kbuild: rename built-in.o to built-in.a

npiggin · kardebayan · commit cfa0ab379323 · 2026-02-13T09:31:59.000Z
Incremental linking is gone, so rename built-in.o to built-in.a, which
is the usual extension for archive files.

This patch does two things, first is a simple search/replace:

git grep -l 'built-in\.o' | xargs sed -i 's/built-in\.o/built-in\.a/g'

The second is to invert nesting of nested text manipulations to avoid
filtering built-in.a out from libs-y2:

-libs-y2 := $(filter-out %.a, $(patsubst %/, %/built-in.a, $(libs-y)))
+libs-y2 := $(patsubst %/, %/built-in.a, $(filter-out %.a, $(libs-y)))

Signed-off-by: Nicholas Piggin &lt;npiggin@gmail.com&gt;
Signed-off-by: Masahiro Yamada &lt;yamada.masahiro@socionext.com&gt;
diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt
@@ -153,12 +153,12 @@ more details, with real examples.
 	configuration.
 
 	Kbuild compiles all the $(obj-y) files.  It then calls
-	"$(LD) -r" to merge these files into one built-in.o file.
-	built-in.o is later linked into vmlinux by the parent Makefile.
+	"$(LD) -r" to merge these files into one built-in.a file.
+	built-in.a is later linked into vmlinux by the parent Makefile.
 
 	The order of files in $(obj-y) is significant.  Duplicates in
 	the lists are allowed: the first instance will be linked into
-	built-in.o and succeeding instances will be ignored.
+	built-in.a and succeeding instances will be ignored.
 
 	Link order is significant, because certain functions
 	(module_init() / __initcall) will be called during boot in the
@@ -222,7 +222,7 @@ more details, with real examples.
 	Note: Of course, when you are building objects into the kernel,
 	the syntax above will also work. So, if you have CONFIG_EXT2_FS=y,
 	kbuild will build an ext2.o file for you out of the individual
-	parts and then link this into built-in.o, as you would expect.
+	parts and then link this into built-in.a, as you would expect.
 
 --- 3.4 Objects which export symbols
 
@@ -232,7 +232,7 @@ more details, with real examples.
 --- 3.5 Library file goals - lib-y
 
 	Objects listed with obj-* are used for modules, or
-	combined in a built-in.o for that specific directory.
+	combined in a built-in.a for that specific directory.
 	There is also the possibility to list objects that will
 	be included in a library, lib.a.
 	All objects listed with lib-y are combined in a single
@@ -244,7 +244,7 @@ more details, with real examples.
 
 	Note that the same kbuild makefile may list files to be built-in
 	and to be part of a library. Therefore the same directory
-	may contain both a built-in.o and a lib.a file.
+	may contain both a built-in.a and a lib.a file.
 
 	Example:
 		#arch/x86/lib/Makefile
@@ -986,7 +986,7 @@ When kbuild executes, the following steps are followed (roughly):
 
 	$(head-y) lists objects to be linked first in vmlinux.
 	$(libs-y) lists directories where a lib.a archive can be located.
-	The rest list directories where a built-in.o object file can be
+	The rest list directories where a built-in.a object file can be
 	located.
 
 	$(init-y) objects will be located after $(head-y).
@@ -1071,7 +1071,7 @@ When kbuild executes, the following steps are followed (roughly):
 		extra-y := head.o init_task.o
 
 	In this example, extra-y is used to list object files that
-	shall be built, but shall not be linked as part of built-in.o.
+	shall be built, but shall not be linked as part of built-in.a.
 
 
 --- 6.7 Commands useful for building a boot image
diff --git a/Documentation/process/changes.rst b/Documentation/process/changes.rst
@@ -76,7 +76,7 @@ Binutils
 --------
 
 The build system has, as of 4.13, switched to using thin archives (`ar T`)
-rather than incremental linking (`ld -r`) for built-in.o intermediate steps.
+rather than incremental linking (`ld -r`) for built-in.a intermediate steps.
 This requires binutils 2.20 or newer.
 
