[U-Boot] [PATCH 2/2 RESEND] SPL: Allow user to disable CPU support library

[Scott Wood <scottwood@freescale.com>]

On 09/16/2011 05:48 PM, Marek Vasut wrote:
> On Saturday, September 17, 2011 12:07:52 AM Scott Wood wrote:
>> You have no idea why I'd like to be extremely selective with what I
>> include in a 4K binary?
> 
> That I do understand -- but that kind of selection is there.
>>
>> It's not about avoiding particular files.  It's about including
>> *nothing* but what is explicitly asked for through some SPL-specific
>> CONFIG symbol.  Maybe that includes everything in arch/$(ARCH)/cpu.
>> Maybe it includes nothing in there.  More likely, it includes just a
>> fraction of it.
> 
> The stuff in arch/arm/cpu should be exactly what you need, nothing more !

This is "spl/", not "arch/arm/spl/", so let's not reason from one
architecture, much less the subset of that architecture that has already
been made to work with spl/ -- there are 14 different instances of
arch/arm/cpu/$(CPU).

We will not want everything we normally pull from
arch/powerpc/cpu/mpc85xx to go into an 85xx NAND SPL, for example.  But
we will want some small portion of it.

My understanding of how spl/ is meant to work is that each directory's
makefiles will use special SPL config symbols to decide what individual
objects (if any) to include.  It's not clear to me why we need a
directory-level control.  Maybe it would be the most convenient way to
implement it for something that is well-encapsulated and arch-neutral
(thus only one instance to worry about), where the odds of a subset
being useful are slim, but it doesn't seem appropriate here.

Whether it's file or directory based, everything should be off by
default.  Boards should ask for what they want, not what they want to
exclude.

-Scott