diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt index 71e9feefb63c..750aea9edd35 100644 --- a/Documentation/kbuild/makefiles.txt +++ b/Documentation/kbuild/makefiles.txt @@ -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 diff --git a/arch/Kconfig b/arch/Kconfig index 76c0b54443b1..8e0d665c8d53 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -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 diff --git a/scripts/Makefile.build b/scripts/Makefile.build index fff770983960..672cf5bfd724 100644 --- a/scripts/Makefile.build +++ b/scripts/Makefile.build @@ -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 = $(cmd_link_multi-link) diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh index be56a1153014..601ca8b528b3 100755 --- a/scripts/link-vmlinux.sh +++ b/scripts/link-vmlinux.sh @@ -55,13 +55,11 @@ info() # archive_builtin() { - if [ -n "${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