debug=false
+# Linker flags used:
+#
+# Informational:
+# --warn-common
+# -Map $EXE.map
+# --verbose
+#
+# Optimizations:
+# --sort-common reduces padding
+# --sort-section alignment reduces padding
+# --gc-sections throws out unused sections,
+# does not work for shared libs
+# -On Not used, maybe useful?
+#
+# List of files to link:
+# $l_list == --start-group -llib1 -llib2 --end-group
+# --start-group $O_FILES $A_FILES --end-group
+#
+# Shared library link:
+# -shared self-explanatory
+# -fPIC position-independent code
+# --enable-new-dtags ?
+# -z,combreloc ?
+# -soname="libbusybox.so.$BB_VER"
+# --undefined=lbb_main Seed name to start pulling from
+# (otherwise we'll need --whole-archive)
+# -static Not used, but may be useful! manpage:
+# "... This option can be used with -shared.
+# Doing so means that a shared library
+# is being created but that all of the library's
+# external references must be resolved by pulling
+# in entries from static libraries."
+
+
try() {
- added="$1"
- shift
- $debug && echo "Trying: $* $added"
- "$@" $added >busybox.map 2>busybox_ld.err
+ printf "%s\n" "Output of:" >$EXE.out
+ printf "%s\n" "$*" >>$EXE.out
+ printf "%s\n" "==========" >>$EXE.out
+ $debug && echo "Trying: $*"
+ $@ >>$EXE.out 2>&1
+ return $?
+}
+
+check_cc() {
+ tempname="$(mktemp tmp.XXXXXXXXXX)"
+ echo "int main(int argc,char**argv){return argv?argc:0;}" >"$tempname".c
+ # Can use "-o /dev/null", but older gcc tend to *unlink it* on failure! :(
+ # Was using "-xc /dev/null", but we need a valid C program.
+ # "eval" may be needed if CFLAGS can contain
+ # '... -D"BB_VER=KBUILD_STR(1.N.M)" ...'
+ # and we need shell to process quotes!
+ $CC $CFLAGS $LDFLAGS $1 "$tempname".c -o "$tempname" >/dev/null 2>&1
+ exitcode=$?
+ rm -f "$tempname" "$tempname".c "$tempname".o
+ return $exitcode
+}
+
+check_libc_is_glibc() {
+ tempname="$(mktemp tmp.XXXXXXXXXX)"
+ echo "\
+ #include <stdlib.h>
+ /* Apparently uclibc defines __GLIBC__ (compat trick?). Oh well. */
+ #if defined(__GLIBC__) && !defined(__UCLIBC__)
+ syntax error here
+ #endif
+ " >"$tempname".c
+ ! $CC $CFLAGS "$tempname".c -c -o "$tempname".o >/dev/null 2>&1
+ exitcode=$?
+ rm -f "$tempname" "$tempname".c "$tempname".o
+ return $exitcode
}
+EXE="$1"
+CC="$2"
+CFLAGS="$3"
+LDFLAGS="$4"
+O_FILES="$5"
+A_FILES="$6"
+LDLIBS="$7"
+
+# The --sort-section option is not supported by older versions of ld
+SORT_SECTION="-Wl,--sort-section,alignment"
+if ! check_cc "-Wl,--sort-section,alignment"; then
+ echo "Your linker does not support --sort-section,alignment"
+ SORT_SECTION=""
+fi
+
+START_GROUP="-Wl,--start-group"
+END_GROUP="-Wl,--end-group"
+INFO_OPTS() {
+ echo "-Wl,--warn-common -Wl,-Map,$EXE.map -Wl,--verbose"
+}
+
+# gold may not support --sort-common (yet)
+SORT_COMMON="-Wl,--sort-common"
+if ! check_cc "-Wl,--sort-common"; then
+ echo "Your linker does not support --sort-common"
+ SORT_COMMON=""
+fi
+
+# Static linking against glibc produces buggy executables
+# (glibc does not cope well with ld --gc-sections).
+# See sources.redhat.com/bugzilla/show_bug.cgi?id=3400
+# Note that glibc is unsuitable for static linking anyway.
+# We are removing -Wl,--gc-sections from link command line.
