[U-Boot] Switching CPU between SPL and non-SPL build

[Allen Martin <amartin@nvidia.com>]

Changing the subject line since this thread isn't really about
toolchains any more.

> > The problem I'm having with the SPL build is that a single entry in
> > boards.cfg can have exactly one architecture and CPU model. So
> 
> But you can define any tye of CONFIG_ settings, both in boards.cfg and
> in your board config file.
> 
> > there's no easy way to have the SPL build compile from arm720t and
> > the non SPL build compile from armv7. So I either have to have two
> 
> What would prevent you from extending the Makefiles to set build
> options depending on CONFIG_ settings from your board configuration?

What I really need is the ability to change "CPU" between SPL and non
SPL build.  This gets set too early for the board config file to
override.  What I really need is something like this in the generated
include/config.mk:

ARCH   = arm
ifeq ($(CONFIG_SPL_BUILD),y)
CPU    = arm720t
else
CPU    = armv7
endif
BOARD  = seaboard
VENDOR = nvidia
SOC    = tegra2

As an experiment I tried this, and it seems to do what I want.  I
don't see a clean way to do this without it being a hack or really
intrusive though.

-Allen

nvpublic