 Perl
diff --git a/Makefile b/Makefile
@@ -35,7 +35,7 @@ unexport GREP_OPTIONS
 # Most importantly: sub-Makefiles should only ever modify files in
 # their own directory. If in some directory we have a dependency on
 # a file in another dir (which doesn't happen often, but it's often
-# unavoidable when linking the built-in.o targets which finally
+# unavoidable when linking the built-in.a targets which finally
 # turn into vmlinux), we will call a sub make in that other dir, and
 # after that we are sure that everything which is in that other dir
 # is now up to date.
@@ -1228,13 +1228,13 @@ vmlinux-dirs	:= $(patsubst %/,%,$(filter %/, $(init-y) $(init-m) \
 vmlinux-alldirs	:= $(sort $(vmlinux-dirs) $(patsubst %/,%,$(filter %/, \
 		     $(init-) $(core-) $(drivers-) $(net-) $(libs-) $(virt-))))
 
-init-y		:= $(patsubst %/, %/built-in.o, $(init-y))
-core-y		:= $(patsubst %/, %/built-in.o, $(core-y))
-drivers-y	:= $(patsubst %/, %/built-in.o, $(drivers-y))
-net-y		:= $(patsubst %/, %/built-in.o, $(net-y))
+init-y		:= $(patsubst %/, %/built-in.a, $(init-y))
+core-y		:= $(patsubst %/, %/built-in.a, $(core-y))
+drivers-y	:= $(patsubst %/, %/built-in.a, $(drivers-y))
+net-y		:= $(patsubst %/, %/built-in.a, $(net-y))
 libs-y1		:= $(patsubst %/, %/lib.a, $(libs-y))
-libs-y2		:= $(filter-out %.a, $(patsubst %/, %/built-in.o, $(libs-y)))
-virt-y		:= $(patsubst %/, %/built-in.o, $(virt-y))
+libs-y2		:= $(patsubst %/, %/built-in.a, $(filter-out %.a, $(libs-y)))
+virt-y		:= $(patsubst %/, %/built-in.a, $(virt-y))
 
 # Externally visible symbols (used by link-vmlinux.sh)
 export KBUILD_VMLINUX_INIT := $(head-y) $(init-y)
diff --git a/arch/Kconfig b/arch/Kconfig
@@ -611,7 +611,7 @@ config THIN_ARCHIVES
 	def_bool y
 	help
 	  Select this if the architecture wants to use thin archives
-	  instead of ld -r to create the built-in.o files.
+	  instead of ld -r to create the built-in.a files.
 
 config LTO
 	def_bool n
diff --git a/arch/blackfin/kernel/bfin_ksyms.c b/arch/blackfin/kernel/bfin_ksyms.c
@@ -36,7 +36,7 @@ EXPORT_SYMBOL(memchr);
 /*
  * Because string functions are both inline and exported functions and
  * folder arch/blackfin/lib is configured as a library path in Makefile,
- * symbols exported in folder lib  is not linked into built-in.o but
+ * symbols exported in folder lib  is not linked into built-in.a but
  * inlined only. In order to export string symbols to kernel module
  * properly, they should be exported here.
  */
diff --git a/arch/mips/boot/dts/brcm/Makefile b/arch/mips/boot/dts/brcm/Makefile
@@ -36,7 +36,7 @@ dtb-$(CONFIG_DT_NONE) += \
 
 obj-y				+= $(patsubst %.dtb, %.dtb.o, $(dtb-y))
 
-# Force kbuild to make empty built-in.o if necessary
+# Force kbuild to make empty built-in.a if necessary
 obj-				+= dummy.o
 
 always				:= $(dtb-y)
diff --git a/arch/mips/boot/dts/cavium-octeon/Makefile b/arch/mips/boot/dts/cavium-octeon/Makefile
@@ -3,7 +3,7 @@ dtb-$(CONFIG_CAVIUM_OCTEON_SOC)	+= octeon_3xxx.dtb octeon_68xx.dtb
 
 obj-y				+= $(patsubst %.dtb, %.dtb.o, $(dtb-y))
 
-# Force kbuild to make empty built-in.o if necessary
+# Force kbuild to make empty built-in.a if necessary
 obj-				+= dummy.o
 
 always				:= $(dtb-y)
diff --git a/arch/mips/boot/dts/img/Makefile b/arch/mips/boot/dts/img/Makefile
@@ -4,7 +4,7 @@ dtb-$(CONFIG_FIT_IMAGE_FDT_BOSTON)	+= boston.dtb
 dtb-$(CONFIG_MACH_PISTACHIO)	+= pistachio_marduk.dtb
 obj-$(CONFIG_MACH_PISTACHIO)	+= pistachio_marduk.dtb.o
 
-# Force kbuild to make empty built-in.o if necessary
+# Force kbuild to make empty built-in.a if necessary
 obj-				+= dummy.o
 
 always				:= $(dtb-y)
diff --git a/arch/mips/boot/dts/ingenic/Makefile b/arch/mips/boot/dts/ingenic/Makefile
@@ -4,7 +4,7 @@ dtb-$(CONFIG_JZ4780_CI20)	+= ci20.dtb
 
 obj-y				+= $(patsubst %.dtb, %.dtb.o, $(dtb-y))
 