+GC_SECTIONS="-Wl,--gc-sections"
+if (. ./.config && test x"$CONFIG_STATIC" = x"y") then
+ if check_libc_is_glibc; then
+ echo "Static linking against glibc, can't use --gc-sections"
+ GC_SECTIONS=""
+ fi
+fi
+# The --gc-sections option is not supported by older versions of ld
+if test -n "$GC_SECTIONS"; then
+ if ! check_cc "$GC_SECTIONS"; then
+ echo "Your linker does not support $GC_SECTIONS"
+ GC_SECTIONS=""
+ fi
+fi
+
# Sanitize lib list (dups, extra spaces etc)
-#echo "BBOX_LIB_LIST=$BBOX_LIB_LIST"
-BBOX_LIB_LIST=`echo "$BBOX_LIB_LIST" | xargs -n1 | sort | uniq | xargs`
+LDLIBS=`echo "$LDLIBS" | xargs -n1 | sort | uniq | xargs`
# First link with all libs. If it fails, bail out
-l_list=`echo "$BBOX_LIB_LIST" | sed -e 's/ / -l/g' -e 's/^/-l/'`
-echo "Trying libraries: $BBOX_LIB_LIST"
-try "-Wl,--start-group $l_list -Wl,--end-group" "$@" \
+echo "Trying libraries: $LDLIBS"
+# "lib1 lib2 lib3" -> "-llib1 -llib2 -llib3"
+l_list=`echo " $LDLIBS " | sed -e 's: \([^- ][^ ]*\): -l\1:g'`
+test "x$l_list" != "x" && l_list="$START_GROUP $l_list $END_GROUP"
+try $CC $CFLAGS $LDFLAGS \
+ -o $EXE \
+ $SORT_COMMON \
+ $SORT_SECTION \
+ $GC_SECTIONS \
+ $START_GROUP $O_FILES $A_FILES $END_GROUP \
+ $l_list \
|| {
- echo "Failed: $* -Wl,--start-group $l_list -Wl,--end-group"
- cat busybox_ld.err
+ echo "Failed: $l_list"
+ cat $EXE.out
+ echo 'Note: if build needs additional libraries, put them in CONFIG_EXTRA_LDLIBS.'
+ echo 'Example: CONFIG_EXTRA_LDLIBS="pthread dl tirpc audit pam"'
exit 1
}
-mv busybox_unstripped busybox_unstripped.tmp
-# Now try to remove each lib and build without.
+# Now try to remove each lib and build without it.
# Stop when no lib can be removed.
-ever_discarded=false
-while test "$BBOX_LIB_LIST"; do
- $debug && echo "Trying libraries: $BBOX_LIB_LIST"
- all_needed=true
- for one in $BBOX_LIB_LIST; do
- without_one=`echo " $BBOX_LIB_LIST " | sed "s/ $one / /g" | xargs`
- l_list=`echo "$without_one" | sed -e 's/ / -l/g' -e 's/^/-l/'`
- $debug && echo "Trying -l options: $l_list"
- if try "-Wl,--start-group $l_list -Wl,--end-group" "$@"; then
- echo "Library $one is not needed"
- BBOX_LIB_LIST="$without_one"
- all_needed=false
- ever_discarded=true
+while test "$LDLIBS"; do
+ $debug && echo "Trying libraries: $LDLIBS"
+ dropped_non_first_lib=false
+ first_lib=true
+ for one in $LDLIBS; do
+ without_one=`echo " $LDLIBS " | sed "s/ $one / /g" | xargs`
+ # "lib1 lib2 lib3" -> "-llib1 -llib2 -llib3"
+ l_list=`echo " $without_one " | sed -e 's: \([^- ][^ ]*\): -l\1:g'`
+ test x"$l_list" != x"" && l_list="$START_GROUP $l_list $END_GROUP"
+ $debug && echo "Trying -l options: '$l_list'"
+ try $CC $CFLAGS $LDFLAGS \
+ -o $EXE \
+ $SORT_COMMON \
+ $SORT_SECTION \
+ $GC_SECTIONS \
+ $START_GROUP $O_FILES $A_FILES $END_GROUP \
+ $l_list
+ if test $? = 0; then
+ echo " Library $one is not needed, excluding it"
+ LDLIBS="$without_one"
+ $first_lib || dropped_non_first_lib=true
else
- echo "Library $one is needed"
+ echo " Library $one is needed, can't exclude it (yet)"
+ first_lib=false
fi
done
- # All libs were needed, can't remove any
- $all_needed && break
- # If there is no space, the list has just one lib.
