Re: configure speedup proposal: add --assume-c99 and --assume-posix2008 flags

[Thomas Petazzoni]

Dear Rhys Ulerich,

On Fri, 6 Jun 2014 10:14:41 -0500, Rhys Ulerich wrote:

> Granted, configure time does add up if one builds 10s of packages in
> sequence.  Is there some reason configure caches are unsuitable to
> gain speedup there?  I see almost a six-fold configure improvement on
> grep-2.20 when its working from a config.cache.  That brings configure
> to 140% of parallel compilation, but we're talking an overall build
> like 6 seconds.

That works when you repeatedly build the same package over and over
again with the exact same toolchain and environment.

My use case in Buildroot is very different: we build potentially
several dozens of different software components, each time with a
different toolchain/environment. So we're almost never rebuilding with
the exact same configuration, and therefore using a cache doesn't
really work for our use case.

Best regards,

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com