Re: Build system adjustments for subarchs

[Rob Landley <rob@landley.net>]

On 08/13/2013 08:06:17 PM, Rich Felker wrote:
> Hi,
> 
> I'm looking for some ideas on a problem in the build system: how to
> cleanly share asm between subarchs. The problem is this: ARM, and
> possibly other archs in the future, has multiple dimensions of
> subarch: little-endian(default) vs big-endian, and
> fpu-agnostic(default) vs hardfloat. The asm requirements are:
> 
> - MOST asm is shared by all subarchs.
> 
> - A small amount of asm (for now, just memcpy) is endian-specific but
>   has nothing to do with floating point ABI.
> 
> - A fairly significant amount of asm in the future will be hard-float
>   specific (optimized math functions and floating point environment)
>   but has nothing to do with endianness.

If there's no actual overlap it sounds like you're describing search  
paths you stick stuff at the front of. Have hardfloat specific .S bits  
in one dir, differently endian stuff in another dir, and the truly  
agnostic stuff with default versions of everything in a third, then  
thread a search path through 'em.

> What I don't like about this approach is that the logic for the names
> to use in steps 1-3 has to go either in the configure script or the
> makefile. The makefile is not intended to have this sort of arch
> logic, but instead to derive the logic from the source tree structure.

How you get a makefile to do _anything_ is not my department. (Horrible  
language, make. Imperative or declarative, PICK ONE.)

Rob