[ECOS] FAT32 over NAND

Himanshu Patel himanshup@aftek.com
Tue Jan 20 15:11:00 GMT 2009


Okay...Thanks...

YAFFS2 is not a possible option...As device should be able to access from PC
running Windows also through mass storage interface...

Can we make use of NFTL (NAND flash translation layer) which Linux is
providing? 

Regards,

Himanshu Patel

-----Original Message-----
From: Rutger Hofman [mailto:rutger@cs.vu.nl] 
Sent: Tuesday, January 20, 2009 8:15 PM
To: Himanshu Patel; 'eCos Discuss'
Subject: Re: [ECOS] FAT32 over NAND

Andrew Lunn wrote:
> On Tue, Jan 20, 2009 at 07:38:02PM +0530, Himanshu Patel wrote:
>> Hi,
>>
>> We want to have FAT32 file system over NAND flash. Is it possible? What
>> approach should we take for developing the same?
> 
> If you look back in the archive, last year there was some work to get
> YAFFS on NAND working. I would suggest trying to build on the NAND
> infrastructure that provided.

I implemented basic NAND flash functionality and a wrapper layer for 
YAFFS2, a file system designed specifically for NAND flash. For an alpha 
release (and maybe later on, beta release) of my code, see: 
http://www.cs.vu.nl/~rutger/software/ecos/nand-flash/

If you want FAT32, you will have to create (port from elsewhere?) a FTL 
(Flash Translation Layer) that implements lots of stuff to make FAT32 
behave in a NAND-compatible way. For a discussion of this in the context 
of UBIFS (the latest-greatest Linux NAND flash file system), see:

http://www.linux-mtd.infradead.org/doc/ubifs.html#L_raw_vs_ftl

An FTL should minimally provide:
- wear levelling
- garbage collection for released blocks
- bad block management
- write caching because programming has to be consecutive and in at most 
a few operations.

YAFFS2 implements all this already. Is using YAFFS2 an option, maybe?

Rutger Hofman
VU Amsterdam




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