kbuild: unify two modpost invocations
Currently, modpost is executed twice; first for vmlinux, second
for modules.
This commit merges them.
Current build flow
==================
1) build obj-y and obj-m objects
2) link vmlinux.o
3) modpost for vmlinux
4) link vmlinux
5) modpost for modules
6) link modules (*.ko)
The build steps 1) through 6) are serialized, that is, modules are
built after vmlinux. You do not get benefits of parallel builds when
scripts/link-vmlinux.sh is being run.
New build flow
==============
1) build obj-y and obj-m objects
2) link vmlinux.o
3) modpost for vmlinux and modules
4a) link vmlinux
4b) link modules (*.ko)
In the new build flow, modpost is invoked just once.
vmlinux and modules are built in parallel. One exception is
CONFIG_DEBUG_INFO_BTF_MODULES=y, where modules depend on vmlinux.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
diff --git a/Makefile b/Makefile
index 21c41a0..41ab276 100644
--- a/Makefile
+++ b/Makefile
@@ -1150,7 +1150,7 @@
$(CONFIG_SHELL) $< "$(LD)" "$(KBUILD_LDFLAGS)" "$(LDFLAGS_vmlinux)"; \
$(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) $@, true)
-vmlinux: scripts/link-vmlinux.sh vmlinux.o $(KBUILD_LDS) FORCE
+vmlinux: scripts/link-vmlinux.sh vmlinux.o $(KBUILD_LDS) modpost FORCE
+$(call if_changed_dep,link-vmlinux)
targets := vmlinux
@@ -1426,7 +1426,13 @@
# Build modules
#
-modules: $(if $(KBUILD_BUILTIN),vmlinux) modules_prepare
+# *.ko are usually independent of vmlinux, but CONFIG_DEBUG_INFOBTF_MODULES
+# is an exception.
+ifdef CONFIG_DEBUG_INFO_BTF_MODULES
+modules: vmlinux
+endif
+
+modules: modules_prepare
# Target to prepare building external modules
modules_prepare: prepare
@@ -1739,8 +1745,12 @@
$(MODORDER): $(build-dir)
@:
-modules: modules_check
- $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost
+# KBUILD_MODPOST_NOFINAL can be set to skip the final link of modules.
+# This is solely useful to speed up test compiles.
+modules: modpost
+ifneq ($(KBUILD_MODPOST_NOFINAL),1)
+ $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modfinal
+endif
PHONY += modules_check
modules_check: $(MODORDER)
@@ -1771,6 +1781,11 @@
endif # CONFIG_MODULES
+PHONY += modpost
+modpost: $(if $(single-build),, $(if $(KBUILD_BUILTIN), vmlinux.o)) \
+ $(if $(KBUILD_MODULES), modules_check)
+ $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost
+
# Single targets
# ---------------------------------------------------------------------------
# To build individual files in subdirectories, you can do like this:
@@ -1790,16 +1805,19 @@
single-no-ko := $(filter-out $(single-ko), $(MAKECMDGOALS)) \
$(foreach x, o mod, $(patsubst %.ko, %.$x, $(single-ko)))
-$(single-ko): single_modpost
+$(single-ko): single_modules
@:
$(single-no-ko): $(build-dir)
@:
# Remove MODORDER when done because it is not the real one.
-PHONY += single_modpost
-single_modpost: $(single-no-ko) modules_prepare
+PHONY += single_modules
+single_modules: $(single-no-ko) modules_prepare
$(Q){ $(foreach m, $(single-ko), echo $(extmod_prefix)$m;) } > $(MODORDER)
$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost
+ifneq ($(KBUILD_MODPOST_NOFINAL),1)
+ $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modfinal
+endif
$(Q)rm -f $(MODORDER)
single-goals := $(addprefix $(build-dir)/, $(single-no-ko))
