[U-Boot-Users] 2-step U-boot(?)

[Stefan Roese <sr@denx.de>]

On Monday 09 June 2008, Frank Wei wrote:
> I'm new to u-boot. Has anybody tried to make 2-step u-boot? I mean a really
> small u-boot (the first u-boot) possible only needs to initialize the CPU,
> memory... and load the full featured (the second u-boot) u-boot and the
> Linux to the RAM. In this way the second u-boot as an application can be
> updated on the fly.
>
> Could you please share your knowledge here If you have done the job or the
> similar?

Yes, there already is a framework for a 2-stage U-Boot booting in place. Take 
a look at the nand_spl (NAND Secondary Program Loader) infrastructure:

nand_spl/*
doc/README.nand-boot-ppc440

Here a small (4k) image is build which only inits the basic CPU stuff, RAM and 
NAND controller. Then a full-blown U-Boot image is loaded from NAND.

Best regards,
Stefan

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