[U-Boot-Users] How to use u-boot to load kernel and file system to one partition in NAND

Wolfgang Denk wd at denx.de
Thu Nov 2 23:27:51 CET 2006

In message <9BB2AECBBDD3E6499663C42C1DFD40AAE496C5 at PETWM02.calix.local> you wrote:
> I am trying to see if u-boot allows to have a single partition for both
> kernel and file system in NAND Flash.

Yes, you can do this. If it makes sense, depends on a lot of factors.
Usually it does not.

> Currently, I am looking at two possible approaches:
> 1. add an extra partition in the NAND flash and keep the second kernel
> in there and have some way in u-boot to decide which one to load.

That's the standard approach and  works  just  fine,  even  in  fancy
setups  like  bootcnt  triggered  automatic  fallback scenarios. It's
simple, and fast.

> 2. if u-boot allows, have one single partition for both kernel and file
> system and upload both kernel images and have a soft link to a kernel
> image.

I'm not sure if the softlink idea works, but you can just switch  the
image  filename in U-Boot. Works well, too, but is one of the slowest
ways to boot a system.

> I can't find a way to do the second option above, but that would be

Why not? It's a two-step procedure: first load the image to RAM, then
bootm it...

> ideal for field upgrade.  Has anyone tried either of these approaches or
> have any other idea of how to do this? I am new to using u-boot and
> linux.

I tend to disagree that it's "ideal". But it can be done.

Best regards,

Wolfgang Denk

Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
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