Preventing JFFS2 partial page writes?

[Peter Barada]

On 06/22/2011 04:06 PM, Ivan Djelic wrote:
> On Wed, Jun 22, 2011 at 08:17:33PM +0100, Peter Barada wrote:
>> On 06/22/2011 01:07 PM, Ivan Djelic wrote:
>>> On one hand it sure would be nice (and a bit complicated) to accurately
>>> describe OOB write constraints, for easier JFFS2/YAFFS2 integration.
>>> On the other hand, I am not sure such a complication is really worth the
>>> trouble, given that on next nand generation:
>>> - OOB areas will not be usable anymore for metadata storage (8-bit ecc leaves
>>>     only 6 spare bytes out of 64)
>>> - partial writes will probably be limited to 1 (like in MLC), meaning that
>>>     JFFS2 clean marking step will be forbidden anyway
>>> Furthermore, userspace will probably need to handle case 3) anyway (no
>>> protected oob bytes) to stay portable...
>>>
>> SLC parts (including this one) look to be around for a while, as well as
>> the products they are already in.  So I think the issue of JFFS2's
>> cleanmarker in the context of this Micron NAND needs to be solved,
>> preferably in a general way so the next oddball NAND chip that comes
>> along doesn't cause MTD, mtd-utils, JFFS2 (and other NAND FS) fits.
>>
>> Does UBIFS do any of the "partial writes" (i.e. write OOB/data area
>> multiple times) as JFFS2 does?
>
> No it doesn't. UBIFS relies on UBI, which itself does not rely on oob for
> storing metadata. BTW, have you considered using UBIFS instead of JFFS2/YAFFS2?
Yes.  However customers are already using JFFS2/YAFFS2 and are reluctant 
to change.
> --
> Ivan
>
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-- 
Peter Barada
peter.barada at gmail.com