kbuild: Make the toolchain variables easily overwritable

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.

Gbp-Pq: Topic debian
Gbp-Pq: Name kernelvariables.patch

diff --git a/Makefile b/Makefile
index 7b93bc850afbbebfb327da8087ad76c5e4fe2595..82fa8a8cf9ede1905dff6842dd34177795af2b34 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -314,39 +314,6 @@ SUBARCH := $(shell uname -m | sed -e s/i.86/x86/ -e s/x86_64/x86/ \
 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
-
 KCONFIG_CONFIG ?= .config
 export KCONFIG_CONFIG
 
@@ -395,6 +362,38 @@ CFLAGS_KERNEL      =
 AFLAGS_KERNEL  =
 LDFLAGS_vmlinux =
 
+-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 ($(ARCH),tilegx)
+       SRCARCH := tile
+endif
+
 # Use USERINCLUDE when you must reference the UAPI directories only.
 USERINCLUDE    := \
                -I$(srctree)/arch/$(SRCARCH)/include/uapi \