Re: [PATCH 3/3] Add basic PowerPC core tune config

[Richard Purdie <richard.purdie@linuxfoundation.org>]

On Tue, 2011-07-26 at 22:23 -0500, Kumar Gala wrote:
> On Jul 26, 2011, at 5:52 PM, Richard Purdie wrote:
> 
> > On Tue, 2011-07-26 at 17:02 -0500, Kumar Gala wrote:
> >> On Jul 26, 2011, at 11:18 AM, Richard Purdie wrote:
> >> 
> >>>>> You're already found the way to pass configuration to *libc using values
> >>>>> in TARGET_FPU to pickup the right configuration.
> >>>>> 
> >>>>> Is there a use case we're missing?
> >>>> 
> >>>> Yes, for [e]glibc we have optimized libc functions for a given /
> >>>> specific PPC processor.  So we need someway to tell configure this.
> >>> 
> >>> I'd do this by looking for flags in TUNE_FEATURES as Mark has also
> >>> mentioned.
> >>> 
> >>> Cheers,
> >>> 
> >>> Richard
> >> 
> >> Are we thinking something like the following in e[glibc] recipes:
> >> 
> >> EXTRA_OECONF += "${@bb.utils.contains("TUNE_FEATURES", "ppce500mc", "-with-cpu=e500mc", "", d)}"
> > 
> > Could we glean this information from the TUNE_CCARGS variable and do
> > this automatically?
> 
> For PPC we'd have:
> 
> 405
> 440
> 464
> 476
> 603e
> e500
> e500mc
> e5500
> 970
> a2
> cell
> power4
> power5
> power5+
> power6
> power6x
> power7
> 
> There isn't always a clean mapping.  For example ppce500 & ppce500v2 would want --with-cpu=e500.  I believe ppc603e, ppce300c2 would want --with-cpu=603e.
> 
> If we want to just do it as a python function w/a mapping table we could easily handle it that way.

We could also put:

GLIBC_EXTRA_OECONF = "--with-cpu=e500"

in the machine config files. When multilib gets involved we'd have to
become a little cleverer with this but there are options there...

Cheers,

Richard