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authorMasahiro Yamada <masahiroy@kernel.org>2022-09-24 21:19:14 +0300
committerMasahiro Yamada <masahiroy@kernel.org>2022-10-02 12:04:05 +0300
commit3216484550610470013b7ce1c9ed272da0a74589 (patch)
treee24e7df02e90b7e798ae5aa67a5e4468142978c8 /Makefile
parent4b0986590062ce12c134c00cf32b9f9b846aeff5 (diff)
downloadlinux-3216484550610470013b7ce1c9ed272da0a74589.tar.xz
kbuild: use obj-y instead extra-y for objects placed at the head
The objects placed at the head of vmlinux need special treatments: - arch/$(SRCARCH)/Makefile adds them to head-y in order to place them before other archives in the linker command line. - arch/$(SRCARCH)/kernel/Makefile adds them to extra-y instead of obj-y to avoid them going into built-in.a. This commit gets rid of the latter. Create vmlinux.a to collect all the objects that are unconditionally linked to vmlinux. The objects listed in head-y are moved to the head of vmlinux.a by using 'ar m'. With this, arch/$(SRCARCH)/kernel/Makefile can consistently use obj-y for builtin objects. There is no *.o that is directly linked to vmlinux. Drop unneeded code in scripts/clang-tools/gen_compile_commands.py. $(AR) mPi needs 'T' to workaround the llvm-ar bug. The fix was suggested by Nathan Chancellor [1]. [1]: https://lore.kernel.org/llvm/YyjjT5gQ2hGMH0ni@dev-arch.thelio-3990X/ Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Tested-by: Nick Desaulniers <ndesaulniers@google.com> Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
Diffstat (limited to 'Makefile')
-rw-r--r--Makefile23
1 files changed, 18 insertions, 5 deletions
diff --git a/Makefile b/Makefile
index 22a956b9ffe4..8da45f76ec31 100644
--- a/Makefile
+++ b/Makefile
@@ -645,6 +645,8 @@ else
__all: modules
endif
+targets :=
+
# Decide whether to build built-in, modular, or both.
# Normally, just do built-in.
@@ -1107,7 +1109,7 @@ export ARCH_LIB := $(filter %/, $(libs-y))
export ARCH_DRIVERS := $(drivers-y) $(drivers-m)
# Externally visible symbols (used by link-vmlinux.sh)
-KBUILD_VMLINUX_OBJS := $(head-y) ./built-in.a
+KBUILD_VMLINUX_OBJS := ./built-in.a
ifdef CONFIG_MODULES
KBUILD_VMLINUX_OBJS += $(patsubst %/, %/lib.a, $(filter %/, $(libs-y)))
KBUILD_VMLINUX_LIBS := $(filter-out %/, $(libs-y))
@@ -1115,7 +1117,7 @@ else
KBUILD_VMLINUX_LIBS := $(patsubst %/,%/lib.a, $(libs-y))
endif
-export KBUILD_VMLINUX_OBJS KBUILD_VMLINUX_LIBS
+export KBUILD_VMLINUX_LIBS
export KBUILD_LDS := arch/$(SRCARCH)/kernel/vmlinux.lds
# Recurse until adjust_autoksyms.sh is satisfied
@@ -1140,7 +1142,18 @@ quiet_cmd_autoksyms_h = GEN $@
$(autoksyms_h):
$(call cmd,autoksyms_h)
-vmlinux.o: autoksyms_recursive $(KBUILD_VMLINUX_OBJS) $(KBUILD_VMLINUX_LIBS) FORCE
+# '$(AR) mPi' needs 'T' to workaround the bug of llvm-ar <= 14
+quiet_cmd_ar_vmlinux.a = AR $@
+ cmd_ar_vmlinux.a = \
+ rm -f $@; \
+ $(AR) cDPrST $@ $(KBUILD_VMLINUX_OBJS); \
+ $(AR) mPiT $$($(AR) t $@ | head -n1) $@ $(head-y)
+
+targets += vmlinux.a
+vmlinux.a: $(KBUILD_VMLINUX_OBJS) autoksyms_recursive FORCE
+ $(call if_changed,ar_vmlinux.a)
+
+vmlinux.o: vmlinux.a $(KBUILD_VMLINUX_LIBS) FORCE
$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.vmlinux_o
ARCH_POSTLINK := $(wildcard $(srctree)/arch/$(SRCARCH)/Makefile.postlink)
@@ -1153,7 +1166,7 @@ cmd_link-vmlinux = \
vmlinux: scripts/link-vmlinux.sh vmlinux.o $(KBUILD_LDS) modpost FORCE
+$(call if_changed_dep,link-vmlinux)
-targets := vmlinux
+targets += vmlinux
# The actual objects are generated when descending,
# make sure no implicit rule kicks in
@@ -1878,7 +1891,7 @@ quiet_cmd_gen_compile_commands = GEN $@
cmd_gen_compile_commands = $(PYTHON3) $< -a $(AR) -o $@ $(filter-out $<, $(real-prereqs))
$(extmod_prefix)compile_commands.json: scripts/clang-tools/gen_compile_commands.py \
- $(if $(KBUILD_EXTMOD),,$(KBUILD_VMLINUX_OBJS) $(KBUILD_VMLINUX_LIBS)) \
+ $(if $(KBUILD_EXTMOD),, vmlinux.a $(KBUILD_VMLINUX_LIBS)) \
$(if $(CONFIG_MODULES), $(MODORDER)) FORCE
$(call if_changed,gen_compile_commands)