Re: OOB questions

Jason Liu
2008-10-07T04:04:35Z

2008/10/7 Curt Scott <curt_scott@yahoo.com>:
> Hi,
>
> I am writing a MTD NAND (2K page) driver module for Linux 2.6.23.
> My NAND hardware controller performs all the ECC control
> under-the-hood. Although is has OOB bytes available there are some
> limitaitions...
>
> L1.) Page data and OOB data must be written at the same time.
Not only your NFC but also some others require to written page data
and oob data
at the same time espically for large page size nand flash since it use oob to
store the ECC data.
> L2.) OOB data is limited to 16 bytes / page (of a 2k page).
>
It should be ok for jffs2 filesystem.

> I have some questions about the OOB requirements for MTD/JFFS2 combo.
>
> Q1.) Does MTD/JFFS2 require the ability to read/write OOB bytes?
> Or can the system be set up operate with no OOB available?
jffs2 can work without oob.
> Q2.) Is it a requirement for OOB and non-OOB writes to happen independently?
>
May provide the interface to MTD layer. For MLC Nand flash, it's
impossible to write data and oob indepently since NOP is 1.
The file system should take care not to write it without erase it for MLC.

> thank you for you help,
> Curt
>
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