _exception_to_level5 + 0x0 }

   Source : <0xffa00ac2> { _ex_trap_c + 0x5a }

10 Target : <0xffa00bf0> { _trap + 0x0 }

   Source : <0xffa0016c> { _ret_from_fork + 0xc4 }

11 Target : <0xffa0016c> { _ret_from_fork + 0xc4 }

   Source : <0xffa00a00> { _return_from_exception + 0x12 }

12 Target : <0x0018368c> { _trap_c + 0x0 }

   Source : <0xffa00b78> { _exception_to_level5 + 0xb4 }

13 Target : <0xffa00ac4> { _exception_to_level5 + 0x0 }

   Source : <0xffa00ac2> { _ex_trap_c + 0x5a }

14 Target : <0xffa00bf0> { _trap + 0x0 }

   Source : <0xffa0016a> { _ret_from_fork + 0xc2 }

15 Target : <0xffa0016a> { _ret_from_fork + 0xc2 }

   Source : <0xffa00a00> { _return_from_exception + 0x12 }

Stack from 0048df0c:

        00000000 ffa00b7c 002b46fc 002b46fc 002b46f8 00000000 00000000 00000000

        001881ce 00008070 00060027 00000000 0048e008 001881ce 001881ce 00192150

        ffffffff 00003024 00000000 00000000 00000000 00000000 00000000 00000000

        00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000

        00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000

        00000000 00000000 00000000 00000001 00000000 0048e008 002ebcf0 00000006

Call Trace:

 

Kernel panic - not syncing: Kernel exception

 

Best Regards, Sreedhar

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2008-10-16 11:12:04     Re: Null Pointer debugging in Kernel

Andrea Federico Grisotto (ITALY)

Message: 63792   

 

Hi Sreedhar,

 

Your problem is similar to an old bug present in 2007R1 release, for more info

 

look this thread:

 

http://blackfin.uclinux.org/gf/project/uclinux-dist/forum/?action=ForumBrowse&_forum_action=MessageReply&message_id=59841

 

ciao Andrea.

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2008-10-16 14:13:59     Re: Null Pointer debugging in Kernel

Robin Getz (UNITED STATES)

Message: 63802   

 

Sreedhar:

 

There are many, many bug fixes which could be cuasing this (most likely the one that Andrea points to) - that you refuse to use since you don't want to update to the 2007R1 svn branch. (As Andrea points out - it was commited to the branch - over a year ago Oct 24, 2007).

 

Update - it is not just for fun that I continue to say this.

 

-Robin

 

 

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2008-10-16 14:49:00     Re: Null Pointer debugging in Kernel

Appalayagari Sreedhar (INDIA)

Message: 63805   

 

Hi Robin,

 

I am willing to update the svn branches of 2007 R1, I could not do it because i was facing some problems with svn usage here. Soon I will be updating.

 

I thought initially the exception is the problem, but after your email to the thread Kernel booting Problem(this thread also started by me), i concluded it is the Null Pointer access problem. So i posted again separately with diffrent thread.

 

sorry robin, if this has irritated you.

 

updating is delayed, because i am new to all this.

 

I will update soon and let you know the results soon.

 

Thankyou very much for the support.

 

Best Regards, Sreedhar.

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2008-10-16 14:51:01     Re: Null Pointer debugging in Kernel

Appalayagari Sreedhar (INDIA)

Message: 63806   

 

Hi,

 

Thankyou Andrea.

 

I will check it.

 

Best Regards,Sreedhar.

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