Bad Block Handling in jffs2

Bad Block Handling in jffs2

[Kschoo70C]

Hi,
   My nand device has a few bad blocks. Therefore if I copy the jffs2 formated 
   image to the device, some files are missing from the file systems.
 
   In http://www.linux-mtd.infradead.org/tech/nand.html, it is stated that 
   
   "if you have a bad block on your chip, just skip this block and copy 
   the data to the next block. JFFS2 is able to handle this gap.".

   So, I write a program to skip the bad block, and copy the data to the next block. 
   The missing file seems to appear on the file system now, the size looks correct. 
   But when I diff the binary of the file to that of original, they are different 
   and the binary failed to execute.

   I don't know much about jffs2 bad block handling, the only information I have is 
   as mentioned above. Am I missing any other information ?

   Is anyone manage to transfer an image to the nand device that has bad blocks 
   without losing any files ?

   Note that there is no problem to copy the same image to nand devices 
   which are bad blocks free 

   Thanks in advance.

regards
choo


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Re: Bad Block Handling in jffs2

[Thomas Gleixner]

On Thursday 30 January 2003 17:17, Kschoo70C@netscape.net wrote:
>    In http://www.linux-mtd.infradead.org/tech/nand.html, it is stated that
>
>    "if you have a bad block on your chip, just skip this block and copy
>    the data to the next block. JFFS2 is able to handle this gap.".
That's correct.

>    So, I write a program to skip the bad block, and copy the data to the
> next block. The missing file seems to appear on the file system now, the
> size looks correct. But when I diff the binary of the file to that of
> original, they are different and the binary failed to execute.
Strange.
Have you built your fs-image with the correct block size ?

>    I don't know much about jffs2 bad block handling, the only information I
> have is as mentioned above. Am I missing any other information ?
No

>    Is anyone manage to transfer an image to the nand device that has bad
> blocks without losing any files ?
Yes, I do

-- 
Thomas
________________________________________________________________________
linutronix - competence in embedded & realtime linux
http://www.linutronix.de
mail: tglx@linutronix.de

Re: Bad Block Handling in jffs2

[kokseng choo]

Hi Thomas,

Thanks for your reply.

Thomas Gleixner wrote:

>>   So, I write a program to skip the bad block, and copy the data to the
>>next block. The missing file seems to appear on the file system now, the
>>size looks correct. But when I diff the binary of the file to that of
>>original, they are different and the binary failed to execute.
>>    
>>
>Strange.
>Have you built your fs-image with the correct block size ?
>
  The command I used is as followed:
mkfs.jffs2 -p --eraseblock=16KiB -l -d ./jffsRoot -o jffs2.image
I changed the mkfs.jffs2 so that it allows me to create image with 16KiB 
erased size. I presumed it is not a problem to make the changed, but may 
be I was wrong. The raised the question about my changes sometimes ago 
in http://lists.infradead.org/pipermail/linux-mtd/2002-October/006273.html..
Please let me know, if my assumption is wrong.

>  
>
>> Is anyone manage to transfer an image to the nand device that has bad
>>blocks without losing any files ?
>>    
>>
>Yes, I do
>
>  
>
That sounds a lot more promising. Probably there is somthing wrong my 
configuration, I will look into my configuration again.

cheers
choo