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Message-ID: <20071008200255.GA16497@uranus.ravnborg.org>
Date: Mon, 8 Oct 2007 22:02:55 +0200
From: Sam Ravnborg <sam@...nborg.org>
To: kbuild devel <kbuild-devel@...ts.sourceforge.net>,
LKML <linux-kernel@...r.kernel.org>
Subject: [RFC/RFT] kbuild: save ARCH & CROSS_COMPILE
One of the complaints that I continue to hear is that kbuild
is lacking a way to 'remember' the ARCH and CROSS_COMPILE
values originally used.
Likewise we have people that change ARCH settings and get
a lot of build errors due to asm symlink pointing at the
wrong directory.
This patch tries to address this by saving ARCH and
CROSS_COMPILE settings and error out if user specify
anohter ARCH or CROSS_COMPILE setting.
If there is inconsistency then error out and suggest
to run make mrproper.
This will as a side-effect prevent a build with the wrong
asm symlink.
The settings are stored in the build directory in a file
named "Kbuild.config" (should it be a .dot file?).
I have tested it here with success - but please give
it a try in your setup and let me know if anything breaks.
The patch is on top of latest linus tree but should apply
with some fuzz to -mm too (at least it apply on top of
my kbuild.git tree).
PS. I do not like adding additional cruft to the top-level
Makefile but did not find an easy way to push this to
kconfig.
Sam
diff --git a/Makefile b/Makefile
index 6fc97bf..9f6d03f 100644
--- a/Makefile
+++ b/Makefile
@@ -182,8 +182,33 @@ SUBARCH := $(shell uname -m | sed -e s/i.86/i386/ -e s/sun4u/sparc64/ \
# Default value for CROSS_COMPILE is not to prefix executables
# Note: Some architectures assign CROSS_COMPILE in their arch/*/Makefile
-ARCH ?= $(SUBARCH)
-CROSS_COMPILE ?=
+# Kbuild save the ARCH and CROSS_COMPILE setting in Kbuild.config
+# Restore these settings and check that user did not specify
+# conflicting values.
+Kbuild.config: ;
+noconfigcheck-targets := clean mrproper distclean help %config
+
+ifneq ($(wildcard Kbuild.config),)
+ -include Kbuild.config
+ ifeq ($(filter $(noconfigcheck-targets),$(MAKECMDGOALS)),)
+ ifneq ($(CROSS_COMPILE),)
+ ifneq ($(CROSS_COMPILE),$(KBUILD_CROSS_COMPILE))
+ $(error CROSS_COMPILE changed from "$(KBUILD_CROSS_COMPILE)" \
+ 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
+ endif
+ CROSS_COMPILE := $(KBUILD_CROSS_COMPILE)
+ ARCH := $(KBUILD_ARCH)
+else
+ ARCH ?= $(SUBARCH)
+endif
# Architecture as present in compile.h
UTS_MACHINE := $(ARCH)
@@ -351,6 +376,12 @@ scripts_basic:
# To avoid any implicit rule to kick in, define an empty command.
scripts/basic/%: scripts_basic ;
+# Save CROSS_COMPILE and ARCH for subsequent make invocations
+PHONY += Kbuild.config.save
+Kbuild.config.save:
+ $(Q)echo KBUILD_ARCH := $(ARCH) > Kbuild.config
+ $(Q)echo KBUILD_CROSS_COMPILE := $(CROSS_COMPILE) >> Kbuild.config
+
PHONY += outputmakefile
# outputmakefile generates a Makefile in the output directory, if using a
# separate output directory. This allows convenient use of make in the
@@ -413,7 +444,7 @@ ifeq ($(config-targets),1)
include $(srctree)/arch/$(ARCH)/Makefile
export KBUILD_DEFCONFIG
-config %config: scripts_basic outputmakefile FORCE
+config %config: scripts_basic outputmakefile Kbuild.config.save FORCE
$(Q)mkdir -p include/linux include/config
$(Q)$(MAKE) $(build)=scripts/kconfig $@
@@ -853,7 +884,10 @@ PHONY += prepare archprepare prepare0 prepare1 prepare2 prepare3
# and if so do:
# 1) Check that make has not been executed in the kernel src $(srctree)
# 2) Create the include2 directory, used for the second asm symlink
-prepare3: include/config/kernel.release
+prepare3: include/config/kernel.release Kbuild.config.save
+ifneq ($(KBUILD_CROSS_COMPILE)$(KBUILD_ARCH),)
+ $(Q)echo ' Using ARCH=$(ARCH) CROSS_COMPILE=$(CROSS_COMPILE)'
+endif
ifneq ($(KBUILD_SRC),)
@echo ' Using $(srctree) as source for kernel'
$(Q)if [ -f $(srctree)/.config -o -d $(srctree)/include/config ]; then \
@@ -919,10 +953,10 @@ define filechk_version.h
echo '#define KERNEL_VERSION(a,b,c) (((a) << 16) + ((b) << 8) + (c))';)
endef
-include/linux/version.h: $(srctree)/Makefile FORCE
+include/linux/version.h: $(srctree)/Makefile prepare2 FORCE
$(call filechk,version.h)
-include/linux/utsrelease.h: include/config/kernel.release FORCE
+include/linux/utsrelease.h: include/config/kernel.release prepare2 FORCE
$(call filechk,utsrelease.h)
# ---------------------------------------------------------------------------
@@ -1050,7 +1084,7 @@ CLEAN_FILES += vmlinux System.map \
MRPROPER_DIRS += include/config include2 usr/include
MRPROPER_FILES += .config .config.old include/asm .version .old_version \
include/linux/autoconf.h include/linux/version.h \
- include/linux/utsrelease.h \
+ include/linux/utsrelease.h Kbuild.config \
Module.symvers tags TAGS cscope*
# clean - Delete most, but leave enough to build external modules
-
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