src/kernel/linux/v4.14/scripts/link-vmlinux.sh - T103 - Gitiles

 #!/bin/sh
 # SPDX-License-Identifier: GPL-2.0
 #
 # link vmlinux
 #
 # vmlinux is linked from the objects selected by $(KBUILD_VMLINUX_INIT) and
 # $(KBUILD_VMLINUX_MAIN) and $(KBUILD_VMLINUX_LIBS). Most are built-in.o files
 # from top-level directories in the kernel tree, others are specified in
 # arch/$(ARCH)/Makefile. Ordering when linking is important, and
 # $(KBUILD_VMLINUX_INIT) must be first. $(KBUILD_VMLINUX_LIBS) are archives
 # which are linked conditionally (not within --whole-archive), and do not
 # require symbol indexes added.
 #
 # vmlinux
 #   ^
 #   |
 #   +-< $(KBUILD_VMLINUX_INIT)
 #   |   +--< init/version.o + more
 #   |
 #   +--< $(KBUILD_VMLINUX_MAIN)
 #   |    +--< drivers/built-in.o mm/built-in.o + more
 #   |
 #   +--< $(KBUILD_VMLINUX_LIBS)
 #   |    +--< lib/lib.a + more
 #   |
 #   +-< ${kallsymso} (see description in KALLSYMS section)
 #
 # vmlinux version (uname -v) cannot be updated during normal
 # descending-into-subdirs phase since we do not yet know if we need to
 # update vmlinux.
 # Therefore this step is delayed until just before final link of vmlinux.
 #
 # System.map is generated to document addresses of all kernel symbols

 # Error out on error
 set -e

 # Nice output in kbuild format
 # Will be supressed by "make -s"
 info()
 {
 	if [ "${quiet}" != "silent_" ]; then
 		printf "  %-7s %s\n" ${1} ${2}
 	fi
 }

 # Thin archive build here makes a final archive with symbol table and indexes
 # from vmlinux objects INIT and MAIN, which can be used as input to linker.
 # KBUILD_VMLINUX_LIBS archives should already have symbol table and indexes
 # added.
 #
 # Traditional incremental style of link does not require this step
 #
 # built-in.o 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			\
 					${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
 		fi
 	fi
 }

 # If CONFIG_LTO_CLANG is selected, collect generated symbol versions into
 # .tmp_symversions
 modversions()
 {
 	if [ -z "${CONFIG_LTO_CLANG}" ]; then
 		return
 	fi

 	if [ -z "${CONFIG_MODVERSIONS}" ]; then
 		return
 	fi

 	rm -f .tmp_symversions

 	for a in built-in.o ${KBUILD_VMLINUX_LIBS}; do
 		for o in $(${AR} t $a); do
 			if [ -f ${o}.symversions ]; then
 				cat ${o}.symversions >> .tmp_symversions
 			fi
 		done
 	done

 	echo "-T .tmp_symversions"
 }

 # Link of vmlinux.o used for section mismatch analysis
 # ${1} output file
 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

 	if [ -n "${CONFIG_LTO_CLANG}" ]; then
 		# This might take a while, so indicate that we're doing
 		# an LTO link
 		info LTO vmlinux.o
 	else
 		info LD vmlinux.o
 	fi

 	${LD} ${LDFLAGS} -r -o ${1} $(modversions) ${objects}
 }

 # If CONFIG_LTO_CLANG is selected, we postpone running recordmcount until
 # we have compiled LLVM IR to an object file.
 recordmcount()
 {
 	if [ -z "${CONFIG_LTO_CLANG}" ]; then
 		return
 	fi

 	if [ -n "${CONFIG_FTRACE_MCOUNT_RECORD}" ]; then
 		scripts/recordmcount ${RECORDMCOUNT_FLAGS} $*
 	fi
 }

 # Link of vmlinux
 # ${1} - optional extra .o files
 # ${2} - output file
 vmlinux_link()
 {
 	local lds="${objtree}/${KBUILD_LDS}"
 	local objects

 	if [ "${SRCARCH}" != "um" ]; then
 		local ld=${LD}
 		local ldflags="${LDFLAGS} ${LDFLAGS_vmlinux}"

 		if [ -n "${LDFINAL_vmlinux}" ]; then
 			ld=${LDFINAL_vmlinux}
 			ldflags="${LDFLAGS_FINAL_vmlinux} ${LDFLAGS_vmlinux}"
 		fi

 		if [[ -n "${CONFIG_THIN_ARCHIVES}" && -z "${CONFIG_LTO_CLANG}" ]]; then
 			objects="--whole-archive 			\
 				built-in.o				\
 				--no-whole-archive			\
 				--start-group				\
 				${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} -o ${2} -T ${lds} ${objects}
 	else
 		if [ -n "${CONFIG_THIN_ARCHIVES}" ]; then
 			objects="-Wl,--whole-archive			\
 				built-in.o				\
 				-Wl,--no-whole-archive			\
 				-Wl,--start-group			\
 				${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}					\
 			${objects}					\
 			-lutil -lrt -lpthread
 		rm -f linux
 	fi
 }