-# Force kbuild to make empty built-in.o if necessary
+# Force kbuild to make empty built-in.a if necessary
 obj-				+= dummy.o
 
 always				:= $(dtb-y)
diff --git a/arch/mips/boot/dts/lantiq/Makefile b/arch/mips/boot/dts/lantiq/Makefile
@@ -3,7 +3,7 @@ dtb-$(CONFIG_DT_EASY50712)	+= easy50712.dtb
 
 obj-y				+= $(patsubst %.dtb, %.dtb.o, $(dtb-y))
 
-# Force kbuild to make empty built-in.o if necessary
+# Force kbuild to make empty built-in.a if necessary
 obj-				+= dummy.o
 
 always				:= $(dtb-y)
diff --git a/arch/mips/boot/dts/mti/Makefile b/arch/mips/boot/dts/mti/Makefile
@@ -4,7 +4,7 @@ dtb-$(CONFIG_LEGACY_BOARD_SEAD3)	+= sead3.dtb
 
 obj-y				+= $(patsubst %.dtb, %.dtb.o, $(dtb-y))
 
-# Force kbuild to make empty built-in.o if necessary
+# Force kbuild to make empty built-in.a if necessary
 obj-				+= dummy.o
 
 always				:= $(dtb-y)
diff --git a/arch/mips/boot/dts/netlogic/Makefile b/arch/mips/boot/dts/netlogic/Makefile
@@ -7,7 +7,7 @@ dtb-$(CONFIG_DT_XLP_RVP)	+= xlp_rvp.dtb
 
 obj-y				+= $(patsubst %.dtb, %.dtb.o, $(dtb-y))
 
-# Force kbuild to make empty built-in.o if necessary
+# Force kbuild to make empty built-in.a if necessary
 obj-				+= dummy.o
 
 always				:= $(dtb-y)
diff --git a/arch/mips/boot/dts/ni/Makefile b/arch/mips/boot/dts/ni/Makefile
@@ -1,6 +1,6 @@
 dtb-$(CONFIG_FIT_IMAGE_FDT_NI169445)	+= 169445.dtb
 
-# Force kbuild to make empty built-in.o if necessary
+# Force kbuild to make empty built-in.a if necessary
 obj-					+= dummy.o
 
 always					:= $(dtb-y)
diff --git a/arch/mips/boot/dts/pic32/Makefile b/arch/mips/boot/dts/pic32/Makefile
@@ -6,7 +6,7 @@ dtb-$(CONFIG_DTB_PIC32_NONE)		+= \
 
 obj-y				+= $(patsubst %.dtb, %.dtb.o, $(dtb-y))
 
-# Force kbuild to make empty built-in.o if necessary
+# Force kbuild to make empty built-in.a if necessary
 obj-				+= dummy.o
 
 always				:= $(dtb-y)
diff --git a/arch/mips/boot/dts/qca/Makefile b/arch/mips/boot/dts/qca/Makefile
@@ -6,7 +6,7 @@ dtb-$(CONFIG_ATH79)			+= ar9331_dragino_ms14.dtb
 dtb-$(CONFIG_ATH79)			+= ar9331_omega.dtb
 dtb-$(CONFIG_ATH79)			+= ar9331_tl_mr3020.dtb
 
-# Force kbuild to make empty built-in.o if necessary
+# Force kbuild to make empty built-in.a if necessary
 obj-				+= dummy.o
 
 always				:= $(dtb-y)
diff --git a/arch/mips/boot/dts/ralink/Makefile b/arch/mips/boot/dts/ralink/Makefile
@@ -8,7 +8,7 @@ dtb-$(CONFIG_DTB_VOCORE2)	+= vocore2.dtb
 
 obj-y				+= $(patsubst %.dtb, %.dtb.o, $(dtb-y))
 
-# Force kbuild to make empty built-in.o if necessary
+# Force kbuild to make empty built-in.a if necessary
 obj-				+= dummy.o
 
 always				:= $(dtb-y)
diff --git a/arch/mips/boot/dts/xilfpga/Makefile b/arch/mips/boot/dts/xilfpga/Makefile
@@ -3,7 +3,7 @@ dtb-$(CONFIG_XILFPGA_NEXYS4DDR)	+= nexys4ddr.dtb
 
 obj-y				+= $(patsubst %.dtb, %.dtb.o, $(dtb-y))
 
