[U-Boot] commit "powerpc: Remove warm reset entry point" does not work on mpc83xx

[Joakim Tjernlund]

Peter Tyser <ptyser at xes-inc.com> wrote on 2010/10/19 20:39:41:
> 
> > > > It seems like my board uses the warm start vector at all times.
> > > > Padding with 4 nop's after the _start symbol fixes the problem.
> > > > It might be due to a somewhat peculiar reset design but I cannot 
> > > > understand
> > > > why. Does this work for everyone else using 83xx?
> > > 
> > > Odd...  I don't have an 83xx board to test on unfortunately. Nothing
> > > jumps out as being obviously wrong in the assembly:
> > 
> > The difference is that I suspect execution starts at 0xXXXXXX110 
rather
> > than 0xXXXXXX100. BTW, I have my reset vector at 0x0
> > 
> > What causes a warm reset?
> 
> My understanding is that a warm reset on the 8xxx CPUs isn't really a
> hardware reset - its just when code explicitly jumps to the warm reset
> entry point.  For example, this board used to jump to _start_warm when
> "reset" was ran in U-Boot: 
> 
http://git.denx.de/?p=u-boot.git;a=commitdiff;h=3792d7436e2bf881b6abdede5a481a62b5dedd55

> 
> During normal use I thought that the reset entry point was always
> 0xXXXXX100 and a warm reset would never occur.

I am not so sure about this. Perhaps the Freescale guys can set us 
straight?

> 
> What is the power on reset process like on your board?

A bit fuzzy ATM, will have to look at that.