On Tuesday 25 September 2007 14:09,  wrote:
> 	Thank you! What I change is same to you, but now still has
> some questions, look below:
>
> ---
> /work/embedded_book_source/Development/yaffs2/yaffs_mtdif1.c  
>      2007-07-24 03:14:04.000000000 +0800 +++ yaffs_mtdif1.c   
>   2007-09-25 05:59:29.000000000 +0800 @@ -208,6 +208,9 @@
>         switch (retval) {
>         case 0:
>                 /* no error */
> +               etags->blockBad = (mtd->block_isbad)(mtd,
> addr); +               if (etags->blockBad)
> +                       return YAFFS_FAIL;
>                 break;

No, don't add it to the read function, it will slow down every
read of every page.  The test is only needed for each block
during the initial scan.  I added the call to the Query function
which is used during the scan.

> 	Another question:
>
> 		linux 2.6.22.6,
> 		yaffs_mtdif1.c's version is : "$Id: yaffs_mtdif1.c,v 1.2
> 2007/07/23 19:14:04 imcd Exp $" Flash Type: 512Byte/Page
>
> 	Even for yaffs1, the default nand_ecclayout of yaffs_mtdif1.c
> is: static struct nand_ecclayout nand_oob_16 = {
>   	          .eccbytes = 6,
> 	          .eccpos = {0, 1, 2, 3, 6, 7},
> 	          .oobfree = {
> 		        { .offset = 8,
> 		          . length = 8}}
>           };
>
> 	But the nand_ecclayout of utils/mkyaffsimage.c is:
> 	     static struct nand_ecclayout nand_oob_16 = {
> 	     	.eccbytes = 6,
> 	     	.eccpos = { 8, 9, 10, 13, 14, 15 },
> 	     	.oobavail = 9,
> 	     	.oobfree = { { 0, 4 }, { 6, 2 }, { 11, 2 }, { 4, 1 } }
> 	     };
>
>     They are diffrent, this is the reason my yaffs partition
> can be mount, but can't work: in
> nandmtd1_ReadChunkWithTagsFromNAND, 'retval =
> yaffs_CheckECCOnTags((yaffs_Tags *)&pt1)' is -1, so all blocks
> are treated as 'Empty'.

Yes, MTD changed the built-in/default layout policy between
2.6.17 and 2.6.18.  If you want backward compatibility you'll
have to change the layout -- and if you do, try adding it
to the platform NAND mapping code.  You will probably find you 
also need to replace the call to nand_scan() with two calls: 
nand_scan_ident(), then, after you override the default layout
(eg: chip->ecclayout = chip->ecc.layout = &my_nand_layout) call 
nand_scan_tail() to finish off.


> 	I use the second nand_oob_16 above, configure
> CONFIG_YAFFS_9BYTE_TAGS. And then the system can boot, the
> content in the yaffs root filesystem can be seen.
>
> 	The question is: it can't boot next time. After the first
> booting, I do nothing but run 'reset'.

You need to untangle the layout issues.  MTD can only really
do one policy for the whole chip - to boot images, bootloaders, 
yaffs etc., all have to agree as to the format/layout of 
oob/spare.

> 	The kernel log at the second booting is:
> VFS: Mounted root (yaffs filesystem).
> Freeing init memory: 124K
> Kernel panic - not syncing: No init found.  Try passing init=
> option to kernel.
>
> 	By the way, change the nand_ecclayout seem to be ugly, there
> is another partions on the nand flash, the ECC layout should
> be consistent to another tools, such as U-Boot. Do you have
> some idea? Thank you.

It's a big mess.  The user-space tools have a very poor idea of 
MTD policies.  We need new tools and a better design.

-imcd