 # Create ${2} .o file with all symbols from the ${1} object file
 kallsyms()
 {
 	info KSYM ${2}
 	local kallsymopt;

 	if [ -n "${CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX}" ]; then
 		kallsymopt="${kallsymopt} --symbol-prefix=_"
 	fi

 	if [ -n "${CONFIG_KALLSYMS_ALL}" ]; then
 		kallsymopt="${kallsymopt} --all-symbols"
 	fi

 	if [ -n "${CONFIG_KALLSYMS_ABSOLUTE_PERCPU}" ]; then
 		kallsymopt="${kallsymopt} --absolute-percpu"
 	fi

 	if [ -n "${CONFIG_KALLSYMS_BASE_RELATIVE}" ]; then
 		kallsymopt="${kallsymopt} --base-relative"
 	fi

 	local aflags="${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL}               \
 		      ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS}"

 	local afile="`basename ${2} .o`.S"

 	${NM} -n ${1} | scripts/kallsyms ${kallsymopt} > ${afile}
 	${CC} ${aflags} -c -o ${2} ${afile}
 }

 # Create map file with all symbols from ${1}
 # See mksymap for additional details
 mksysmap()
 {
 	${CONFIG_SHELL} "${srctree}/scripts/mksysmap" ${1} ${2}
 }

 sortextable()
 {
 	${objtree}/scripts/sortextable ${1}
 }

 # Delete output files in case of error
 cleanup()
 {
 	rm -f .old_version
 	rm -f .tmp_System.map
 	rm -f .tmp_kallsyms*
 	rm -f .tmp_version
 	rm -f .tmp_symversions
 	rm -f .tmp_vmlinux*
 	rm -f built-in.o
 	rm -f System.map
 	rm -f vmlinux
 	rm -f vmlinux.o
 }

 on_exit()
 {
 	if [ $? -ne 0 ]; then
 		cleanup
 	fi
 }
 trap on_exit EXIT

 on_signals()
 {
 	exit 1
 }
 trap on_signals HUP INT QUIT TERM

 #
 #
 # Use "make V=1" to debug this script
 case "${KBUILD_VERBOSE}" in
 *1*)
 	set -x
 	;;
 esac

 if [ "$1" = "clean" ]; then
 	cleanup
 	exit 0
 fi

 # We need access to CONFIG_ symbols
 case "${KCONFIG_CONFIG}" in
 */*)
 	. "${KCONFIG_CONFIG}"
 	;;
 *)
 	# Force using a file from the current directory
 	. "./${KCONFIG_CONFIG}"
 esac

 # Update version
 info GEN .version
 if [ ! -r .version ]; then
 	rm -f .version;
 	echo 1 >.version;
 else
 	mv .version .old_version;
 	expr 0$(cat .old_version) + 1 >.version;
 fi;

 # final build of init/
 ${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init GCC_PLUGINS_CFLAGS="${GCC_PLUGINS_CFLAGS}"

 archive_builtin

 #link vmlinux.o
 modpost_link vmlinux.o

 # modpost vmlinux.o to check for section mismatches
 ${MAKE} -f "${srctree}/scripts/Makefile.modpost" vmlinux.o

 if [ -n "${CONFIG_LTO_CLANG}" ]; then
 	# Re-use vmlinux.o, so we can avoid the slow LTO link step in
 	# vmlinux_link
 	KBUILD_VMLINUX_INIT=
 	KBUILD_VMLINUX_MAIN=vmlinux.o
 	KBUILD_VMLINUX_LIBS=

