13 # --sort-common reduces padding
14 # --sort-section alignment reduces padding
15 # --gc-sections throws out unused sections,
16 # does not work for shared libs
17 # -On Not used, maybe useful?
19 # List of files to link:
20 # $l_list == --start-group -llib1 -llib2 --end-group
21 # --start-group $O_FILES $A_FILES --end-group
23 # Shared library link:
24 # -shared self-explanatory
25 # -fPIC position-independent code
26 # --enable-new-dtags ?
28 # -soname="libbusybox.so.$BB_VER"
29 # --undefined=lbb_main Seed name to start pulling from
30 # (otherwise we'll need --whole-archive)
31 # -static Not used, but may be useful! manpage:
32 # "... This option can be used with -shared.
33 # Doing so means that a shared library
34 # is being created but that all of the library's
35 # external references must be resolved by pulling
36 # in entries from static libraries."
40 printf "%s\n" "Output of:" >$EXE.out
41 printf "%s\n" "$*" >>$EXE.out
42 printf "%s\n" "==========" >>$EXE.out
43 $debug && echo "Trying: $*"
49 local tempname="$(mktemp)"
51 echo "int main(int argc,char**argv){return argv?argc:0;}" >"$tempname".c
52 # Can use "-o /dev/null", but older gcc tend to *unlink it* on failure! :(
53 # Was using "-xc /dev/null", but we need a valid C program.
54 # "eval" may be needed is CFLAGS can contain
55 # '... -D"BB_VER=KBUILD_STR(1.N.M)" ...'
56 # and we need shell to process quotes!
57 $CC $CFLAGS $1 "$tempname".c -o "$tempname" >/dev/null 2>&1
59 rm -f "$tempname" "$tempname".c "$tempname".o
63 check_libc_is_glibc() {
64 local tempname="$(mktemp)"
68 /* Apparently uclibc defines __GLIBC__ (compat trick?). Oh well. */
69 #if defined(__GLIBC__) && !defined(__UCLIBC__)
73 ! $CC $CFLAGS "$tempname".c -c -o "$tempname".o >/dev/null 2>&1
75 rm -f "$tempname" "$tempname".c "$tempname".o
87 # The --sort-section option is not supported by older versions of ld
88 SORT_SECTION="-Wl,--sort-section,alignment"
89 if ! check_cc "-Wl,--sort-section,alignment"; then
90 echo "Your linker does not support --sort-section,alignment"
94 START_GROUP="-Wl,--start-group"
95 END_GROUP="-Wl,--end-group"
96 INFO_OPTS="-Wl,--warn-common -Wl,-Map,$EXE.map -Wl,--verbose"
98 # gold may not support --sort-common (yet)
99 SORT_COMMON="-Wl,--sort-common"
100 if ! check_cc "-Wl,--sort-common"; then
101 echo "Your linker does not support --sort-common"
105 # Static linking against glibc produces buggy executables
106 # (glibc does not cope well with ld --gc-sections).
107 # See sources.redhat.com/bugzilla/show_bug.cgi?id=3400
108 # Note that glibc is unsuitable for static linking anyway.
109 # We are removing -Wl,--gc-sections from link command line.
110 GC_SECTIONS="-Wl,--gc-sections"
111 if (. ./.config && test x"$CONFIG_STATIC" = x"y") then
112 if check_libc_is_glibc; then
113 echo "Static linking against glibc, can't use --gc-sections"
117 # The --gc-sections option is not supported by older versions of ld
118 if test -n "$GC_SECTIONS"; then
119 if ! check_cc "$GC_SECTIONS"; then
120 echo "Your linker does not support $GC_SECTIONS"
125 # Sanitize lib list (dups, extra spaces etc)
126 LDLIBS=`echo "$LDLIBS" | xargs -n1 | sort | uniq | xargs`
128 # First link with all libs. If it fails, bail out
129 echo "Trying libraries: $LDLIBS"
130 # "lib1 lib2 lib3" -> "-llib1 -llib2 -llib3"
131 l_list=`echo " $LDLIBS " | sed -e 's: \([^- ][^ ]*\): -l\1:g'`
132 test "x$l_list" != "x" && l_list="$START_GROUP $l_list $END_GROUP"
133 try $CC $CFLAGS $LDFLAGS \
138 $START_GROUP $O_FILES $A_FILES $END_GROUP \
141 echo "Failed: $l_list"
146 # Now try to remove each lib and build without it.
147 # Stop when no lib can be removed.
148 while test "$LDLIBS"; do
149 $debug && echo "Trying libraries: $LDLIBS"
152 for one in $LDLIBS; do
153 without_one=`echo " $LDLIBS " | sed "s/ $one / /g" | xargs`
154 # "lib1 lib2 lib3" -> "-llib1 -llib2 -llib3"
155 l_list=`echo " $without_one " | sed -e 's: \([^- ][^ ]*\): -l\1:g'`
156 test x"$l_list" != x"" && l_list="$START_GROUP $l_list $END_GROUP"
157 $debug && echo "Trying -l options: '$l_list'"
158 try $CC $CFLAGS $LDFLAGS \
163 $START_GROUP $O_FILES $A_FILES $END_GROUP \
166 echo " Library $one is not needed, excluding it"
167 LDLIBS="$without_one"
171 echo " Library $one is needed, can't exclude it (yet)"
175 # All libs were needed, can't remove any
177 # Optimization: was the last tried lib needed?