- # I'm not sure that in this case lib really is 100% needed.
- # Let's try linking without it anyway... thus commented out.
- #echo "$BBOX_LIB_LIST" | grep -q ' ' || break
+ # We can stop trying to drop libs if either all libs were needed,
+ # or we excluded only the _first_ few.
+ # (else: we dropped some intermediate lib(s), maybe now we can succeed
+ # in dropping some of the preceding ones)
+ $dropped_non_first_lib || break
done
-mv busybox_unstripped.tmp busybox_unstripped
-$ever_discarded && {
- # Ok, make the binary
- echo "Final link with: $BBOX_LIB_LIST"
- l_list=`echo "$BBOX_LIB_LIST" | sed -e 's/ / -l/g' -e 's/^/-l/'`
- try "-Wl,--start-group $l_list -Wl,--end-group" "$@"
+# Make the binary with final, minimal list of libs
+echo "Final link with: ${LDLIBS:-<none>}"
+l_list=`echo " $LDLIBS " | sed -e 's: \([^- ][^ ]*\): -l\1:g'`
+test "x$l_list" != "x" && l_list="$START_GROUP $l_list $END_GROUP"
+# --verbose gives us gobs of info to stdout (e.g. linker script used)
+if ! test -f busybox_ldscript; then
+ try $CC $CFLAGS $LDFLAGS \
+ -o $EXE \
+ $SORT_COMMON \
+ $SORT_SECTION \
+ $GC_SECTIONS \
+ $START_GROUP $O_FILES $A_FILES $END_GROUP \
+ $l_list \
+ `INFO_OPTS` \
+ || {
+ cat $EXE.out
+ exit 1
+ }
+else
+ echo "Custom linker script 'busybox_ldscript' found, using it"
+ # Add SORT_BY_ALIGNMENT to linker script (found in $EXE.out):
+ # .rodata : { *(.rodata SORT_BY_ALIGNMENT(.rodata.*) .gnu.linkonce.r.*) }
+ # *(.data SORT_BY_ALIGNMENT(.data.*) .gnu.linkonce.d.*)
+ # *(.bss SORT_BY_ALIGNMENT(.bss.*) .gnu.linkonce.b.*)
+ # This will eliminate most of the padding (~3kb).
+ # Hmm, "ld --sort-section alignment" should do it too.
+ #
+ # There is a ld hack which is meant to decrease disk usage
+ # at the cost of more RAM usage (??!!) in standard ld script:
+ # /* Adjust the address for the data segment. We want to adjust up to
+ # the same address within the page on the next page up. */
+ # . = ALIGN (0x1000) - ((0x1000 - .) & (0x1000 - 1)); . = DATA_SEGMENT_ALIGN (0x1000, 0x1000);
+ # Replace it with:
+ # . = ALIGN (0x1000); . = DATA_SEGMENT_ALIGN (0x1000, 0x1000);
+ # to unconditionally align .data to the next page boundary,
+ # instead of "next page, plus current offset in this page"
+ try $CC $CFLAGS $LDFLAGS \
+ -o $EXE \
+ $SORT_COMMON \
+ $SORT_SECTION \
+ $GC_SECTIONS \
+ -Wl,-T,busybox_ldscript \
+ $START_GROUP $O_FILES $A_FILES $END_GROUP \
+ $l_list \
+ `INFO_OPTS` \
+ || {
+ cat $EXE.out
+ exit 1
+ }
+fi
+
+. ./.config
+
+sharedlib_dir="0_lib"
+
+if test "$CONFIG_BUILD_LIBBUSYBOX" = y; then
+ mkdir "$sharedlib_dir" 2>/dev/null
+ test -d "$sharedlib_dir" || {
+ echo "Cannot make directory $sharedlib_dir"
+ exit 1
+ }
+ ln -s "libbusybox.so.$BB_VER" "$sharedlib_dir"/libbusybox.so 2>/dev/null
+
+ # Yes, "ld -shared -static" is a thing. It's a shared library which is itself static.
