Re: [PATCH 00/22 take 3] UBI: Unsorted Block Images

Thomas Gleixner
2007-03-26T10:02:45Z

On Mon, 2007-03-26 at 10:45 +0100, David Woodhouse wrote:
> On Mon, 2007-03-26 at 03:04 +0200, Jörn Engel wrote:
> > That limitation stems from ECC and ECC is done in software. Currently
> > everyone and his dog is doing ECC in chunks of 256 bytes on NAND. So
> > your minimum write size is 256 bytes _if you care about ECC_. If you
> > don't care, you can write single bits on NAND, just as you can on NOR.
>
> No, on NAND flash it's a limitation of the hardware. The number of write
> cycles you can perform to a given page is limited. Exceed it and the
> contents of that page become undefined due to leakage, until you next
> erase it.

Right and you cannot write to random locations in a page. The write
chunks have to be in consecutive order. If you write 0xAA to offset 0,
you cannot rewrite it to 0x00 later without risking corruption.

tglx