AW: [U-Boot-Users] das u-boot and disc on chip

Martin Krause Martin.Krause at
Thu Mar 3 08:39:22 CET 2005

Hi all,

u-boot-users-admin at wrote on :
> > I wouldn't put it like that. IMO your hardware is not the best
> > choice for you because it is missing a proper boot ROM (256 kB
> > flash  would be  just  perfect)  to  allow  you using a decent boot
> > loader without jumping in loops.
> I 100% agree that dealing with a separate NOR boot ROM is so
> much more
> easier. However, I also see booting from NAND data flash with a small
> boot readable sector is quickly becoming popular in lower cost/smaller
> footprint/less power consumption equipment.

In my understanding a main difference between NAND and NOR flashes is,
that in NAND flashes block integrity is not guaranteed. Thus blocks 
could become bad during lifetime. A software driver is needed to
keep track of this bad blocks and to backup data from a block
which went bad to a new valid block (similar to the bad sector 
management in hard disks).
With this fact in mind, I think it is not a good idea to store the
boot loader in a flash device whose data integrity is not guaranteed, 
even though it may be cheap and popular. Or am I missing something?


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