On Fri, Sep 18, 2009 at 12:49:30PM -0700, akpm@xxxxxxxxxxxxxxxxxxxx wrote:
> From: Roland McGrath <roland@xxxxxxxxxx>
>
> This adds CROSS_COMPILE as a kconfig string so you can store it in
> .config. Then you can use plain "make" in the configured kernel build
> directory to do the right cross compilation without setting the
> command-line or environment variable every time.
>
> With this, you can set up different build directories for different kernel
> configurations, whether native or cross-builds, and then use the simple:
>
> make -C /build/dir M=module-source-dir
>
> idiom to build modules for any given target kernel, indicating which one
> by nothing but the build directory chosen.
>
> I tried a version that defaults the string with env="CROSS_COMPILE" so
> that in a "make oldconfig" with CROSS_COMPILE in the environment you can
> just hit return to store the way you're building it. But the kconfig
> prompt for strings doesn't give you any way to say you want an empty
> string instead of the default, so I punted that.
>
> Signed-off-by: Roland McGrath <roland@xxxxxxxxxx>
> Cc: Sam Ravnborg <sam@xxxxxxxxxxxx>
> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
I had queued this patch (but for various reasons it had
not hit -next - sigh).
It does not save/restore SUBARCH - but that should
be doable too.
For my testing it works and we save both ARCH and CROSS_COMPILE.
Sam
commit 07d291e7ad3bff028e7a452e5c2ad66dfdeef146
Author: Sam Ravnborg <sam@xxxxxxxxxxxx>
Date: Mon Jul 20 11:49:54 2009 +0200
kbuild: save ARCH & CROSS_COMPILE when building a kernel
When building a kernel for a different architecture
kbuild requires the user always to specify ARCH and
CROSS_COMPILE on the command-line.
We use the asm symlink to detect if user forgets to
specify the correct ARCH value - but that symlink
is about to die. And we do now want to loose this check.
This patch save the settings of ARCH and CROSS_COMPILE
in a file named ".kbuild".
The settings are saved during "make *config" time
and always read.
If user try to change the settings we error out.
This works both for plain builds and for O=...
builds.
So now you can do:
$ mkdir sparc64
$ make O=sparc64 ARCH=sparc64 CROSS_COMPILE=sparc64-linux- defconfig
$ cd sparc64
$ make
Notice that you no longer need to tell kbuild
the settings of ARCH and CROSS_COMPILE when you type make
in the output directory.
Likewise for plain builds where you do not use O=...
Signed-off-by: Sam Ravnborg <sam@xxxxxxxxxxxx>
diff --git a/Makefile b/Makefile
index 305d005..d46f688 100644
--- a/Makefile
+++ b/Makefile
@@ -179,9 +179,36 @@ SUBARCH := $(shell uname -m | sed -e s/i.86/i386/ -e s/sun4u/sparc64/ \
# Alternatively CROSS_COMPILE can be set in the environment.
# Default value for CROSS_COMPILE is not to prefix executables
# Note: Some architectures assign CROSS_COMPILE in their arch/*/Makefile
+#
+# To force ARCH and CROSS_COMPILE settings include .kbuild
+# in the kernel tree - do not patch this file.
export KBUILD_BUILDHOST := $(SUBARCH)
-ARCH ?= $(SUBARCH)
-CROSS_COMPILE ?=
+
+# Kbuild save the ARCH and CROSS_COMPILE setting in .kbuild
+# Restore these settings and check that user did not specify
+# conflicting values.
+ifneq ($(wildcard .kbuild),)
+ -include .kbuild
+ ifneq ($(CROSS_COMPILE),)
+ ifneq ($(CROSS_COMPILE),$(KBUILD_CROSS_COMPILE))
+ $(error CROSS_COMPILE changed from \
+ "$(KBUILD_CROSS_COMPILE)" to \
+ to "$(CROSS_COMPILE)". \
+ Use "make mrproper" to fix it up)
+ endif
+ endif
+ ifneq ($(ARCH),)
+ ifneq ($(KBUILD_ARCH),$(ARCH))
+ $(error ARCH changed from \
+ "$(KBUILD_ARCH)" to "$(ARCH)". \
+ Use "make mrproper" to fix it up)
+ endif
+ endif
+ CROSS_COMPILE := $(KBUILD_CROSS_COMPILE)
+ ARCH := $(KBUILD_ARCH)
+else
+ ARCH ?= $(SUBARCH)
+endif
# Architecture as present in compile.h
UTS_MACHINE := $(ARCH)
@@ -446,6 +473,10 @@ ifeq ($(config-targets),1)
include $(srctree)/arch/$(SRCARCH)/Makefile
export KBUILD_DEFCONFIG KBUILD_KCONFIG
+# save ARCH & CROSS_COMPILE settings
+$(shell (echo KBUILD_ARCH := $(ARCH) && \
+ echo KBUILD_CROSS_COMPILE := $(CROSS_COMPILE)) > .kbuild)
+
config: scripts_basic outputmakefile FORCE
$(Q)mkdir -p include/linux include/config
$(Q)$(MAKE) $(build)=scripts/kconfig $@
@@ -1197,6 +1228,7 @@ CLEAN_FILES += vmlinux System.map \
# Directories & files removed with 'make mrproper'
MRPROPER_DIRS += include/config include2 usr/include include/generated
MRPROPER_FILES += .config .config.old include/asm .version .old_version \
+ .kbuild \
include/linux/autoconf.h include/linux/version.h \
include/linux/utsrelease.h \
include/linux/bounds.h include/asm*/asm-offsets.h \
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