From: Bastian Blank <waldi@debian.org>
Subject: kbuild: Make the toolchain variables easily overwritable
Date: Sun, 22 Feb 2009 15:39:35 +0100
Forwarded: not-needed

Allow make variables to be overridden for each flavour by a file in
the build tree, .kernelvariables.

We currently use this for ARCH, KERNELRELEASE, CC, and in some cases
also CROSS_COMPILE, CFLAGS_KERNEL and CFLAGS_MODULE.

This file can only be read after we establish the build tree, and all
use of $(ARCH) needs to be moved after this.

--- a/Makefile
+++ b/Makefile
@@ -195,42 +195,6 @@ export KBUILD_BUILDHOST := $(SUBARCH)
 ARCH		?= $(SUBARCH)
 CROSS_COMPILE	?= $(CONFIG_CROSS_COMPILE:"%"=%)
 
-# Architecture as present in compile.h
-UTS_MACHINE 	:= $(ARCH)
-SRCARCH 	:= $(ARCH)
-
-# Additional ARCH settings for x86
-ifeq ($(ARCH),i386)
-        SRCARCH := x86
-endif
-ifeq ($(ARCH),x86_64)
-        SRCARCH := x86
-endif
-
-# Additional ARCH settings for sparc
-ifeq ($(ARCH),sparc32)
-       SRCARCH := sparc
-endif
-ifeq ($(ARCH),sparc64)
-       SRCARCH := sparc
-endif
-
-# Additional ARCH settings for sh
-ifeq ($(ARCH),sh64)
-       SRCARCH := sh
-endif
-
-# Additional ARCH settings for tile
-ifeq ($(ARCH),tilepro)
-       SRCARCH := tile
-endif
-ifeq ($(ARCH),tilegx)
-       SRCARCH := tile
-endif
-
-# Where to locate arch specific headers
-hdr-arch  := $(SRCARCH)
-
 KCONFIG_CONFIG	?= .config
 export KCONFIG_CONFIG
 
@@ -349,6 +313,44 @@ CFLAGS_KERNEL	=
 AFLAGS_KERNEL	=
 CFLAGS_GCOV	= -fprofile-arcs -ftest-coverage
 
+-include $(obj)/.kernelvariables
+
+# Architecture as present in compile.h
+UTS_MACHINE 	:= $(ARCH)
+SRCARCH 	:= $(ARCH)
+
+# Additional ARCH settings for x86
+ifeq ($(ARCH),i386)
+        SRCARCH := x86
+endif
+ifeq ($(ARCH),x86_64)
+        SRCARCH := x86
+endif
+
+# Additional ARCH settings for sparc
+ifeq ($(ARCH),sparc64)
+       SRCARCH := sparc
+endif
+
+# Additional ARCH settings for sh
+ifeq ($(ARCH),sh64)
+       SRCARCH := sh
+endif
+
+# Additional ARCH settings for tile
+ifeq ($(ARCH),tilepro)
+       SRCARCH := tile
+endif
+ifeq ($(ARCH),tilegx)
+       SRCARCH := tile
+endif
+
+# Where to locate arch specific headers
+hdr-arch  := $(SRCARCH)
+
+ifeq ($(ARCH),m68knommu)
+       hdr-arch  := m68k
+endif
 
 # Use USERINCLUDE when you must reference the UAPI directories only.
 USERINCLUDE    := \