FROMLIST: 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.
Bug: 148277666
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>
Link: https://lore.kernel.org/lkml/20200218094139.78835-4-qperret@google.com
Change-Id: I98f3394b190f097390f980e5d4d57981f91b22a6
diff --git a/Makefile b/Makefile
index 2cde2b2..a2d4dac 100644
--- a/Makefile
+++ b/Makefile
@@ -1125,9 +1125,12 @@
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)