[U-Boot] Boot uboot from another position in flash

[ich <contumax@gmx.at>]

Am Mittwoch, den 03.08.2011, 21:21 +0200 schrieb Wolfgang Denk:
> Dear ich,
> 
> In message <1312383540.4776.36.camel@debian> you wrote:
> > 
> > I know that. But I am not able to port for sh platform to a newer
> > u-boot.
> > 
> > > Please note that U-Boot v1.3.1 is about 4 years old and as such no
> > > longer supported here.
> 
> Your quoting style is strange.  Normally the reply _follows_.
> 
> Well, if you cannot update, then we cannot help it either.  It's yur
> problem, after all.
> 
> [Well, of course there are companies that will happily send you a
> quotation for such an update, in case you are considering a commercial
> solution.]
> 
> > > U-Boot is, in it's default configuration, designed to be run on a
> > > virgin CPU comingg fresh out of reset, so it naturally has to be
> > > installed at the reset vector of your processor. In addition to the
> > > start address, many parts of the initialization code expect to find a
> > > vorgin, uninitialized system.  Such parts must be disabled when you
> > > want to change the conditions under which you want to run U-Boot.
> > 
> > I read this several time in the net, but found no solution.
> > I know it is possible, because I saw it in a flash hex-file, but can't
> > reproduce it.
> > I thought changing CFG_MONITOR_BASE / CFG_RESET_ADDRESS would do it.
> 
> As mentioned, this is NOT sufficient.  See also the FAQ.

It is absolutly not necessary to change CFG_MONITOR_BASE /
CFG_RESET_ADDRESS !

> 
> > Do you say it's not easily possible to boot u-boot from another flash
> > address even with a newer u-boot????
> 
> It is possible, and it is not so difficult if you have sufficient
> experience with U-Boot.
> 
> > Do I have to make big changes to the uboot-source (start.S,..)?
> 
> This depends on your definition of "big".  Judging from the questions
> you are asking, I tend to say: too big for you.  No offence meant.


There is no need to change anything in u-Boot source for my platform.

Judging from the answers you give, I tend to say: Don't answer
questions, wich are too big for you.



> > I could put ~256 bytes of assembly code to the reset-vector at
> > 0x0A000000 and jmp in the u-boot; but if you say this is not enough, I
> > will not start to learn the assembly language for my processor.
> 
> This has nothing to do with using assembly code.

It was only an assembly code problem.

I can now start U-Boot from every position in flash I want.


contumax