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authorMasahiro Yamada <yamada.masahiro@socionext.com>2019-01-17 09:10:03 +0900
committerMasahiro Yamada <yamada.masahiro@socionext.com>2019-01-28 09:11:17 +0900
commitdee9495303f2c6d63a20c43a26420765909898eb (patch)
tree743ef93dc34e18f12cd67d7379979ee4651e6c96
parent58156ba4468f1d0de166a4330374bc9df9b74efc (diff)
downloadlinux-dee9495303f2c6d63a20c43a26420765909898eb.tar.bz2
kbuild: remove top-level built-in.a
The symbol table in the final archive is unneeded; the linker does not require the symbol table after the --whole-archive option. Every object file in the archive is included in the link anyway. Pass thin archives from subdirectories directly to the linker, and remove the final archiving step. Fix up the document and comments as well. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Acked-by: Nicholas Piggin <npiggin@gmail.com>
-rw-r--r--Documentation/kbuild/makefiles.txt9
-rw-r--r--scripts/Makefile.build8
-rwxr-xr-xscripts/link-vmlinux.sh30
3 files changed, 10 insertions, 37 deletions
diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt
index bf28c47bfd72..48eab0bb1183 100644
--- a/Documentation/kbuild/makefiles.txt
+++ b/Documentation/kbuild/makefiles.txt
@@ -154,13 +154,8 @@ more details, with real examples.
Kbuild compiles all the $(obj-y) files. It then calls
"$(AR) rcSTP" to merge these files into one built-in.a 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.a 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.
+ This is a thin archive without a symbol table. It will be later
+ linked into vmlinux by scripts/link-vmlinux.sh
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/scripts/Makefile.build b/scripts/Makefile.build
index fd03d60f6c5a..681ab58a1548 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -394,14 +394,10 @@ $(obj)/%.asn1.c $(obj)/%.asn1.h: $(src)/%.asn1 $(objtree)/scripts/asn1_compiler
$(sort $(subdir-obj-y)): $(subdir-ym) ;
#
-# Rule to compile a set of .o files into one .o file
+# Rule to compile a set of .o files into one .a file (without symbol table)
#
ifdef builtin-target
-# built-in.a 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.a with a symbol
-# table and index.
quiet_cmd_ar_builtin = AR $@
cmd_ar_builtin = rm -f $@; \
$(AR) rcSTP$(KBUILD_ARFLAGS) $@ $(filter $(real-obj-y), $^)
@@ -426,7 +422,7 @@ $(modorder-target): $(subdir-ym) FORCE
$(Q)(cat /dev/null; $(modorder-cmds)) > $@
#
-# Rule to compile a set of .o files into one .a file
+# Rule to compile a set of .o files into one .a file (with symbol table)
#
ifdef lib-target
quiet_cmd_link_l_target = AR $@
diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
index c8cf45362bd6..4788def71358 100755
--- a/scripts/link-vmlinux.sh
+++ b/scripts/link-vmlinux.sh
@@ -44,24 +44,6 @@ info()
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.a output file
-#
-archive_builtin()
-{
- info AR built-in.a
- rm -f built-in.a;
- ${AR} rcsTP${KBUILD_ARFLAGS} built-in.a \
- ${KBUILD_VMLINUX_INIT} \
- ${KBUILD_VMLINUX_MAIN}
-}
-
# Link of vmlinux.o used for section mismatch analysis
# ${1} output file
modpost_link()
@@ -69,7 +51,8 @@ modpost_link()
local objects
objects="--whole-archive \
- built-in.a \
+ ${KBUILD_VMLINUX_INIT} \
+ ${KBUILD_VMLINUX_MAIN} \
--no-whole-archive \
--start-group \
${KBUILD_VMLINUX_LIBS} \
@@ -88,7 +71,8 @@ vmlinux_link()
if [ "${SRCARCH}" != "um" ]; then
objects="--whole-archive \
- built-in.a \
+ ${KBUILD_VMLINUX_INIT} \
+ ${KBUILD_VMLINUX_MAIN} \
--no-whole-archive \
--start-group \
${KBUILD_VMLINUX_LIBS} \
@@ -99,7 +83,8 @@ vmlinux_link()
-T ${lds} ${objects}
else
objects="-Wl,--whole-archive \
- built-in.a \
+ ${KBUILD_VMLINUX_INIT} \
+ ${KBUILD_VMLINUX_MAIN} \
-Wl,--no-whole-archive \
-Wl,--start-group \
${KBUILD_VMLINUX_LIBS} \
@@ -160,7 +145,6 @@ cleanup()
rm -f .tmp_System.map
rm -f .tmp_kallsyms*
rm -f .tmp_vmlinux*
- rm -f built-in.a
rm -f System.map
rm -f vmlinux
rm -f vmlinux.o
@@ -217,8 +201,6 @@ fi;
# final build of init/
${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init
-archive_builtin
-
#link vmlinux.o
info LD vmlinux.o
modpost_link vmlinux.o