kbuild: restore autoksyms.h touch 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
cause.
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 'scripts' as follows:
$(vmlinux-dirs): prepare scripts
Because there is no dependency between 'prepare' and 'scripts', the
parallel building can execute them simultaneously.
'prepare' depends on 'prepare1', which touched autoksyms.h, while
'scripts' descends into script/, then scripts/mod/, which needs
<generated/autoksyms.h> if CONFIG_TRIM_UNUSED_KSYMS. It was the
reason of the race.
I am not happy to have unrelated code in the Kconfig Makefile, so
getting it back to the top Makefile.
I removed the standalone test target because I want to use it to
create an empty autoksyms.h file. Here is a little improvement;
unnecessary autoksyms.h is not created when CONFIG_TRIM_UNUSED_KSYMS
is disabled.
[1] https://lkml.org/lkml/2016/11/30/734
[2] https://lkml.org/lkml/2016/11/30/531
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Nicolas Pitre <nico@linaro.org>
diff --git a/Makefile b/Makefile
index 5aa07da..b65cfe3 100644
--- a/Makefile
+++ b/Makefile
@@ -1019,9 +1019,11 @@
"$(MAKE) -f $(srctree)/Makefile vmlinux"
endif
-# standalone target for easier testing
-include/generated/autoksyms.h: FORCE
- $(Q)$(CONFIG_SHELL) $(srctree)/scripts/adjust_autoksyms.sh true
+autoksyms_h := $(if $(CONFIG_TRIM_UNUSED_KSYMS), include/generated/autoksyms.h)
+
+$(autoksyms_h):
+ $(Q)mkdir -p $(dir $@)
+ $(Q)touch $@
ARCH_POSTLINK := $(wildcard $(srctree)/arch/$(SRCARCH)/Makefile.postlink)
@@ -1065,7 +1067,7 @@
# in parallel
PHONY += scripts
scripts: scripts_basic include/config/auto.conf include/config/tristate.conf \
- asm-generic gcc-plugins
+ asm-generic gcc-plugins $(autoksyms_h)
$(Q)$(MAKE) $(build)=$(@)
# Things we need to do before we recursively start building the kernel
@@ -1095,7 +1097,7 @@
# 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 \
include/config/auto.conf
$(cmd_crmodverdir)