[U-Boot] Is it possible to boot the U-boot from the another U-boot from the flash area

[Schneider, Kolja]

Dear Ishwar Saunshi,
> >
> > I have gone through the FAQ section, this FAQ only talks about the
> > condition where the other Uboot is in RAM but what I am thinking is to
> boot
> > the Uboot from the flash location by another running Uboot.
> 
> This doesn't make any difference.  Read more carefully, and read to
> the end.  Pay special attention to the part here:
> 
> 	U-Boot expects to see a virgin CPU, i. e. the CPU state must
> 	match what you see if the processor starts executing the first
> 	instructions when it comes out of reset. If you want to start
> 	U-Boot from another boot loader, you must disable a lot of
> 	code ...
> 

This is really highly CPU-dependent. We are using something like that to 
implement a fallback u-boot image in case someone manages to kill
the standard image, it was quite easy to do for e.g. mpc512x, but quite some 
coding effort for mpc85XX. The corresponding code always looks 
slightly insane. If you feel like diving in deep into the innards of
your CPU, go for it. If you don't really need it, skip it.

:-) Kolja

> 
> Best regards,
> 
> Wolfgang Denk
> 
> --
> DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
> HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
> Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
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