Re: [PATCHv2][RFC] arch-armv7ve.inc: respect armv7a override as well

[Phil Blundell <pb@pbcl.net>]

On Mon, 2016-01-11 at 11:10 -0800, Khem Raj wrote:
> So I was asking was what improvements do we get if we choose armv7ve as tune
> and I did not get any definitive answers. 

If you compile with -march=armv7ve then you get the integer divide
instructions, which are not enabled under -march=armv7a.

>Why shouldnt we keep using armv7-a and tune the handful of apps to
>armv7ve where it is required.

That'd be a distro decision.  I agree that if you are targetting a mix
of cores, some that have hardware div and some that don't, it may not be
sensible to compile everything twice and you might want to standardise
on armv7a as the least common denominator.  But Cortex-A15 is
widespread, and I think people who select tune-cortexa15.inc would have
a reasonable expectation that it would, indeed, tune for the
instructions that their processor supports.  That's not to say that it
necessarily needs to be a generic armv7ve tune of course.

> We should strive to reduce this tuning mayhem
> on arm especially.

I agree with this, though.

p.