[Yaffs-archive] RE: bad block problem

The last line:
> 200h:ff ff ff ff 00 00 ff ff ff ff ff ff ff ff ff ff
is the spare area (oob, redundancy, ...) and refers to yaffs_Spare structure (defined in yaffs:guts.h file).

// Spare structure
typedef struct
{
    __u8  tagByte0;
    __u8  tagByte1;
    __u8  tagByte2;
    __u8  tagByte3;
    __u8  pageStatus;     // set to 0 to delete the chunk
    __u8  blockStatus;
    __u8  tagByte4;
    __u8  tagByte5;
    __u8  ecc1[3];
    __u8  tagByte6;
    __u8  tagByte7;
    __u8  ecc2[3];
} yaffs_Spare;

So the two 0x00 bytes are pageStatus and blockStatus.
pageStatus 0 means that the page is deleted (so ready to be used without a new erase command)
blockStatus 0 means that the block has been retired (marked bad) or is a factory marked block

From what I can see from source code, the only way to have such values are:
- the Factory has marked this block bad (could happen on some devices/manufacturer)
- yaffs has marked this block with the function yaffs_RetireBlock

The second case (the only that depends on yaffs code) could happen if there's an erase error; the reason of this error could vary depending on your flash interface, noisy environment, EM, etc.

I suggest you to enable yaffs trace (search for #define T(x)) and look at debug message to better understand your fs operations.

I also suggest to erase all your flash memory before mounting yaffs because I can't really figure how it can menage a badly formatted chip (perhaps this is the real problem).

Just to know, what kind of flash device are you using?
What's the OS?

Regards
Adamo



> -----Original Message-----
> From: Skumar [mailto:skumar@mistralsoftware.com]
> Sent: lunedì 19 aprile 2004 14.18
> To: yaffs
> Subject: bad block problem
>
>
> hi,
> has someone faced the problem where yaffs has marked many blocks bad?
> for me yaffs has marked almost 70% blocks bad.
> below i am attaching the data of page 0 of a block which is marked bad
> this is the data in the all pages of blocks which are marked bad
> notice the last row ***
>
> help needed
>
> Regards
> sharath
>
> 0h:ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> 10h:ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> 20h:ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> 30h:ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> 40h:ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> 50h:ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> 60h:ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> 70h:ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> 80h:ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> 90h:ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> a0h:ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> b0h:ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> c0h:ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> d0h:ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> e0h:ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> f0h:ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> 100h:ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> 110h:ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> 120h:ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> 130h:ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> 140h:ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> 150h:ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> 160h:ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> 170h:ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> 180h:ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> 190h:ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> 1a0h:ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> 1b0h:ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> 1c0h:ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> 1d0h:ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> 1e0h:ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> 1f0h:ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> 200h:ff ff ff ff 00 00 ff ff ff ff ff ff ff ff ff ff
>
>


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