Boot from NAND flash ???

[Vadim Khmelnitsky]

[Thomas]
There's another important limitation. Who guarantees you, that your 
"boot-page" does not get bad or is a bad block already. That's the reason, 
why DOC has 4 blocks with the same code.

[Vadim]
Actually, in Diskonchip Millennium 8MB we have first erasable unit
guaranteed to be good .
We do have two copies of a boot-code stored one after another in page 0 and
1 of the first erasable unit .

Vadim

-----Original Message-----
From: Thomas Gleixner [mailto:gleixner at autronix.de]
Sent: Mon, May 13, 2002 4:19 AM
To: manningc2 at actrix.gen.nz; David Woodhouse;
franck.fleter at netbricks.com
Cc: linux-mtd at lists.infradead.org
Subject: Re: Boot from NAND flash ???


On Monday, 13. May 2002 12:11, Charles Manning wrote:

> There are however two mechanisms to get around this:
> * Some people and micros implement a "data pump" state machine to extract
> an executable sequence from a NAND device.
> * Some of the newer NAND devices can be accessed directly from the bus and
> can do the job of a boot ROM.
>
> There is however a limitation to both of these. The NAND can only be
> accessed sequentially (it is not random access like NOR) which limits the
> types of instruction the boot code can perform. In particular it can't
> branch or fetch from elsewhere in ROM.

There's another important limitation. Who guarantees you, that your 
"boot-page" does not get bad or is a bad block already. That's the reason, 
why DOC has 4 blocks with the same code. 

-- 
Thomas
___________________________________
autronix automation GmbH
http://www.autronix.de gleixner at autronix.de

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