 	# Call recordmcount if needed
 	recordmcount vmlinux.o
 fi

 kallsymso=""
 kallsyms_vmlinux=""
 if [ -n "${CONFIG_KALLSYMS}" ]; then

 	# kallsyms support
 	# Generate section listing all symbols and add it into vmlinux
 	# It's a three step process:
 	# 1)  Link .tmp_vmlinux1 so it has all symbols and sections,
 	#     but __kallsyms is empty.
 	#     Running kallsyms on that gives us .tmp_kallsyms1.o with
 	#     the right size
 	# 2)  Link .tmp_vmlinux2 so it now has a __kallsyms section of
 	#     the right size, but due to the added section, some
 	#     addresses have shifted.
 	#     From here, we generate a correct .tmp_kallsyms2.o
 	# 3)  That link may have expanded the kernel image enough that
 	#     more linker branch stubs / trampolines had to be added, which
 	#     introduces new names, which further expands kallsyms. Do another
 	#     pass if that is the case. In theory it's possible this results
 	#     in even more stubs, but unlikely.
 	#     KALLSYMS_EXTRA_PASS=1 may also used to debug or work around
 	#     other bugs.
 	# 4)  The correct ${kallsymso} is linked into the final vmlinux.
 	#
 	# a)  Verify that the System.map from vmlinux matches the map from
 	#     ${kallsymso}.

 	kallsymso=.tmp_kallsyms2.o
 	kallsyms_vmlinux=.tmp_vmlinux2

 	# step 1
 	vmlinux_link "" .tmp_vmlinux1
 	kallsyms .tmp_vmlinux1 .tmp_kallsyms1.o

 	# step 2
 	vmlinux_link .tmp_kallsyms1.o .tmp_vmlinux2
 	kallsyms .tmp_vmlinux2 .tmp_kallsyms2.o

 	# step 3
 	size1=$(stat -c "%s" .tmp_kallsyms1.o)
 	size2=$(stat -c "%s" .tmp_kallsyms2.o)

 	if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then
 		kallsymso=.tmp_kallsyms3.o
 		kallsyms_vmlinux=.tmp_vmlinux3

 		vmlinux_link .tmp_kallsyms2.o .tmp_vmlinux3

 		kallsyms .tmp_vmlinux3 .tmp_kallsyms3.o
 	fi
 fi

 info LD vmlinux
 vmlinux_link "${kallsymso}" vmlinux

 if [ -n "${CONFIG_BUILDTIME_EXTABLE_SORT}" ]; then
 	info SORTEX vmlinux
 	sortextable vmlinux
 fi

 info SYSMAP System.map
 mksysmap vmlinux System.map

 # step a (see comment above)
 if [ -n "${CONFIG_KALLSYMS}" ]; then
 	mksysmap ${kallsyms_vmlinux} .tmp_System.map

 	if ! cmp -s System.map .tmp_System.map; then
 		echo >&2 Inconsistent kallsyms data
 		echo >&2 Try "make KALLSYMS_EXTRA_PASS=1" as a workaround
 		exit 1
 	fi
 fi

 # We made a new kernel - delete old version file
 rm -f .old_version
	#!/bin/sh
	# SPDX-License-Identifier: GPL-2.0
	#
	# link vmlinux
	#
	# vmlinux is linked from the objects selected by $(KBUILD_VMLINUX_INIT) and
	# $(KBUILD_VMLINUX_MAIN) and $(KBUILD_VMLINUX_LIBS). Most are built-in.o files
	# from top-level directories in the kernel tree, others are specified in
	# arch/$(ARCH)/Makefile. Ordering when linking is important, and
	# $(KBUILD_VMLINUX_INIT) must be first. $(KBUILD_VMLINUX_LIBS) are archives
	# which are linked conditionally (not within --whole-archive), and do not
	# require symbol indexes added.
	#
	# vmlinux
	# ^
	# \|
	# +-< $(KBUILD_VMLINUX_INIT)
	# \| +--< init/version.o + more
	# \|
	# +--< $(KBUILD_VMLINUX_MAIN)
	# \| +--< drivers/built-in.o mm/built-in.o + more
	# \|
	# +--< $(KBUILD_VMLINUX_LIBS)
	# \| +--< lib/lib.a + more
	# \|
	# +-< ${kallsymso} (see description in KALLSYMS section)
	#
	# vmlinux version (uname -v) cannot be updated during normal
	# descending-into-subdirs phase since we do not yet know if we need to
	# update vmlinux.
	# Therefore this step is delayed until just before final link of vmlinux.
	#
	# System.map is generated to document addresses of all kernel symbols

	# Error out on error
	set -e

	# Nice output in kbuild format
	# Will be supressed by "make -s"
	info()
	{
	if [ "${quiet}" != "silent_" ]; then
	printf " %-7s %s\n" ${1} ${2}
	fi
	}

	# Thin archive build here makes a final archive with symbol table and indexes
	# from vmlinux objects INIT and MAIN, which can be used as input to linker.
	# KBUILD_VMLINUX_LIBS archives should already have symbol table and indexes
	# added.
	#
	# Traditional incremental style of link does not require this step
	#
	# built-in.o 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 \
	${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
	fi
	fi
	}

