kbuild: generate autoksyms.h early
When doing a cold build, autoksyms.h starts empty, and is updated late
in the build process to have visibility over the symbols used by in-tree
drivers. But since the symbol whitelist is known upfront, it can be used
to pre-populate autoksyms.h and maximize the amount of code that can be
compiled to its final state in a single pass, hence reducing build time.
Do this by using gen_autoksyms.sh to initialize autoksyms.h instead of
creating an empty file.
Acked-by: Nicolas Pitre <nico@fluxnic.net>
Tested-by: Matthias Maennich <maennich@google.com>
Reviewed-by: Matthias Maennich <maennich@google.com>
Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
diff --git a/Makefile b/Makefile
index 5435d11..f8b70cf 100644
--- a/Makefile
+++ b/Makefile
@@ -1066,9 +1066,12 @@
autoksyms_h := $(if $(CONFIG_TRIM_UNUSED_KSYMS), include/generated/autoksyms.h)
+quiet_cmd_autoksyms_h = GEN $@
+ cmd_autoksyms_h = mkdir -p $(dir $@); \
+ $(CONFIG_SHELL) $(srctree)/scripts/gen_autoksyms.sh $@
+
$(autoksyms_h):
- $(Q)mkdir -p $(dir $@)
- $(Q)touch $@
+ $(call cmd,autoksyms_h)
ARCH_POSTLINK := $(wildcard $(srctree)/arch/$(SRCARCH)/Makefile.postlink)