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="/tmp/temp.$$.$RANDOM"
50 # Can use "-o /dev/null", but older gcc tend to *unlink it* on failure! :(
51 # "-xc": C language. "/dev/null" is an empty source file.
52 if $CC $1 -shared -xc /dev/null -o "$tempname".o >/dev/null 2>&1; then
57 rm "$tempname".o 2>/dev/null
60 check_libc_is_glibc() {
61 local tempname="/tmp/temp.$$.$RANDOM"
64 /* Apparently uclibc defines __GLIBC__ (compat trick?). Oh well. */
65 #if defined(__GLIBC__) && !defined(__UCLIBC__)
69 if $CC "$tempname".c -c -o "$tempname".o >/dev/null 2>&1; then
74 rm "$tempname".c "$tempname".o 2>/dev/null
85 # The --sort-section option is not supported by older versions of ld
86 SORT_SECTION=`check_cc "-Wl,--sort-section,alignment" ""`
88 # gold may not support --sort-common (yet)
89 SORT_COMMON=`check_cc "-Wl,--sort-common" ""`
91 # Static linking against glibc produces buggy executables
92 # (glibc does not cope well with ld --gc-sections).
93 # See sources.redhat.com/bugzilla/show_bug.cgi?id=3400
94 # Note that glibc is unsuitable for static linking anyway.
95 # We are removing -Wl,--gc-sections from link command line.
98 if test x"$CONFIG_STATIC" = x"y"; then
99 check_libc_is_glibc "" "-Wl,--gc-sections"
101 echo "-Wl,--gc-sections"
105 # The --gc-sections option is not supported by older versions of ld
106 if test -n "$GC_SECTIONS"; then
107 GC_SECTIONS=`check_cc "$GC_SECTIONS" ""`
110 # Sanitize lib list (dups, extra spaces etc)
111 LDLIBS=`echo "$LDLIBS" | xargs -n1 | sort | uniq | xargs`
113 # First link with all libs. If it fails, bail out
114 echo "Trying libraries: $LDLIBS"
115 # "lib1 lib2 lib3" -> "-llib1 -llib2 -llib3"
116 l_list=`echo "$LDLIBS" | sed -e 's/ / -l/g' -e 's/^/-l/' -e 's/^-l$//'`
117 test "x$l_list" != "x" && l_list="-Wl,--start-group $l_list -Wl,--end-group"
118 try $CC $CFLAGS $LDFLAGS \
123 -Wl,--start-group $O_FILES $A_FILES -Wl,--end-group \
126 echo "Failed: $l_list"
131 # Now try to remove each lib and build without it.
132 # Stop when no lib can be removed.
133 while test "$LDLIBS"; do
134 $debug && echo "Trying libraries: $LDLIBS"
137 for one in $LDLIBS; do
138 without_one=`echo " $LDLIBS " | sed "s/ $one / /g" | xargs`
139 # "lib1 lib2 lib3" -> "-llib1 -llib2 -llib3"
140 l_list=`echo "$without_one" | sed -e 's/ / -l/g' -e 's/^/-l/' -e 's/^-l$//'`
141 test x"$l_list" != x"" && l_list="-Wl,--start-group $l_list -Wl,--end-group"
142 $debug && echo "Trying -l options: '$l_list'"
143 try $CC $CFLAGS $LDFLAGS \
148 -Wl,--start-group $O_FILES $A_FILES -Wl,--end-group \
151 echo " Library $one is not needed, excluding it"
152 LDLIBS="$without_one"
156 echo " Library $one is needed, can't exclude it (yet)"
160 # All libs were needed, can't remove any
162 # Optimization: was the last tried lib needed?
163 if $last_needed; then
164 # Was it the only one lib left? Don't test again then.