	# If CONFIG_LTO_CLANG is selected, collect generated symbol versions into
	# .tmp_symversions
	modversions()
	{
	if [ -z "${CONFIG_LTO_CLANG}" ]; then
	return
	fi

	if [ -z "${CONFIG_MODVERSIONS}" ]; then
	return
	fi

	rm -f .tmp_symversions

	for a in built-in.o ${KBUILD_VMLINUX_LIBS}; do
	for o in $(${AR} t $a); do
	if [ -f ${o}.symversions ]; then
	cat ${o}.symversions >> .tmp_symversions
	fi
	done
	done

	echo "-T .tmp_symversions"
	}

	# Link of vmlinux.o used for section mismatch analysis
	# ${1} output file
	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

	if [ -n "${CONFIG_LTO_CLANG}" ]; then
	# This might take a while, so indicate that we're doing
	# an LTO link
	info LTO vmlinux.o
	else
	info LD vmlinux.o
	fi

	${LD} ${LDFLAGS} -r -o ${1} $(modversions) ${objects}
	}

	# If CONFIG_LTO_CLANG is selected, we postpone running recordmcount until
	# we have compiled LLVM IR to an object file.
	recordmcount()
	{
	if [ -z "${CONFIG_LTO_CLANG}" ]; then
	return
	fi

	if [ -n "${CONFIG_FTRACE_MCOUNT_RECORD}" ]; then
	scripts/recordmcount ${RECORDMCOUNT_FLAGS} $*
	fi
	}

	# Link of vmlinux
	# ${1} - optional extra .o files
	# ${2} - output file
	vmlinux_link()
	{
	local lds="${objtree}/${KBUILD_LDS}"
	local objects

	if [ "${SRCARCH}" != "um" ]; then
	local ld=${LD}
	local ldflags="${LDFLAGS} ${LDFLAGS_vmlinux}"

	if [ -n "${LDFINAL_vmlinux}" ]; then
	ld=${LDFINAL_vmlinux}
	ldflags="${LDFLAGS_FINAL_vmlinux} ${LDFLAGS_vmlinux}"
	fi

	if [[ -n "${CONFIG_THIN_ARCHIVES}" && -z "${CONFIG_LTO_CLANG}" ]]; then
	objects="--whole-archive \
	built-in.o \
	--no-whole-archive \
	--start-group \
	${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} -o ${2} -T ${lds} ${objects}
	else
	if [ -n "${CONFIG_THIN_ARCHIVES}" ]; then
	objects="-Wl,--whole-archive \
	built-in.o \
	-Wl,--no-whole-archive \
	-Wl,--start-group \
	${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} \
	${objects} \
	-lutil -lrt -lpthread
	rm -f linux
	fi
	}

	# Create ${2} .o file with all symbols from the ${1} object file
	kallsyms()
	{
	info KSYM ${2}
	local kallsymopt;

	if [ -n "${CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX}" ]; then
	kallsymopt="${kallsymopt} --symbol-prefix=_"
	fi

	if [ -n "${CONFIG_KALLSYMS_ALL}" ]; then
	kallsymopt="${kallsymopt} --all-symbols"
	fi

	if [ -n "${CONFIG_KALLSYMS_ABSOLUTE_PERCPU}" ]; then
	kallsymopt="${kallsymopt} --absolute-percpu"
	fi

	if [ -n "${CONFIG_KALLSYMS_BASE_RELATIVE}" ]; then
	kallsymopt="${kallsymopt} --base-relative"
	fi

	local aflags="${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL} \
	${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS}"

	local afile="`basename ${2} .o`.S"

	${NM} -n ${1} \| scripts/kallsyms ${kallsymopt} > ${afile}
	${CC} ${aflags} -c -o ${2} ${afile}
	}

	# Create map file with all symbols from ${1}
	# See mksymap for additional details
	mksysmap()
	{
	${CONFIG_SHELL} "${srctree}/scripts/mksysmap" ${1} ${2}
	}

	sortextable()
	{
	${objtree}/scripts/sortextable ${1}
	}

	# Delete output files in case of error
	cleanup()
	{
	rm -f .old_version
	rm -f .tmp_System.map
	rm -f .tmp_kallsyms*
	rm -f .tmp_version
	rm -f .tmp_symversions
	rm -f .tmp_vmlinux*
	rm -f built-in.o
	rm -f System.map
	rm -f vmlinux
	rm -f vmlinux.o
	}

	on_exit()
	{
	if [ $? -ne 0 ]; then
	cleanup
	fi
	}
	trap on_exit EXIT

	on_signals()
	{
	exit 1
	}
	trap on_signals HUP INT QUIT TERM

	#
	#
	# Use "make V=1" to debug this script
	case "${KBUILD_VERBOSE}" in
	1)
	set -x
	;;
	esac

	if [ "$1" = "clean" ]; then
	cleanup
	exit 0
	fi

	# We need access to CONFIG_ symbols
	case "${KCONFIG_CONFIG}" in
	/)
	. "${KCONFIG_CONFIG}"
	;;
	*)
	# Force using a file from the current directory
	. "./${KCONFIG_CONFIG}"
	esac

