We need --with-cpu based to glibc to get proper support on 603e & e500mc
to pickup proper math libs to deal with sqrt.  These core do not
implement the fsqrt[s] instructions that the normal PPC math libs
utilize.

This causes use to not set AVAILTUNES specifically to the sub-arch only
as we arent generically compatiable.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

We need to ensure only one value ends up in TUNE_PKGARCH rather than several.
This change ensures consistency accross all the PPC tune files and that they
correctly inherit the core value but also allow it to be overwritten.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

Signed-off-by: Malcolm Crossley <malcolm.crossley@ge.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

These changes revolve around the idea of tune features. These are represented by
'flag' strings that are included in the TUNE_FEATURES variable.

Any string included in TUNE_FEATURES should also add a TUNEVALID[<name>] entry so
we can know which flags are available in TUNE_FEATURES and have documentation about
what the flags do. We will add sanity code to error if flags are listed in
TUNE_FEATURES but are not documented in TUNEVALID.

A given tune configuration will want to define one or more predetermined sets of
_FEATURE flag lists. These are defined in the form TUNE_FEATURES_tune-<name>.
For defined tune configuation, <name> should be added to the AVAILTUNE list so that
we can determine what tune configurations are available. Flags cannot be used in this
case as with TUNEVALID since its useful to be able to build up tune lists from other
TUNE_FEATURES_tune-yyy options.

A given tune configuration may also define PACKAGE_EXTRA_ARCHS_tune-<name> and
BASE_LIB_tune-<name> to control the multilib location. All options can be overridden
by the distro or local user configuration.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

Since we're updating the tune file format, it makes sense to abstract
the compiler tune arguments at this point too. This means that should
these need to be overridden at any point, the original values can
still be obtained in a similar manner to the other TUNE* variables.

Whilst this isn't strictly necessary for any current need, its likely
good practise to standardise this behaviour.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

There is currently consideradble confusion over how the tune files operate
and how these interact with the rest of the build system. This update/overhaul
changes things so the tune files are primarily resonsible for setting:

TUNE_ARCH - What was formerly set as TARGET_ARCH and is the value that
represents the architecture we're targetting.

TUNE_PKGARCH - The value that represents the tune confuration that this set
of tune parameters results in.

This allows the significant improvement that the core can now always determine
the target architecture value, even when TARGET_ARCH needs to be reset to
something different and likewise, there is one package architecture variable
the core can reference allowing simplification of the BASE_PACKAGE_ARCH, PACKAGE_ARCH
and FEED_ARCH variables.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>