Subject: Re: MTD devices in NetBSD
To: Charles M. Hannum <mycroft@MIT.EDU>
From: Garrett D'Amore <>
List: tech-kern
Date: 03/23/2006 14:41:41
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.)

But if you've hidden away the mapping with some kind of block remapper,
you don't have a good way to write those blocks.

Anyway, I'm afraid this discussion is starting to degenerate into a
worry about the problems with NAND, and why you "can't" do what I want
to do with NAND.  I need to do those things with NOR.

So I'm going to provide a framework that works with NOR.  It will be up
to someone else to do a NAND conversion layer.  My gut feeling is that
boards with NAND on them are less interesting at the moment than those
with NOR.  The systems that use NAND are likely to have the NAND part
locked away behind a USB or CompactFlash adapter.

If someone believes differently, and that I really do need to be trying
to address NAND, please speak up now and let me know how to do so.  At
the moment I want to move forward with NOR before I get discouraged with
the problems regarding NAND.

Garrett D'Amore, Principal Software Engineer
Tadpole Computer / Computing Technologies Division,
General Dynamics C4 Systems
Phone: 951 325-2134  Fax: 951 325-2191