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Commit 6358d6e8 authored by Nicholas Piggin's avatar Nicholas Piggin Committed by Masahiro Yamada
Browse files

kbuild: remove incremental linking option 



This removes the old `ld -r` incremental link option, which has not
been selected by any architecture since June 2017.

Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
Signed-off-by: default avatarMasahiro Yamada <yamada.masahiro@socionext.com>
parent 1fe7d2bb

Documentation/kbuild/makefiles.txt

+8 −2
Original line number Diff line number Diff line
@@ -153,8 +153,14 @@ 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.

	"$(AR) rcSTP" to merge these files into one built-in.o file.

	This is a thin archive without a symbol table, which makes it

	unsuitable as a linker input.



	The scripts/link-vmlinux.sh script later makes an aggregate

	built-in.o with "${AR} rcsTP", which creates the thin archive

	with a symbol table and an index, making it a valid input for

	the final vmlinux link passes.



	The order of files in $(obj-y) is significant.  Duplicates in

	the lists are allowed: the first instance will be linked into

arch/Kconfig

+0 −6
Original line number Diff line number Diff line
@@ -596,12 +596,6 @@ config CC_STACKPROTECTOR_AUTO 


endchoice



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.



config LD_DEAD_CODE_DATA_ELIMINATION

	bool

	help

scripts/Makefile.build

+11 −21
Original line number Diff line number Diff line
@@ -458,15 +458,13 @@ $(sort $(subdir-obj-y)): $(subdir-ym) ; 
#

ifdef builtin-target



ifdef CONFIG_THIN_ARCHIVES

# built-in.o archives are made with no symbol table or index which

# makes them small and fast, but unable to be used by the linker.

# scripts/link-vmlinux.sh builds an aggregate built-in.o with a symbol

# table and index.

cmd_make_builtin = rm -f $@; $(AR) rcSTP$(KBUILD_ARFLAGS)

cmd_make_empty_builtin = rm -f $@; $(AR) rcSTP$(KBUILD_ARFLAGS)

quiet_cmd_link_o_target = AR      $@

else

  cmd_make_builtin = $(LD) $(ld_flags) -r -o

  cmd_make_empty_builtin = rm -f $@; $(AR) rcs$(KBUILD_ARFLAGS)

  quiet_cmd_link_o_target = LD      $@

endif



# If the list of objects to link is empty, just create an empty built-in.o

cmd_link_o_target = $(if $(strip $(obj-y)),\
@@ -499,11 +497,8 @@ $(modorder-target): $(subdir-ym) FORCE 
ifdef lib-target

quiet_cmd_link_l_target = AR      $@



ifdef CONFIG_THIN_ARCHIVES

# lib target archives do get a symbol table and index

cmd_link_l_target = rm -f $@; $(AR) rcsTP$(KBUILD_ARFLAGS) $@ $(lib-y)

else

  cmd_link_l_target = rm -f $@; $(AR) rcs$(KBUILD_ARFLAGS) $@ $(lib-y)

endif



$(lib-target): $(lib-y) FORCE

	$(call if_changed,link_l_target)
@@ -551,13 +546,8 @@ $($(subst $(obj)/,,$(@:.o=-m)))), $^) 


cmd_link_multi-link = $(LD) $(ld_flags) -r -o $@ $(link_multi_deps) $(cmd_secanalysis)



ifdef CONFIG_THIN_ARCHIVES

quiet_cmd_link_multi-y = AR      $@

cmd_link_multi-y = rm -f $@; $(AR) rcSTP$(KBUILD_ARFLAGS) $@ $(link_multi_deps)

else

  quiet_cmd_link_multi-y = LD      $@

  cmd_link_multi-y = $(cmd_link_multi-link)

endif



quiet_cmd_link_multi-m = LD [M]  $@

cmd_link_multi-m = $(cmd_link_multi-link)

scripts/link-vmlinux.sh

+32 −59
Original line number Diff line number Diff line
@@ -55,13 +55,11 @@ info() 
#

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			\

				${KBUILD_VMLINUX_INIT}		\

				${KBUILD_VMLINUX_MAIN}

	fi

}



# Link of vmlinux.o used for section mismatch analysis
@@ -70,20 +68,13 @@ modpost_link() 
{

	local objects



	if [ -n "${CONFIG_THIN_ARCHIVES}" ]; then

	objects="--whole-archive				\

		built-in.o					\

		--no-whole-archive				\

		--start-group					\

		${KBUILD_VMLINUX_LIBS}				\

		--end-group"

	else

		objects="${KBUILD_VMLINUX_INIT}				\

			--start-group					\

			${KBUILD_VMLINUX_MAIN}				\

			${KBUILD_VMLINUX_LIBS}				\

			--end-group"

	fi



	${LD} ${LDFLAGS} -r -o ${1} ${objects}

}
@@ -96,7 +87,6 @@ vmlinux_link() 
	local objects



	if [ "${SRCARCH}" != "um" ]; then

		if [ -n "${CONFIG_THIN_ARCHIVES}" ]; then

		objects="--whole-archive			\

			built-in.o				\

			--no-whole-archive			\
@@ -104,19 +94,10 @@ vmlinux_link() 
			${KBUILD_VMLINUX_LIBS}			\

			--end-group				\

			${1}"

		else

			objects="${KBUILD_VMLINUX_INIT}			\

				--start-group				\

				${KBUILD_VMLINUX_MAIN}			\

				${KBUILD_VMLINUX_LIBS}			\

				--end-group				\

				${1}"

		fi



		${LD} ${LDFLAGS} ${LDFLAGS_vmlinux} -o ${2}	\

			-T ${lds} ${objects}

	else

		if [ -n "${CONFIG_THIN_ARCHIVES}" ]; then

		objects="-Wl,--whole-archive			\

			built-in.o				\

			-Wl,--no-whole-archive			\
@@ -124,14 +105,6 @@ vmlinux_link() 
			${KBUILD_VMLINUX_LIBS}			\

			-Wl,--end-group				\

			${1}"

		else

			objects="${KBUILD_VMLINUX_INIT}			\

				-Wl,--start-group			\

				${KBUILD_VMLINUX_MAIN}			\

				${KBUILD_VMLINUX_LIBS}			\

				-Wl,--end-group				\

				${1}"

		fi



		${CC} ${CFLAGS_vmlinux} -o ${2}			\

			-Wl,-T,${lds}				\