Subject: Re: MTD devices in NetBSD
To: Charles M. Hannum <>
From: marty fouts <>
List: tech-kern
Date: 03/23/2006 15:31:50
On 3/23/06, Charles M. Hannum <> wrote:
> On Thu, Mar 23, 2006 at 02:22:48PM -0800, marty fouts wrote:
> > > This can have bad effects, e.g. for some flash systems which need to
> > > store data like bootloaders at a specific offset in flash.
> >
> > On NAND, you can't have a bootloader like that.  As a minimum, the
> > bootloader needs to be able to deal with bad block management.
> Not true.  (See my earlier reply about this.)

If you use a NAND part that guarentees a small number of good blocks
at the start and your boot image and loader all fit into the small
number of good blocks, then the boot loader doesn't need to deal with
bad block management.

My experience has been that typically the bootloader that fits into
such a small amount of space is a very simple stage-one bootloader for
a two stage boot process and the bad block management has to be done
in the stage-two loader. Even then, the first stage loader has to be
able to at least deal with skipping bad blocks as it loads the second
stage loader.

So, yes, I agree that what I said isn't entirely true. ;)