[U-Boot] Running vanilla u-boot v2012.10 on Guruplug

[Albert ARIBAUD <albert.u.boot@aribaud.net>]

Hi Dirk,

On Sat, 12 Jan 2013 20:41:36 +0100, Dirk Heinrichs
<dirk.heinrichs@altum.de> wrote:
> Am Samstag 12 Januar 2013, 16:51:51 schrieb Wolfgang Denk:
> 
> > Did you read the FAQ?  Especially
> > http://www.denx.de/wiki/view/DULG/CanUBootBeConfiguredSuchThatItCanBeStarted
> > InRAM ?
> 
> Now I did :) Thanx a lot.
> 
> Interesting that [1] states it's possible, though...
> 
> Bye...
> 
> 	Dirk

My experience with starting U-Boot from RAM is that it's usually
impossible when U-Boot is meant to start directly from FLASH, mostly
(but not only) because the code at some point will rely on being able to
keep on running even through access to DRAM is not possible.

Now, starting U-Boot *may* be possible when U-Boot is loaded in DRAM
before starting it, but is a very tricky and undependable process. For
instance, on the Wireless Space target I am maintaining, and which is
supposed to be preloaded from FLASH into DRAM by a ROM monitor, if I
start the OpenOCD server, then in the console, do a break and / or a
reset halt, I won't be able to load_image u-boot; whereas if I do the
same actions as -c options when launching OpenOCD. And I have checked
countless times that the DRAM init sequence in the config file is
bit-for-bit identical to that used by the KWB which wraps the U-Boot
image, and which boots fine on its own.

Amicalement,
-- 
Albert.