-# Force kbuild to make empty built-in.o if necessary
+# Force kbuild to make empty built-in.a if necessary
 obj-				+= dummy.o
 
 always				:= $(dtb-y)
diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
@@ -167,7 +167,7 @@ systbl_chk: $(src)/systbl_chk.sh $(obj)/systbl_chk.i
 	$(call cmd,systbl_chk)
 
 ifeq ($(CONFIG_PPC_OF_BOOT_TRAMPOLINE),y)
-$(obj)/built-in.o:		prom_init_check
+$(obj)/built-in.a:		prom_init_check
 
 quiet_cmd_prom_init_check = CALL    $<
       cmd_prom_init_check = $(CONFIG_SHELL) $< "$(NM)" "$(obj)/prom_init.o"
diff --git a/drivers/s390/Makefile b/drivers/s390/Makefile
@@ -4,5 +4,5 @@
 
 obj-y += cio/ block/ char/ crypto/ net/ scsi/ virtio/
 
-drivers-y += drivers/s390/built-in.o
+drivers-y += drivers/s390/built-in.a
 
diff --git a/firmware/Makefile b/firmware/Makefile
@@ -59,6 +59,6 @@ endif
 
 targets := $(patsubst $(obj)/%,%, \
                                 $(shell find $(obj) -name \*.gen.S 2>/dev/null))
-# Without this, built-in.o won't be created when it's empty, and the
+# Without this, built-in.a won't be created when it's empty, and the
 # final vmlinux link will fail.
 obj- := dummy
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
@@ -332,11 +332,11 @@ config DEBUG_SECTION_MISMATCH
 	    the analysis would not catch the illegal reference.
 	    This option tells gcc to inline less (but it does result in
 	    a larger kernel).
-	  - Run the section mismatch analysis for each module/built-in.o file.
+	  - Run the section mismatch analysis for each module/built-in.a file.
 	    When we run the section mismatch analysis on vmlinux.o, we
 	    lose valuable information about where the mismatch was
 	    introduced.
-	    Running the analysis for each module/built-in.o file
+	    Running the analysis for each module/built-in.a file
 	    tells where the mismatch happens much closer to the
 	    source. The drawback is that the same mismatch is
 	    reported at least twice.
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
@@ -86,7 +86,7 @@ obj-y += $(obj)/lib-ksyms.o
 endif
 
 ifneq ($(strip $(obj-y) $(obj-m) $(obj-) $(subdir-m) $(lib-target)),)
-builtin-target := $(obj)/built-in.o
+builtin-target := $(obj)/built-in.a
 endif
 
 modorder-target := $(obj)/modules.order
@@ -109,7 +109,7 @@ ifneq ($(KBUILD_CHECKSRC),0)
   endif
 endif
 
-# Do section mismatch analysis for each module/built-in.o
+# Do section mismatch analysis for each module/built-in.a
 ifdef CONFIG_DEBUG_SECTION_MISMATCH
   cmd_secanalysis = ; scripts/mod/modpost $@
 endif
@@ -524,7 +524,7 @@ else
   quiet_cmd_link_o_target = LD      $@
 endif
 
-# If the list of objects to link is empty, just create an empty built-in.o
+# If the list of objects to link is empty, just create an empty built-in.a
 cmd_link_o_target = $(if $(strip $(obj-y)),\
 		      $(cmd_make_builtin) $@ $(filter $(obj-y), $^) \
 		      $(cmd_secanalysis),\
diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
@@ -26,7 +26,7 @@ lib-y := $(filter-out $(obj-y), $(sort $(lib-y) $(lib-m)))
 
 # Handle objects in subdirs
 # ---------------------------------------------------------------------------
-# o if we encounter foo/ in $(obj-y), replace it by foo/built-in.o
+# o if we encounter foo/ in $(obj-y), replace it by foo/built-in.a
 #   and add the directory to the list of dirs to descend into: $(subdir-y)
 # o if we encounter foo/ in $(obj-m), remove it from $(obj-m)
 #   and add the directory to the list of dirs to descend into: $(subdir-m)
@@ -40,7 +40,7 @@ __subdir-y	:= $(patsubst %/,%,$(filter %/, $(obj-y)))
 subdir-y	+= $(__subdir-y)
 __subdir-m	:= $(patsubst %/,%,$(filter %/, $(obj-m)))
 subdir-m	+= $(__subdir-m)
-obj-y		:= $(patsubst %/, %/built-in.o, $(obj-y))
+obj-y		:= $(patsubst %/, %/built-in.a, $(obj-y))
 obj-m		:= $(filter-out %/, $(obj-m))
 
