NAND partitioning

[Josh Boyer]

On Mon, 2005-01-31 at 16:29 +0100, Jörn Engel wrote:
> 
> Not sure if there really is a problem that needs solving.
> 
> Your concern is that you need R blocks for the raw data, pick an
> arbitrary number A of blocks, but notice that A-R is less than B, the
> number of bad blocks in the area.  Sure.
> 
> So now you simply pick a sufficiently large A.  Let's say that your
> flashes have 5% bad blocks on average.  I'm too lazy to do the math
> properly, but if you pick A = 1.2*R, then well over 99% of all flash
> chips should have less than 20% bad blocks in you boot partition.

Blocks go bad during usage, and data sizes change.  Also, often times
one is given a specific chip size and told "make it work".  That can put
some more restrictions on how large of a static partition you can make
for a given set of data.

> 
> And for the remaining 0.something%, you are the one to argue why those
> chips have a sufficient quality to hit the field.  I'd be scared.

I don't make those decisions.  But when something goes bad, and
something always does, I have to deal with it.

josh