conf/machine/include: Cleanup MIPS tunings to match README

Cleanup the MIPS tunings to match the new tuning README file.  Also
add a MIPS specific README file to explain the MIPS specifical
architectural issues.

Finally correct the variant configurations within the tune-mips32.inc.

(From OE-Core rev: efbfa2ace3362393a20340af93e8dcab17a8619a)

Signed-off-by: Mark Hatle <mark.hatle@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

1 files changed, 36 insertions, 0 deletions

diff --git a/meta/conf/machine/include/mips/README b/meta/conf/machine/include/mips/README
new file mode 100644
index 0000000000..c375f316df
--- /dev/null
+++ b/meta/conf/machine/include/mips/README
@@ -0,0 +1,36 @@
+2012/03/30 - Mark Hatle <mark.hatle@windriver.com>
+  - Initial Version
+
+MIPS currently defines 12 ABIs.  Combinations of:
+ *) Big/Little Endian
+ *) Hardware/Software Floating Point
+ *) o32, n32, n64 ABI
+
+TUNE_ARCH, the GNU canonical arch, is defined as:
+
+mips${MIPSPKGSFX_BYTE}${MIPSPKGSFX_ENDIAN}
+
+The package arch is defined in such a way to generated a standard naming
+scheme.  The scheme is: <mips variant>[-nf][-n32]
+
+TUNE_PKGARCH is defined as:
+
+${MIPSPKGSFX_VARIANT_tune-${DEFAULTTUNE}}${MIPSPKGSFX_FPU}${MIPSPKGSFX_ABI}
+
+The following is a list of MIPS specific variables:
+
+MIPSPKGSFX_BYTE - This is defined as either blank and "64" for MIPS64 CPUs.
+
+MIPSPKGSFX_ENDIAN - For bigendian hardware this is blank, otherwise it's
+defined as "el".
+
+MIPSPKGSFX_VARIANT_tune-<tune> - In the default tunings it is set to the
+same value as TUNE_ARCH.  In custom, optimized tunings, the value should
+be modified to more precisely describe the tuning.
+
+MIPSPKGSFX_FPU - The value is set to "" or "-nf", where "-nf" indicates 
+that the tune is using a non-floating point ABI.
+
+MIPSPKGSFX_ABI - This is used to specify an alternative ABI when the previous
+values are not enough to distringuish the package.  "-n32" is added when
+building for N32 ABI.