[U-Boot] Executing U-Boot from Another Boot Loader

[Wolfgang Denk]

Dear Roy Caspi,

In message <F977EFBA9BBA814EA37842E54344726D28664400 at TLRD-MAIL.Telrad.co.il> you wrote:
> 
> I have a VxWorks Boot Loader running on my P3041 and from there I'm willing to execute a U-Boot image that was previously burnt in my flash.
> The U-Boot image - u-boot-p3041ds-2011.09-r5.bin - is 512KB and is burnt at the address of 0xF802,0000, ending at 0xF809,FFFF (no env. parameters were burnt).
> So from the VxWorks Boot Loader I branch to the address of 0xF802,0000 and get an exception. I also try branching to 0xF809,FFFC, but again the U-Boot shell won't show up.
> Could you please help me on that? Where can I find the U-Boot entry point and how should I load it "manually"?

U-Boot expects to be run on a CPU that comes fresh out of reset, i. e.
it starts at the reset entry point.  You must modify the code (more or
leass heavily) so that allt he things that were already done get
skipped.  Some board have a "RAMBOOT" config option where you could
check what needs to be done.

But then - is it worth it?  Just install U-Boot and let it do it's
work.  U-Boot can also boot VxWorks, so there should be no need to
keep the old loader.

Best regards,

Wolfgang Denk

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