Re: [Qemu-devel] [PATCH for-2.8?] rules.mak: speedup save-vars load-vars

[Paolo Bonzini]

On 02/11/2016 17:40, Daniel P. Berrange wrote:
> Could we instead just do:
> 
> Makefile.objs:
> 
>   util-obj-y =
>   include util/Makefile.objs
> 
> util/Makefile.objs:
>   util-obj-y += util/osdep.o util/cutils.o util/unicode.o
> 
> Yes, you now get the "burden" of adding a directory prefix onto the file
> paths, but I don't think that's a big deal, as it is only a one-time
> cost when you create a new file, or very rarely move files between dirs.

I don't think the simplification would be that much.  In particular,
note that you would keep some of the complication to process *-cflags,
*-libs and *-objs variables, and you would have additional complication
to handle the prepending of ".." in Makefile.target.

Paolo

> Without the unnest-vars black magic I think it'd be simpler for mere
> mortals to understand what is happening in the makefiles, lowering
> the barrier to entry for new contributors to QEMU (and even existing
> QEMU contributors who've not had the misfortune of debugging our
> recursive make system yet)
> 
> Regards,
> Daniel
>