@@ -442,8 +442,6 @@ export KBUILD_AFLAGS_MODULE KBUILD_CFLAGS_MODULE KBUILD_LDFLAGS_MODULE
export KBUILD_AFLAGS_KERNEL KBUILD_CFLAGS_KERNEL
export KBUILD_ARFLAGS
-export CC_VERSION_TEXT := $(shell $(CC) --version | head -n 1)
-
# When compiling out-of-tree modules, put MODVERDIR in the module
# tree rather than in the kernel tree. The kernel tree might
# even be read-only.
@@ -514,6 +512,12 @@ ifeq ($(shell $(CONFIG_SHELL) $(srctree)/scripts/cc-can-link.sh $(CC)), y)
export CC_CAN_LINK
endif
+# The expansion should be delayed until arch/$(SRCARCH)/Makefile is included.
+# Some architectures define CROSS_COMPILE in arch/$(SRCARCH)/Makefile.
+# CC_VERSION_TEXT is referenced from Kconfig (so it needs export),
+# and from include/config/auto.conf.cmd to detect the compiler upgrade.
+CC_VERSION_TEXT = $(shell $(CC) --version | head -n 1)
+
ifeq ($(config-targets),1)
# ===========================================================================
# *config targets only - make sure prerequisites are updated, and descend
@@ -523,7 +527,7 @@ ifeq ($(config-targets),1)
# KBUILD_DEFCONFIG may point out an alternative default configuration
# used for 'make defconfig'
include arch/$(SRCARCH)/Makefile
-export KBUILD_DEFCONFIG KBUILD_KCONFIG
+export KBUILD_DEFCONFIG KBUILD_KCONFIG CC_VERSION_TEXT
config: scripts_basic outputmakefile FORCE
$(Q)$(MAKE) $(build)=scripts/kconfig $@
@@ -585,12 +589,32 @@ virt-y := virt/
endif # KBUILD_EXTMOD
ifeq ($(dot-config),1)
-# Read in config
-include include/config/auto.conf
+endif
+
+# The all: target is the default when no target is given on the
+# command line.
+# This allow a user to issue only 'make' to build a kernel including modules
+# Defaults to vmlinux, but the arch makefile usually adds further targets
+all: vmlinux
+
+CFLAGS_GCOV := -fprofile-arcs -ftest-coverage \
+ $(call cc-option,-fno-tree-loop-im) \
+ $(call cc-disable-warning,maybe-uninitialized,)
+export CFLAGS_GCOV CFLAGS_KCOV
+
+# The arch Makefile can set ARCH_{CPP,A,C}FLAGS to override the default
+# values of the respective KBUILD_* variables
+ARCH_CPPFLAGS :=
+ARCH_AFLAGS :=
+ARCH_CFLAGS :=
+include arch/$(SRCARCH)/Makefile
+ifeq ($(dot-config),1)
ifeq ($(KBUILD_EXTMOD),)
-# Read in dependencies to all Kconfig* files, make sure to run
-# oldconfig if changes are detected.
+# Read in dependencies to all Kconfig* files, make sure to run syncconfig if
+# changes are detected. This should be included after arch/$(SRCARCH)/Makefile
+# because some architectures define CROSS_COMPILE there.
-include include/config/auto.conf.cmd
# To avoid any implicit rule to kick in, define an empty command
@@ -622,24 +646,6 @@ else
include/config/auto.conf: ;
endif # $(dot-config)
-# The all: target is the default when no target is given on the
-# command line.
-# This allow a user to issue only 'make' to build a kernel including modules
-# Defaults to vmlinux, but the arch makefile usually adds further targets
-all: vmlinux
-
-CFLAGS_GCOV := -fprofile-arcs -ftest-coverage \
- $(call cc-option,-fno-tree-loop-im) \
- $(call cc-disable-warning,maybe-uninitialized,)
-export CFLAGS_GCOV CFLAGS_KCOV
-
-# The arch Makefile can set ARCH_{CPP,A,C}FLAGS to override the default
-# values of the respective KBUILD_* variables
-ARCH_CPPFLAGS :=
-ARCH_AFLAGS :=
-ARCH_CFLAGS :=
-include arch/$(SRCARCH)/Makefile
-
KBUILD_CFLAGS += $(call cc-option,-fno-delete-null-pointer-checks,)
KBUILD_CFLAGS += $(call cc-disable-warning,frame-address,)
KBUILD_CFLAGS += $(call cc-disable-warning, format-truncation)
Commit 21c54b774744 ("kconfig: show compiler version text in the top comment") was intended to detect the compiler upgrade, but Geert reported a breakage on the m68k build. The compiler upgrade is detected by the change of the environment variable, CC_VERSION_TEXT, which contains the first line of the output from $(CC) --version. Currently, this works well when CROSS_COMPILE is given via the environment variable or the Make command line. However, some architectures such as m68k can specify CROSS_COMPILE from arch/$(SRCARCH)/Makefile as well. In this case, "make ARCH=m68k" ends up with endless syncconfig loop. $ make ARCH=m68k defconfig *** Default configuration is based on 'multi_defconfig' # # configuration written to .config # $ make ARCH=m68k scripts/kconfig/conf --syncconfig Kconfig scripts/kconfig/conf --syncconfig Kconfig scripts/kconfig/conf --syncconfig Kconfig scripts/kconfig/conf --syncconfig Kconfig Things are happening like this: Because arch/$(SRCARCH)/Makefile is included after CC_VERSION_TEXT is set, it contains the host compiler version in the defconfig phase. To create or update auto.conf, the following line is triggered: include/config/%.conf: $(KCONFIG_CONFIG) include/config/auto.conf.cmd $(Q)$(MAKE) -f $(srctree)/Makefile syncconfig This recurses the top Makefile after arch/$(SRCARCH)/Makefile is included. CROSS_COMPILE is set to a m68k toolchain prefix and exported to the recursed Make. Then, syncconfig is invoked with the target compiler version in CC_VERSION_TEXT. The Make will restart because auto.conf and auto.conf.cmd have been updated. At this point, CROSS_COMPILE is reset, so CC_VERSION_TEXT is set to the host compiler version again. Then, syncconfig is triggered due to the change of CC_VERSION_TEXT. This loop continues eternally. To fix this problem, $(CC_VERSION_TEXT) must be evaluated only after arch/$(SRCARCH)/Makefile. Setting it earlier is OK as long as it is defined by using the '=' operator instead of ':='. For the defconfig phase, $(CC_VERSION_TEXT) is evaluated when Kbuild descends into scripts/kconfig/, so it contains the target compiler version correctly. include/config/auto.conf.cmd references $(CC_VERSION_TEXT) as well, so it must be included after arch/$(SRCARCH)/Makefile. Fixes: 21c54b774744 ("kconfig: show compiler version text in the top comment") Reported-by: Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> --- Makefile | 54 ++++++++++++++++++++++++++++++------------------------ 1 file changed, 30 insertions(+), 24 deletions(-)