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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: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
hifive-unleashed-5.1
Nicholas Piggin 2018-02-11 00:25:03 +10:00 committed by Masahiro Yamada
parent 1fe7d2bb24
commit 6358d6e8b9
4 changed files with 49 additions and 86 deletions
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10
Documentation/kbuild/makefiles.txt
View File

@ -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

6
arch/Kconfig
View File

@ -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

32
scripts/Makefile.build
View File

@ -458,15 +458,13 @@ $(sort $(subdir-obj-y)): $(subdir-ym) ;
#
ifdef builtin-target
ifdef CONFIG_THIN_ARCHIVES
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
# 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 $@
# 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
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 archives do get a symbol table and index
cmd_link_l_target = rm -f $@; $(AR) rcsTP$(KBUILD_ARFLAGS) $@ $(lib-y)
$(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-y = AR $@
cmd_link_multi-y = rm -f $@; $(AR) rcSTP$(KBUILD_ARFLAGS) $@ $(link_multi_deps)
quiet_cmd_link_multi-m = LD [M] $@
cmd_link_multi-m = $(cmd_link_multi-link)

87
scripts/link-vmlinux.sh
View File

@ -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
info AR built-in.o
rm -f built-in.o;
${AR} rcsTP${KBUILD_ARFLAGS} built-in.o \
${KBUILD_VMLINUX_INIT} \
${KBUILD_VMLINUX_MAIN}
}
# Link of vmlinux.o used for section mismatch analysis
@ -70,20 +68,13 @@ modpost_link()
{
local objects
if [ -n "${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
objects="--whole-archive \
built-in.o \
--no-whole-archive \
--start-group \
${KBUILD_VMLINUX_LIBS} \
--end-group"
${LD} ${LDFLAGS} -r -o ${1} ${objects}
}
@ -96,46 +87,28 @@ vmlinux_link()
local objects
if [ "${SRCARCH}" != "um" ]; then
if [ -n "${CONFIG_THIN_ARCHIVES}" ]; 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
objects="--whole-archive \
built-in.o \
--no-whole-archive \
--start-group \
${KBUILD_VMLINUX_LIBS} \
--end-group \
${1}"
${LD} ${LDFLAGS} ${LDFLAGS_vmlinux} -o ${2} \
${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 \
-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
objects="-Wl,--whole-archive \
built-in.o \
-Wl,--no-whole-archive \
-Wl,--start-group \
${KBUILD_VMLINUX_LIBS} \
-Wl,--end-group \
${1}"
${CC} ${CFLAGS_vmlinux} -o ${2} \
-Wl,-T,${lds} \
${objects} \
${CC} ${CFLAGS_vmlinux} -o ${2} \
-Wl,-T,${lds} \
${objects} \
-lutil -lrt -lpthread
rm -f linux
fi