Ian McDonnell,ÄúºÃ£¡

>> 	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.	

  My system is simple: CPU S3C2440, 1M NOR Flash, 64M, 512Bytes/page NAND Flash. 
U-Boot is on NOR Flash, it is used to read the kernel from NAND Flash and boot the system;
YAFFS is in another partition of NAND Flash.
  The method I change nand_ecclayout is simple too: 
just change the nand_oob_16 in drivers/mtd/nand/nand_base.c.
  So, the nand_ecclayout is consistent for allthing. ECC layout is only used in yaffs partition.

  Now, I has no idea why the yaffs root filesystem can't be used at the second booting,
who change it?




>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

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