Re: [RFC] read-only filesystem support for NAND flash devices

Russ Dill
2006-05-11T23:27:07Z

> > Free block list? Bad block list? Tracking of block numbers? Sounds
> > like a full on FTL to me.
>
> A full read-write FTL needs to handle 512-byte writes if it's going to
> pretend to be a normal block device. A simple FTL for read-only stuff
> like cramfs/squashfs doesn't need that.
>
> We should probably do this kind of thing as an FTL -- we already have
> the 'mtd_blkdevs' infrastructure to help you by doing most of the
> interfacing to MTD and block layers for you. And then you can use any
> read-only file system on it.

True, I also realized another possible shortcut. If a blocks gets an
ECC correction on a read, rewrite it to a free block, erase the block,
rewrite it from the data written to the free block, and then erase the
free block. You'd need to put some info in the OOB so you could know
what the state is on power recovery.