+ LBB_STATIC=""
+ test "$CONFIG_FEATURE_LIBBUSYBOX_STATIC" = y && LBB_STATIC="-Wl,-static"
+
+ EXE="$sharedlib_dir/libbusybox.so.${BB_VER}_unstripped"
+ try $CC $CFLAGS $LDFLAGS \
+ -o $EXE \
+ -shared -fPIC $LBB_STATIC \
+ -Wl,--enable-new-dtags \
+ -Wl,-z,combreloc \
+ -Wl,-soname="libbusybox.so.$BB_VER" \
+ -Wl,--undefined=lbb_main \
+ $SORT_COMMON \
+ $SORT_SECTION \
+ $START_GROUP $A_FILES $END_GROUP \
+ $l_list \
+ `INFO_OPTS` \
+ || {
+ echo "Linking $EXE failed"
+ cat $EXE.out
+ exit 1
+ }
+ $STRIP -s --remove-section=.note --remove-section=.comment $EXE -o "$sharedlib_dir/libbusybox.so.$BB_VER"
+ chmod a+x "$sharedlib_dir/libbusybox.so.$BB_VER"
+ echo "libbusybox: $sharedlib_dir/libbusybox.so.$BB_VER"
+fi
+
+if test "$CONFIG_FEATURE_SHARED_BUSYBOX" = y; then
+ EXE="$sharedlib_dir/busybox_unstripped"
+ try $CC $CFLAGS $LDFLAGS \
+ -o $EXE \
+ $SORT_COMMON \
+ $SORT_SECTION \
+ $GC_SECTIONS \
+ $START_GROUP $O_FILES $END_GROUP \
+ -L"$sharedlib_dir" -lbusybox \
+ $l_list \
+ `INFO_OPTS` \
+ || {
+ echo "Linking $EXE failed"
+ cat $EXE.out
+ exit 1
+ }
+ $STRIP -s --remove-section=.note --remove-section=.comment $EXE -o "$sharedlib_dir/busybox"
+ echo "busybox linked against libbusybox: $sharedlib_dir/busybox"
+fi
+
+if test "$CONFIG_FEATURE_INDIVIDUAL" = y; then
+ echo "Linking individual applets against libbusybox (see $sharedlib_dir/*)"
+ gcc -DNAME_MAIN -E -include include/autoconf.h include/applets.h \
+ | grep -v "^#" \
+ | grep -v "^ *$" \
+ > applet_lst.tmp
+ while read name main junk; do
+
+ echo "\
+void lbb_prepare(const char *applet, char **argv);
+int $main(int argc, char **argv);
+
+int main(int argc, char **argv)
+{
+ lbb_prepare(\"$name\", argv);
+ return $main(argc, argv);
}
-exit 0 # Ensure "success" exit code
+" >"$sharedlib_dir/applet.c"
+
+ EXE="$sharedlib_dir/$name"
+ try $CC $CFLAGS $LDFLAGS "$sharedlib_dir/applet.c" \
+ -o $EXE \
+ $SORT_COMMON \
+ $SORT_SECTION \
+ $GC_SECTIONS \
+ -L"$sharedlib_dir" -lbusybox \
+ -Wl,--warn-common \
+ || {
+ echo "Linking $EXE failed"
+ cat $EXE.out
+ exit 1
+ }
+ rm -- "$sharedlib_dir/applet.c" $EXE.out
+ $STRIP -s --remove-section=.note --remove-section=.comment $EXE
+ # Let user see that we do something - list the names of created binaries:
+ echo "$EXE"
+
+ done <applet_lst.tmp
+fi
+
+# libbusybox.so is needed only for -lbusybox at link time,
+# it is not needed at runtime. Deleting to reduce confusion.
+rm "$sharedlib_dir"/libbusybox.so 2>/dev/null
+exit 0 # or else we may confuse make
projects / oweals / busybox.git / blobdiff