RE: [9fans] disk/^(mbr format fdisk prep)

["Nigel Roles" <nigel@9fs.org>]

> Reading some linux docs (jffs,jffs2,yaffs), it seems the load
> leveling is a function of the file system/driver, not firmware.
>
>

This depends entirely on the technology involved. There are
intelligent flash systems (CF, SD, MM) which emulate disk
drives (e.g. CF can be connected directly to an IDE controller);
these do the wear levelling themselves.

Then there are the unintelligent technologies (NOR flash,
NAND flash, SmartMedia, SSFD) which don't.

Of course, the intelligent ones are built out of the
unintelligent ones with a controller in the way.

There are really only two kinds of flash; NOR and NAND.
The latter does it on 2 transistors per cell; the former
4. The latter is faster to program and erase, but loses
storage faster with age.

SmartMedia/SSFD is just a fancy name and packaging
for NAND flash.

So, jffs/jffs2/yaffs are designed to work direct onto
NOR/NAND flash, hence they have wear-levelling. It is
particularly important to do this for NAND flash for
a variety of reasons I shan't bore with.

Nigel