Re: nand flash

>>> I've ported NetBSD to Mesa Electronics 4C81 PC104plus SBC.  The storage
>>> is 32MB/64MB bare NAND which holds BSDFFS.

>> How do you handle the bad blocks that develop as the device "wears" ?

Could LFS be more appropriate for 'wear levelling' ?
Especially now that we can use it as root filesystem...

// Yocto


----- Original Message ----- 
From: "Toru Nishimura" <[email protected]>
To: <[email protected]>
Sent: Thursday, October 04, 2007 10:00 PM
Subject: Re: nand flash


> David Young  asked;
>
>>> but the decision was made weighing "the rootfs is
>>> seldom written beyond configuration mods by administrators."  Software 
>>> ECC
>>> is always calc'ed and verified, block write is counted and recorded 
>>> inside
>>> NAND spare fields.
>>
>> How do you handle the bad blocks that develop as the device "wears" ?
>
> The answer is "by manual intervention," just like good-old-days Winchester
> style hard disk drive bad sector management practice.  I wrote a cmdline
> tool to manage bad block list and relocate block contents.  In principle 
> we
> neglect the whole NAND woe/buzz to happen due to the above mentioned
> rational.  "this tools may cause hazardous results to hurt you, trained 
> service
> personel only, or don't use this."
>
> If I have chose MMC/SD/CF media to go, I would build vnd on a large file
> on the FAT filesys and forget how good/bad to gauge badblock and
> wear-leveling schemes inside.
>
> Toru Nishimura/ALKYL Technology
>