[Yaffs] News about my Yaffs & memory space problems... RESOLVED

[Ludovic Guilhamat]

Charles Manning a écrit :

>On Tuesday 09 August 2005 00:26, Ludovic Guilhamat wrote:
>  
>
>>Hi,
>>
>>I found some  other clues about my problem, but I didn't fully manage it
>>yet...
>>
>>Brief summary : I want to use yaffs on linux-2.4.22 kernel with uClinux
>>(m68k coldfire), and with the MTD of the 2.4.22 kernel. (I attempted to
>>backport a newer MTD, but without success for the moment). My Flash is a
>>Samsung 16Mb Nand.
>>    
>>
>
>Part numbers please. Different parts have different properties.
>
>
>  
>
>>So, my problem occurs when I erase a file on my 2Mb partition. More
>>precisely, it occurs when I want to copy/create some other files. Hence,
>>I think it's the garbage collect process that is the source of my
>>problem on my system. 
>>    
>>
>
>In almost all cases, problems that arise during gc are cause by one of:
>1) flash geometry issue. The block size you have specified in yaffs or mtd 
>does not match the physical hardware.
>2) Some issue with ECC or low-level NAND access functions.
>
>
>
>  
>
>>Here is the log: 
>>
>>* after erasing the file :
>>
>>yaffs locking
>>___________ really free is 3033, pending 1001, nFree is 4034
>>yaffs unlocking
>>
>>* When I want to recreate a file after an unmount / mount :
>>
>>nand_read_ecc: from = 0x00909e00, len = 512
>>nand_read_oob: from = 0x00909e00, len = 16
>>nand_write_oob: to = 0x00908000, len = 16
>>nand_write_oob: Failed write verify, page 0x00004840     <----- This
>>corresponds to the (falsely) damaged marked blocks that I see when I
>>nand_write_oob: to = 0x00908200, len = 16
>>nand_write_oob: Failed write verify, page 0x00004841     <----- want to
>>format my partition.
>>    
>>
>
>You need to turn off write verification in the mtd and do that in YAFFS 
>instead.
>
>  
>
>>* Finally, here is the interesting part of 'cat /proc/yaffs' :
>>
>>nPageWrites........ 10
>>nPageReads......... 181
>>nBlockErasures..... 0
>>nGCCopies.......... 0
>>garbageCollections. 3     <----- It seems that at each garbage
>>collection, 8Kb are used on my partition (is it normal ?). Then,
>>passiveGCs......... 3          <----- I find 104Kb used, instead of 80Kb...
>>nRetriedWrites..... 0
>>nRetireBlocks...... 3
>>    
>>
>
>Retired blocks == blocks that YAFFS has decided went bad and then marked bad. 
>This is most likely caused by a mismatch between YAFFS and mtd, most likely 
>in either the ECC or similar area.
>
>-- Charles
>  
>
Hi,

I finally resolved my problem...

My Nand Flash is a Samsung K9F2808U0C which needs the defaults 
parameters in Yaffs (512 bytes per chunk, 16 bytes for spare area and 32 
chunks per block).

I think my problem was that I hadn't included some configuration options 
in my Config.in... : the linux file caching layer, the 'use object 
header size' and the 'Turn off debug chunk erase check'. I hadn't port 
these config options because I wanted to port little by little the yaffs 
on my linux tree. But now, with the first two options activated, it 
works well.

Thanks and regards.
Ludovic.