arch/arm: add option to use *eabihf tuples

Toolchains that use the hard-float ABI now are to be denoted by a tuple
ending in *eabihf, while the prevbious *eabi is now an indication that
the toolchain uses the softfloat ABI.

This is purely a cosmetic thing, for distros to differentiate their
hardfloat-ABI ports from their softfloat-ABI ports.

(note: softfloat ABI does not mean that it is using softfloats; it can
be using hardfloat instructions, but using the softfloat ABI).

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>

config/arch/arm.in.2

@@ -46,6 +46,37 @@ config ARCH_ARM_EABI
     help
       Set up the toolchain so that it generates EABI-compliant binaries.
 
+config ARCH_ARM_TUPLE_USE_EABIHF
+    bool
+    prompt "append 'hf' to the tuple (EXPERIMENTAL)"
+    depends on ARCH_FLOAT_HW
+    depends on ARCH_ARM_EABI    # Until we only support that...
+    depends on EXPERIMENTAL
+    help
+      Is you say 'y' here, then the tuple for the toolchain will end
+      up with *eabihf, instead of the usual *eabi.
+
+      *eabihf is used to denote that the toolchain *is* using the
+      hard-float ABI, while *eabi is just an indication of using the
+      soft-float ABI.
+
+      Ie. all one can say is:  *eabihf ⊢ hard-float ABI
+
+      Saying 'n' here does *not* impact the ability of the toolchain to
+      generate hard-float instructions with the hard-float ABI. It is a
+      purely cosmetic thing, used by distros to differentiate their
+      hard-float-ABI-using ports from their soft-float-ABI-using ports.
+      (eg. Debian Wheezy and above).
+
+      This is an option, as not all versions of gcc/binutils do support
+      such tuple, and fail to build with *eabihf. Stock gcc version up
+      to, and including 4.7.2 have an issue or another with *eabihf.
+
+      This option is here for the future.
+
+      Say 'n', unless you are trying to fix gcc to properly recognise
+      the *eabihf tuples.
+
 config ARCH_ARM_ABI_OK
     bool
     default y

scripts/build/arch/arm.sh

@@ -24,4 +24,8 @@ CT_DoArchTupleValues() {
     if [ "${CT_ARCH_ARM_INTERWORKING}" = "y" ]; then
         CT_ARCH_TARGET_CFLAGS+=" -mthumb-interwork"
     fi
+
+    if [ "${CT_ARCH_ARM_TUPLE_USE_EABIHF}" = "y" ]; then
+        CT_TARGET_SYS="${CT_TARGET_SYS}hf"
+    fi
 }