Re: mmotm 2009-02-02-17-12 uploaded (x86/nopmd etc.)

[Jeremy Fitzhardinge <jeremy@goop.org>]

Ingo Molnar wrote:
> the include file spaghetti is ... interesting there, and it's historic.
>
> I could blame it on highmem, PAE or paravirt - but i'll only blame it on 
> paravirt for now because those developers are still around! ;-)
>   

Hey, don't forget unification, if we're pointing fingers ;)

> Jeremy, any ideas how to reduce the historic dependency mess in that area?
> I think we should go on three routes at once:
>
>  - agressive splitup and separation of type definitions from method
>    declaration (+ inline definitions). The spinlock_types.h / spinlock.h 
>    splitup was really nice in solving such dependency problems.
>   

That already exists to some extent, though I don't think it's being used 
to maximum advantage (pgtable-[23]level.h vs pgtable-[23]level-defs.h).  
For consistency we'd have  pgtable-4level(-defs).h headers too, and 
top-level pgtable.h/pgtable-defs.h headers.  But its not clear to me 
that would even be enough...

>  - uninlining of methods: instead of macro-ing them - wherever possible. 
>    It's really hard to mess up type + externs headers - while headers with 
>    inlines and macros mixed in get painful quickly.
>   

Yes.  I went through a period of fairly aggressive inline->macro 
conversion, and in many cases the remaining macros are there to #include 
hell.

>  - removal of spurious pile of dozens of #include lines in header files.

Yeah, it would be useful to make sure that each header only #includes 
the bare minimum headers to satisfy its own definitions - but of course 
that's going to provoke a long series of #include whack-a-mole patches.

    J