[SPAM] FAT on NAND
Jim Zeus
jimzeus at vip.sina.com
Sun Apr 6 23:32:35 EDT 2003
> > What I am doing now is to build a filesystem which can be
> > recognized on _raw_ NAND flash. So, I think FAT will be the only
> > choice(though I know it's very unstable). And I have following question
> > now:
> For what ? Why don't you use JFFS2 or YAFFS, which handle NAND out of the box
> ?
Because I've got to build a FS which can be accessed by Windows and Linux at the same
time.I think JFFS2/YAFFS can't be recognized by Windows nowadays.
And , it seems like I have to support some device layer between the FS and Flash so the
Linux can access it, isn't it?
Is there anyway else I can choose?
>
> > 1.How unstable would it be? Does it support:
> > a.journaling (crash/power-off safe ,I mean)
> > b.bad block management
> > c.wear levelling
> > d.error correction
> > e.something else I dont know to make the FS reliable
> JFFS2 and YAFFS have all this, read the source and build a new one, if you
> have enough time.
Are all the functions supported by JFFS2/YAFFS? Somebody told me the wear levelling
is supported by MTD
And It seems like I don't have enough time ,maybe I can finish it with all my leisure time.
> > 4.Everybody tells me that the Fat on a NAND is not reliable,but I
> > think USB mass storage are based on NAND and got a FAT (or some
> > filesystem which windows can recognize) on it, so ,how comes it
> > happen?
> Yes, this is Smart-Media-FAT, which is not exactly the same as DOS-FAT.
> SmartMedia-FAT is used on SmartMedia cards for MP3-Players, Digicams ...
> There exist various adapters (USB, serial, LPT) to access it via a PC.
> SmartMedia-FAT is designed for NAND-FLASH and handles bad block management
> and error correction.
> If you want compability to this, you have to write a fs-driver, which is
> compatible to the SMART-Media-FAT definition, which is available from Toshiba
> under a non disclosure aggreement.
Does the SMART-Media-FAT build directly on a _bare_ NAND Flash ?
If it is, That's nothing useful to me 'cause Linux cant access it.
Thanks a lot for answering my questions
Your Faithful
Jim Zeus
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