Re: ARM tunings was Re: [PATCH 3/7] conf/machine/include: Cleanup MIPS tunings to match README

[Phil Blundell <philb@gnu.org>]

On Tue, 2012-04-10 at 12:39 -0500, Mark Hatle wrote:
> The installation system uses a best 
> to least best match when doing assembly actions.  So if the part is an ARMv7a, 
> it will first look for ARMv7a w/ thumb, vfp and neon, not finding that, ARMv7a 
> w/ thumb and vfp, then ARMv7a w/ thumb, then ARMv5 w/ thumb and vfp, then ARMv5 
> w/ thumb, and finally fall back to the ARMv5 binaries.

This sounds like exactly the behaviour you would get with the current
ARM tunings (except the Thumb bit which, as previously discussed, I
think is somewhat misguided in the first place).  The existing ARM
tunings do seem to correctly encode VFP and Neon-ness.  

Which part isn't working for you?  Maybe you could give a concrete
example of where exactly it falls down.

> I can very much understand that in OE, for ARM specifically the package arch is 
> simply indicating basic compatibility and not ABI & ISA & Optimization like it 
> is on other architectures.

Well, I would consider "ABI & ISA" to be a fairly big part of "basic
compatibility".  It is true that we don't currently encode
optimisations, but as I previously mentioned I don't think many (perhaps
any) other distributions do that either, and it's perhaps debatable
whether it would be a very useful thing to do in the general case.  For
individual packages you can obviously force the issue in your DISTRO
configuration anyway.

p.