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kbuild: fix endless syncconfig in case arch Makefile sets CROSS_COMPILE
Commit21c54b7747("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:21c54b7747("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> Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>
This commit is contained in:
Masahiro Yamada
parent
c90fca951e
commit
315bab4e97
54
Makefile
54
Makefile
@ -442,8 +442,6 @@ export KBUILD_AFLAGS_MODULE KBUILD_CFLAGS_MODULE KBUILD_LDFLAGS_MODULE
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export KBUILD_AFLAGS_KERNEL KBUILD_CFLAGS_KERNEL
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export KBUILD_ARFLAGS
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export CC_VERSION_TEXT := $(shell $(CC) --version | head -n 1)
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# When compiling out-of-tree modules, put MODVERDIR in the module
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# tree rather than in the kernel tree. The kernel tree might
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# even be read-only.
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@ -514,6 +512,12 @@ ifeq ($(shell $(CONFIG_SHELL) $(srctree)/scripts/cc-can-link.sh $(CC)), y)
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export CC_CAN_LINK
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endif
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# The expansion should be delayed until arch/$(SRCARCH)/Makefile is included.
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# Some architectures define CROSS_COMPILE in arch/$(SRCARCH)/Makefile.
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# CC_VERSION_TEXT is referenced from Kconfig (so it needs export),
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# and from include/config/auto.conf.cmd to detect the compiler upgrade.
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CC_VERSION_TEXT = $(shell $(CC) --version | head -n 1)
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ifeq ($(config-targets),1)
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# ===========================================================================
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# *config targets only - make sure prerequisites are updated, and descend
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@ -523,7 +527,7 @@ ifeq ($(config-targets),1)
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# KBUILD_DEFCONFIG may point out an alternative default configuration
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# used for 'make defconfig'
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include arch/$(SRCARCH)/Makefile
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export KBUILD_DEFCONFIG KBUILD_KCONFIG
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export KBUILD_DEFCONFIG KBUILD_KCONFIG CC_VERSION_TEXT
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config: scripts_basic outputmakefile FORCE
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$(Q)$(MAKE) $(build)=scripts/kconfig $@
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@ -585,12 +589,32 @@ virt-y := virt/
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endif # KBUILD_EXTMOD
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ifeq ($(dot-config),1)
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# Read in config
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-include include/config/auto.conf
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endif
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# The all: target is the default when no target is given on the
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# command line.
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# This allow a user to issue only 'make' to build a kernel including modules
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# Defaults to vmlinux, but the arch makefile usually adds further targets
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all: vmlinux
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CFLAGS_GCOV := -fprofile-arcs -ftest-coverage \
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$(call cc-option,-fno-tree-loop-im) \
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$(call cc-disable-warning,maybe-uninitialized,)
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export CFLAGS_GCOV CFLAGS_KCOV
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# The arch Makefile can set ARCH_{CPP,A,C}FLAGS to override the default
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# values of the respective KBUILD_* variables
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ARCH_CPPFLAGS :=
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ARCH_AFLAGS :=
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ARCH_CFLAGS :=
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include arch/$(SRCARCH)/Makefile
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ifeq ($(dot-config),1)
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ifeq ($(KBUILD_EXTMOD),)
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# Read in dependencies to all Kconfig* files, make sure to run
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# oldconfig if changes are detected.
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# Read in dependencies to all Kconfig* files, make sure to run syncconfig if
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# changes are detected. This should be included after arch/$(SRCARCH)/Makefile
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# because some architectures define CROSS_COMPILE there.
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-include include/config/auto.conf.cmd
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# To avoid any implicit rule to kick in, define an empty command
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@ -622,24 +646,6 @@ else
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include/config/auto.conf: ;
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endif # $(dot-config)
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# The all: target is the default when no target is given on the
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# command line.
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# This allow a user to issue only 'make' to build a kernel including modules
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# Defaults to vmlinux, but the arch makefile usually adds further targets
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all: vmlinux
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CFLAGS_GCOV := -fprofile-arcs -ftest-coverage \
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$(call cc-option,-fno-tree-loop-im) \
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$(call cc-disable-warning,maybe-uninitialized,)
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export CFLAGS_GCOV CFLAGS_KCOV
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# The arch Makefile can set ARCH_{CPP,A,C}FLAGS to override the default
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# values of the respective KBUILD_* variables
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ARCH_CPPFLAGS :=
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ARCH_AFLAGS :=
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ARCH_CFLAGS :=
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include arch/$(SRCARCH)/Makefile
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KBUILD_CFLAGS += $(call cc-option,-fno-delete-null-pointer-checks,)
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KBUILD_CFLAGS += $(call cc-disable-warning,frame-address,)
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KBUILD_CFLAGS += $(call cc-disable-warning, format-truncation)
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