	# Update version
	info GEN .version
	if [ ! -r .version ]; then
	rm -f .version;
	echo 1 >.version;
	else
	mv .version .old_version;
	expr 0$(cat .old_version) + 1 >.version;
	fi;

	# final build of init/
	${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init GCC_PLUGINS_CFLAGS="${GCC_PLUGINS_CFLAGS}"

	archive_builtin

	#link vmlinux.o
	modpost_link vmlinux.o

	# modpost vmlinux.o to check for section mismatches
	${MAKE} -f "${srctree}/scripts/Makefile.modpost" vmlinux.o

	if [ -n "${CONFIG_LTO_CLANG}" ]; then
	# Re-use vmlinux.o, so we can avoid the slow LTO link step in
	# vmlinux_link
	KBUILD_VMLINUX_INIT=
	KBUILD_VMLINUX_MAIN=vmlinux.o
	KBUILD_VMLINUX_LIBS=

	# Call recordmcount if needed
	recordmcount vmlinux.o
	fi

	kallsymso=""
	kallsyms_vmlinux=""
	if [ -n "${CONFIG_KALLSYMS}" ]; then

	# kallsyms support
	# Generate section listing all symbols and add it into vmlinux
	# It's a three step process:
	# 1) Link .tmp_vmlinux1 so it has all symbols and sections,
	# but __kallsyms is empty.
	# Running kallsyms on that gives us .tmp_kallsyms1.o with
	# the right size
	# 2) Link .tmp_vmlinux2 so it now has a __kallsyms section of
	# the right size, but due to the added section, some
	# addresses have shifted.
	# From here, we generate a correct .tmp_kallsyms2.o
	# 3) That link may have expanded the kernel image enough that
	# more linker branch stubs / trampolines had to be added, which
	# introduces new names, which further expands kallsyms. Do another
	# pass if that is the case. In theory it's possible this results
	# in even more stubs, but unlikely.
	# KALLSYMS_EXTRA_PASS=1 may also used to debug or work around
	# other bugs.
	# 4) The correct ${kallsymso} is linked into the final vmlinux.
	#
	# a) Verify that the System.map from vmlinux matches the map from
	# ${kallsymso}.

	kallsymso=.tmp_kallsyms2.o
	kallsyms_vmlinux=.tmp_vmlinux2

	# step 1
	vmlinux_link "" .tmp_vmlinux1
	kallsyms .tmp_vmlinux1 .tmp_kallsyms1.o

	# step 2
	vmlinux_link .tmp_kallsyms1.o .tmp_vmlinux2
	kallsyms .tmp_vmlinux2 .tmp_kallsyms2.o

	# step 3
	size1=$(stat -c "%s" .tmp_kallsyms1.o)
	size2=$(stat -c "%s" .tmp_kallsyms2.o)

	if [ $size1 -ne $size2 ] \|\| [ -n "${KALLSYMS_EXTRA_PASS}" ]; then
	kallsymso=.tmp_kallsyms3.o
	kallsyms_vmlinux=.tmp_vmlinux3

	vmlinux_link .tmp_kallsyms2.o .tmp_vmlinux3

	kallsyms .tmp_vmlinux3 .tmp_kallsyms3.o
	fi
	fi

	info LD vmlinux
	vmlinux_link "${kallsymso}" vmlinux

	if [ -n "${CONFIG_BUILDTIME_EXTABLE_SORT}" ]; then
	info SORTEX vmlinux
	sortextable vmlinux
	fi

	info SYSMAP System.map
	mksysmap vmlinux System.map

	# step a (see comment above)
	if [ -n "${CONFIG_KALLSYMS}" ]; then
	mksysmap ${kallsyms_vmlinux} .tmp_System.map

	if ! cmp -s System.map .tmp_System.map; then
	echo >&2 Inconsistent kallsyms data
	echo >&2 Try "make KALLSYMS_EXTRA_PASS=1" as a workaround
	exit 1
	fi
	fi

	# We made a new kernel - delete old version file
	rm -f .old_version