 # Subdirectories we need to descend into
@@ -61,7 +61,7 @@ multi-objs   := $(multi-objs-y) $(multi-objs-m)
 
 # $(subdir-obj-y) is the list of objects in $(obj-y) which uses dir/ to
 # tell kbuild to descend
-subdir-obj-y := $(filter %/built-in.o, $(obj-y))
+subdir-obj-y := $(filter %/built-in.a, $(obj-y))
 
 # $(obj-dirs) is a list of directories that contain object files
 obj-dirs := $(dir $(multi-objs) $(obj-y))
diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
@@ -4,7 +4,7 @@
 # link vmlinux
 #
 # vmlinux is linked from the objects selected by $(KBUILD_VMLINUX_INIT) and
-# $(KBUILD_VMLINUX_MAIN) and $(KBUILD_VMLINUX_LIBS). Most are built-in.o files
+# $(KBUILD_VMLINUX_MAIN) and $(KBUILD_VMLINUX_LIBS). Most are built-in.a files
 # from top-level directories in the kernel tree, others are specified in
 # arch/$(ARCH)/Makefile. Ordering when linking is important, and
 # $(KBUILD_VMLINUX_INIT) must be first. $(KBUILD_VMLINUX_LIBS) are archives
@@ -18,7 +18,7 @@
 #   |   +--< init/version.o + more
 #   |
 #   +--< $(KBUILD_VMLINUX_MAIN)
-#   |    +--< drivers/built-in.o mm/built-in.o + more
+#   |    +--< drivers/built-in.a mm/built-in.a + more
 #   |
 #   +--< $(KBUILD_VMLINUX_LIBS)
 #   |    +--< lib/lib.a + more
@@ -51,21 +51,21 @@ info()
 #
 # Traditional incremental style of link does not require this step
 #
-# built-in.o output file
+# built-in.a output file
 #
 archive_builtin()
 {
 	if [ -n "${CONFIG_THIN_ARCHIVES}" ]; then
-		info AR built-in.o
-		rm -f built-in.o;
-		${AR} rcsTP${KBUILD_ARFLAGS} built-in.o			\
+		info AR built-in.a
+		rm -f built-in.a;
+		${AR} rcsTP${KBUILD_ARFLAGS} built-in.a			\
 					${KBUILD_VMLINUX_INIT}		\
 					${KBUILD_VMLINUX_MAIN}
 
 		if [ -n "${CONFIG_LTO_CLANG}" ]; then
-			mv -f built-in.o built-in.o.tmp
-			${LLVM_AR} rcsT${KBUILD_ARFLAGS} built-in.o $(${AR} t built-in.o.tmp)
-			rm -f built-in.o.tmp
+			mv -f built-in.a built-in.a.tmp
+			${LLVM_AR} rcsT${KBUILD_ARFLAGS} built-in.a $(${AR} t built-in.a.tmp)
+			rm -f built-in.a.tmp
 		fi
 	fi
 }
@@ -104,7 +104,7 @@ modpost_link()
 
 	if [ -n "${CONFIG_THIN_ARCHIVES}" ]; then
 		objects="--whole-archive				\
-			built-in.o					\
+			built-in.a					\
 			--no-whole-archive				\
 			--start-group					\
 			${KBUILD_VMLINUX_LIBS}				\
@@ -160,7 +160,7 @@ vmlinux_link()
 
 		if [[ -n "${CONFIG_THIN_ARCHIVES}" && -z "${CONFIG_LTO_CLANG}" ]]; then
 			objects="--whole-archive 			\
-				built-in.o				\
+				built-in.a				\
 				--no-whole-archive			\
 				--start-group				\
 				${KBUILD_VMLINUX_LIBS}			\
@@ -179,7 +179,7 @@ vmlinux_link()
 	else
 		if [ -n "${CONFIG_THIN_ARCHIVES}" ]; then
 			objects="-Wl,--whole-archive			\
-				built-in.o				\
+				built-in.a				\
 				-Wl,--no-whole-archive			\
 				-Wl,--start-group			\
 				${KBUILD_VMLINUX_LIBS}			\
@@ -289,7 +289,7 @@ cleanup()
 	rm -f .tmp_version
 	rm -f .tmp_lto.lds
 	rm -f .tmp_vmlinux*
-	rm -f built-in.o
+	rm -f built-in.a
 	rm -f System.map
 	rm -f vmlinux
 	rm -f vmlinux.o
diff --git a/scripts/namespace.pl b/scripts/namespace.pl
diff --git a/usr/initramfs_data.S b/usr/initramfs_data.S