165 { echo "$LDLIBS" | grep -q ' '; } || break
169 # Make the binary with final, minimal list of libs
170 echo "Final link with: ${LDLIBS:-<none>}"
171 l_list=`echo "$LDLIBS" | sed -e 's/ / -l/g' -e 's/^/-l/' -e 's/^-l$//'`
172 test "x$l_list" != "x" && l_list="-Wl,--start-group $l_list -Wl,--end-group"
173 # --verbose gives us gobs of info to stdout (e.g. linker script used)
174 if ! test -f busybox_ldscript; then
175 try $CC $CFLAGS $LDFLAGS \
180 -Wl,--start-group $O_FILES $A_FILES -Wl,--end-group \
190 echo "Custom linker script 'busybox_ldscript' found, using it"
191 # Add SORT_BY_ALIGNMENT to linker script (found in $EXE.out):
192 # .rodata : { *(.rodata SORT_BY_ALIGNMENT(.rodata.*) .gnu.linkonce.r.*) }
193 # *(.data SORT_BY_ALIGNMENT(.data.*) .gnu.linkonce.d.*)
194 # *(.bss SORT_BY_ALIGNMENT(.bss.*) .gnu.linkonce.b.*)
195 # This will eliminate most of the padding (~3kb).
196 # Hmm, "ld --sort-section alignment" should do it too.
197 try $CC $CFLAGS $LDFLAGS \
202 -Wl,-T,busybox_ldscript \
203 -Wl,--start-group $O_FILES $A_FILES -Wl,--end-group \
216 sharedlib_dir="0_lib"
218 if test "$CONFIG_BUILD_LIBBUSYBOX" = y; then
219 mkdir "$sharedlib_dir" 2>/dev/null
220 test -d "$sharedlib_dir" || {
221 echo "Cannot make directory $sharedlib_dir"
224 ln -s "libbusybox.so.$BB_VER" "$sharedlib_dir"/libbusybox.so 2>/dev/null
226 EXE="$sharedlib_dir/libbusybox.so.${BB_VER}_unstripped"
227 try $CC $CFLAGS $LDFLAGS \
230 -Wl,--enable-new-dtags \
232 -Wl,-soname="libbusybox.so.$BB_VER" \
233 -Wl,--undefined=lbb_main \
236 -Wl,--start-group $A_FILES -Wl,--end-group \
242 echo "Linking $EXE failed"
246 $STRIP -s --remove-section=.note --remove-section=.comment $EXE -o "$sharedlib_dir/libbusybox.so.$BB_VER"
247 chmod a+x "$sharedlib_dir/libbusybox.so.$BB_VER"
248 echo "libbusybox: $sharedlib_dir/libbusybox.so.$BB_VER"
251 if test "$CONFIG_FEATURE_SHARED_BUSYBOX" = y; then
252 EXE="$sharedlib_dir/busybox_unstripped"
253 try $CC $CFLAGS $LDFLAGS \
258 -Wl,--start-group $O_FILES -Wl,--end-group \
259 -L"$sharedlib_dir" -lbusybox \
264 echo "Linking $EXE failed"
268 $STRIP -s --remove-section=.note --remove-section=.comment $EXE -o "$sharedlib_dir/busybox"
269 echo "busybox linked against libbusybox: $sharedlib_dir/busybox"
272 if test "$CONFIG_FEATURE_INDIVIDUAL" = y; then
273 echo "Linking individual applets against libbusybox (see $sharedlib_dir/*)"
274 gcc -DNAME_MAIN_CNAME -E -include include/autoconf.h include/applets.h \
278 while read name main junk; do
281 void lbb_prepare(const char *applet, char **argv);
282 int $main(int argc, char **argv);
284 int main(int argc, char **argv)
286 lbb_prepare(\"$name\", argv);
287 return $main(argc, argv);
289 " >"$sharedlib_dir/applet.c"
291 EXE="$sharedlib_dir/$name"
292 try $CC $CFLAGS $LDFLAGS "$sharedlib_dir/applet.c" \
297 -L"$sharedlib_dir" -lbusybox \
300 echo "Linking $EXE failed"
304 rm -- "$sharedlib_dir/applet.c" $EXE.out
305 $STRIP -s --remove-section=.note --remove-section=.comment $EXE
310 # libbusybox.so is needed only for -lbusybox at link time,
311 # it is not needed at runtime. Deleting to reduce confusion.
312 rm "$sharedlib_dir"/libbusybox.so 2>/dev/null
313 exit 0 # or else we may confuse make