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Subject[PATCH 4/7] kbuild: restore touching autoksyms.h to the top Makefile
Commit d3fc425e819b ("kbuild: make sure autoksyms.h exists early")
moved the code that touches autoksyms.h to scripts/kconfig/Makefile
with obscure reason.

From Nicolas' comment [1], he did not seem to be sure about the root

I guess I figured it out, so here is a fix-up I think is more correct.
According to the error log in the original post [2], the build failed
in scripts/mod/devicetable-offsets.c

scripts/mod/Makefile is descended from scripts/Makefile, which is
invoked from the top-level Makefile by the 'scripts' target.

To build vmlinux and/or modules, Kbuild descend into $(vmlinux-dirs).
This depends on 'prepare' and 'script' as follows:

$(vmlinux-dirs): prepare scripts

Because there is no dependency between 'prepare' and 'scripts', the
parallel building can run them simultaneously.

'prepare' depends on 'prepare1', which touched autoksyms.h, whereas
'scripts' descends into script/, then scripts/mod/, which needed
<generated/autoksyms.h> if CONFIG_TRIM_UNUSED_KSYMS. This was the
reason of race.

I am not happy to have unrelated code in the Kconfig Makefile, so
getting it back to the top Makefile.

I remove the standalone test target because I want to use it to
create an empty autoksyms.h file. Here is a little improvement;
unnecessary autoksyms.h is not created when CONFIG_TRIM_UNUSED_KSYMS
is disabled.


Signed-off-by: Masahiro Yamada <>

The discussion happened in Nov. 2016.

I was not involved in it.
I was not the Kbuild maintainer at that time.



Makefile | 12 +++++++-----
scripts/kconfig/Makefile | 2 --
2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/Makefile b/Makefile
index fab0e19..decc870 100644
--- a/Makefile
+++ b/Makefile
@@ -1010,9 +1010,11 @@ ifdef CONFIG_TRIM_UNUSED_KSYMS
"$(MAKE) -f $(srctree)/Makefile vmlinux"

-# standalone target for easier testing
-include/generated/autoksyms.h: FORCE
- $(Q)$(CONFIG_SHELL) $(srctree)/scripts/ true
+autoksyms_h := $(if $(CONFIG_TRIM_UNUSED_KSYMS), include/generated/autoksyms.h)
+ $(Q)mkdir -p $(dir $@)
+ $(Q)touch $@

ARCH_POSTLINK := $(wildcard $(srctree)/arch/$(SRCARCH)/Makefile.postlink)

@@ -1056,7 +1058,7 @@ include/config/kernel.release: include/config/auto.conf FORCE
# in parallel
PHONY += scripts
scripts: scripts_basic include/config/auto.conf include/config/tristate.conf \
- asm-generic gcc-plugins autoksyms
+ asm-generic gcc-plugins $(autoksyms_h)
$(Q)$(MAKE) $(build)=$(@)

# Things we need to do before we recursively start building the kernel
@@ -1086,7 +1088,7 @@ endif
# that need to depend on updated CONFIG_* values can be checked here.
prepare2: prepare3 prepare-compiler-check outputmakefile asm-generic

-prepare1: prepare2 $(version_h) include/generated/utsrelease.h \
+prepare1: prepare2 $(version_h) $(autoksyms_h) include/generated/utsrelease.h \

diff --git a/scripts/kconfig/Makefile b/scripts/kconfig/Makefile
index cb3ec53..eb139a1 100644
--- a/scripts/kconfig/Makefile
+++ b/scripts/kconfig/Makefile
@@ -38,8 +38,6 @@ nconfig: $(obj)/nconf
# for external use.
silentoldconfig: $(obj)/conf
$(Q)mkdir -p include/config include/generated
- $(Q)test -e include/generated/autoksyms.h || \
- touch include/generated/autoksyms.h
$< $(silent) --$@ $(Kconfig)

localyesconfig localmodconfig: $(obj)/ $(obj)/conf
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