[U-Boot] CONFIG_SYS_XIP_BOOT for when it's a choice?

[Wolfgang Denk <wd@denx.de>]

Dear Tom,

In message <20140407190210.GK23803@bill-the-cat> you wrote:
> 
> > I think CONFIG_ENV_IS_IN.. is an independent thing. Even when booting
> > from NOR you can have the environment anywhere else.
> 
> Well, maybe.  I'm not sure (and too lazy to dig through the board doc
> atm) on if you can have both NOR and QSPI available on the reference
> design, but I think not.  But also, for ..._qspiboot I want to show
> everything from QSPI, and ..._norboot I want everything on NOR.

OK, but this is a design decision for this specific board, then.  It
is not a fundamental property of the U-Boot design.  For us, boot
device and environment storage are independent.  And so it should be
implemented.

> > As for the differences between NOR and QSPI...  IIRC we cannot execute
> > any code directly on QSPI, we have to load it to some memory first,
> > right?  So QSPI is not much different from loading the code from any
> > other storage device - or am I missing something?  How is XIP from
> > QSPI working?
> 
> Nope, this board has memory mapped QSPI and on reading something other
> than all 0s or all 1s ROM jumps to it.

If you use the memory mapped mode, then it looks just like any
other ROM, and we should not need special code either.

Best regards,

Wolfgang Denk

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