178 if $last_needed; then
179 # Was it the only one lib left? Don't test again then.
180 { echo "$LDLIBS" | grep -q ' '; } || break
184 # Make the binary with final, minimal list of libs
185 echo "Final link with: ${LDLIBS:-<none>}"
186 l_list=`echo " $LDLIBS " | sed -e 's: \([^- ][^ ]*\): -l\1:g'`
187 test "x$l_list" != "x" && l_list="$START_GROUP $l_list $END_GROUP"
188 # --verbose gives us gobs of info to stdout (e.g. linker script used)
189 if ! test -f busybox_ldscript; then
190 try $CC $CFLAGS $LDFLAGS \
195 $START_GROUP $O_FILES $A_FILES $END_GROUP \
203 echo "Custom linker script 'busybox_ldscript' found, using it"
204 # Add SORT_BY_ALIGNMENT to linker script (found in $EXE.out):
205 # .rodata : { *(.rodata SORT_BY_ALIGNMENT(.rodata.*) .gnu.linkonce.r.*) }
206 # *(.data SORT_BY_ALIGNMENT(.data.*) .gnu.linkonce.d.*)
207 # *(.bss SORT_BY_ALIGNMENT(.bss.*) .gnu.linkonce.b.*)
208 # This will eliminate most of the padding (~3kb).
209 # Hmm, "ld --sort-section alignment" should do it too.
210 try $CC $CFLAGS $LDFLAGS \
215 -Wl,-T,busybox_ldscript \
216 $START_GROUP $O_FILES $A_FILES $END_GROUP \
227 sharedlib_dir="0_lib"
229 if test "$CONFIG_BUILD_LIBBUSYBOX" = y; then
230 mkdir "$sharedlib_dir" 2>/dev/null
231 test -d "$sharedlib_dir" || {
232 echo "Cannot make directory $sharedlib_dir"
235 ln -s "libbusybox.so.$BB_VER" "$sharedlib_dir"/libbusybox.so 2>/dev/null
237 EXE="$sharedlib_dir/libbusybox.so.${BB_VER}_unstripped"
238 try $CC $CFLAGS $LDFLAGS \
241 -Wl,--enable-new-dtags \
243 -Wl,-soname="libbusybox.so.$BB_VER" \
244 -Wl,--undefined=lbb_main \
247 $START_GROUP $A_FILES $END_GROUP \
251 echo "Linking $EXE failed"
255 $STRIP -s --remove-section=.note --remove-section=.comment $EXE -o "$sharedlib_dir/libbusybox.so.$BB_VER"
256 chmod a+x "$sharedlib_dir/libbusybox.so.$BB_VER"
257 echo "libbusybox: $sharedlib_dir/libbusybox.so.$BB_VER"
260 if test "$CONFIG_FEATURE_SHARED_BUSYBOX" = y; then
261 EXE="$sharedlib_dir/busybox_unstripped"
262 try $CC $CFLAGS $LDFLAGS \
267 $START_GROUP $O_FILES $END_GROUP \
268 -L"$sharedlib_dir" -lbusybox \
272 echo "Linking $EXE failed"
276 $STRIP -s --remove-section=.note --remove-section=.comment $EXE -o "$sharedlib_dir/busybox"
277 echo "busybox linked against libbusybox: $sharedlib_dir/busybox"
280 if test "$CONFIG_FEATURE_INDIVIDUAL" = y; then
281 echo "Linking individual applets against libbusybox (see $sharedlib_dir/*)"
282 gcc -DNAME_MAIN -E -include include/autoconf.h include/applets.h \
286 while read name main junk; do
289 void lbb_prepare(const char *applet, char **argv);
290 int $main(int argc, char **argv);
292 int main(int argc, char **argv)
294 lbb_prepare(\"$name\", argv);
295 return $main(argc, argv);
297 " >"$sharedlib_dir/applet.c"
299 EXE="$sharedlib_dir/$name"
300 try $CC $CFLAGS $LDFLAGS "$sharedlib_dir/applet.c" \
305 -L"$sharedlib_dir" -lbusybox \
308 echo "Linking $EXE failed"
312 rm -- "$sharedlib_dir/applet.c" $EXE.out
313 $STRIP -s --remove-section=.note --remove-section=.comment $EXE
314 # Let user see that we do something - list the names of created binaries:
320 # libbusybox.so is needed only for -lbusybox at link time,
321 # it is not needed at runtime. Deleting to reduce confusion.
322 rm "$sharedlib_dir"/libbusybox.so 2>/dev/null
323 exit 0 # or else we may confuse make