Messages in this thread | | | Date | Wed, 4 Feb 2009 22:32:11 +0100 | Subject | Re: mmotm 2009-02-02-17-12 uploaded (x86/nopmd etc.) | From | Andrea Righi <> |
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On Wed, Feb 4, 2009 at 10:25 PM, Andrew Morton <akpm@linux-foundation.org> wrote: > On Wed, 4 Feb 2009 21:08:46 +0100 > Ingo Molnar <mingo@elte.hu> wrote: > >> >> * Andrew Morton <akpm@linux-foundation.org> wrote: >> >> > > > This is getting painful. >> > > >> > > 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! ;-) >> > > >> > > 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. >> > >> > I like this one. The mixing up of declare-something with use-something >> > is often the source of our woes. >> >> yes. I mapped this problem area once and this is how the include file >> spaghetti gets generated in practice: >> >> - type A gets declared >> - type A gets _used_ in the same file in an inline method, BUT, >> >> that usage also brings in instantiated use of type X1, X2 and X3. >> >> if all types are declared like that everywhere, it can be seen (and it's a >> mathematical certainty) that the only conflict-free way of doing this is to: >> >> - initially add random #include lines to bring in type X1, X2 and X3. >> Which brings in recursive dependencies from those X1 X2 and X3 files. >> >> - when the stuff hits the fan then folks are in a big mess already and >> only a deep restructuring could gets them out of it - which they rarely >> do in an iterative environment. So they work it around iteratively: >> instead of new nice inline methods [which we really prefer] they delay >> all the 'usage' instantiation to .c file via the use of CPP macros >> [which we hate because they hide bugs and cause bugs]. > > None of which would happen if we didn't also have an inlining fetish. >
So, about the pmd_* functions, why not move the nopmd implementations in mm/memory.c (for example) always with the #ifndef's, and move the specific arch implementations in arch/../mm/pgtable.c (for example)?
-Andrea
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