scripts/trylink

   1 #!/bin/sh
   2
   3 debug=false
   4
   5 # Linker flags used:
   6 #
   7 # Informational:
   8 # --warn-common
   9 # -Map $EXE.map
  10 # --verbose
  11 #
  12 # Optimizations:
  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 # -O                            Not used, maybe useful?
  18 #
  19 # List of files to link:
  20 # $l_list                       == --start-group -llib1 -llib2 --end-group
  21 # --start-group $O_FILES $A_FILES --end-group
  22 # or for shlib:
  23 # --start-group --whole-archive $A_FILES --no-whole-archive --end-group
  24 # otherwise we don't pull in all parts of *.a files. Now we pull in too much.
  25 # FIXME: make it work without --whole-archive, or better, with --gc-sections.
  26 #
  27 # Shared library link:
  28 # -shared                       self-explanatory
  29 # -fPIC                         position-independent code
  30 # -Wl,--enable-new-dtags        ?
  31 # -Wl,-z,combreloc              ?
  32 # -Wl,-soname="libbusybox.so.$BB_VER"
  33 # -static                       Not used, but may be useful! manpage:
  34 #                               "... This option can be used with -shared.
  35 #                               Doing so means that a shared library
  36 #                               is being created but that all of the library's
  37 #                               external references must be resolved by pulling
  38 #                               in entries from static libraries."
  39
  40
  41 try() {
  42     printf "%s\n" "Output of:" >$EXE.out
  43     printf "%s\n" "$*" >>$EXE.out
  44     printf "%s\n" "==========" >>$EXE.out
  45     $debug && echo "Trying: $*"
  46     "$@" >>$EXE.out 2>&1
  47     exitcode=$?
  48     return $exitcode
  49 }
  50
  51 EXE="$1"
  52 CC="$2"
  53 LDFLAGS="$3"
  54 O_FILES="$4"
  55 A_FILES="$5"
  56 LDLIBS="$6"
  57
  58 # Sanitize lib list (dups, extra spaces etc)
  59 LDLIBS=`echo "$LDLIBS" | xargs -n1 | sort | uniq | xargs`
  60
  61 # First link with all libs. If it fails, bail out
  62 echo "Trying libraries: $LDLIBS"
  63 # "lib1 lib2 lib3" -> "-llib1 -llib2 -llib3"
  64 l_list=`echo "$LDLIBS" | sed -e 's/ / -l/g' -e 's/^/-l/' -e 's/^-l$//'`
  65 test "x$l_list" != "x" && l_list="-Wl,--start-group $l_list -Wl,--end-group"
  66 try $CC $LDFLAGS \
  67         -o $EXE \
  68         -Wl,--sort-common \
  69         -Wl,--sort-section -Wl,alignment \
  70         -Wl,--gc-sections \
  71         -Wl,--start-group $O_FILES $A_FILES -Wl,--end-group \
  72         $l_list \
  73 || {
  74     echo "Failed: $* $l_list"
  75     cat $EXE.out
  76     exit 1
  77 }
  78
  79 # Now try to remove each lib and build without it.
  80 # Stop when no lib can be removed.
  81 while test "$LDLIBS"; do
  82     $debug && echo "Trying libraries: $LDLIBS"
  83     all_needed=true
  84     for one in $LDLIBS; do
  85         without_one=`echo " $LDLIBS " | sed "s/ $one / /g" | xargs`
  86         # "lib1 lib2 lib3" -> "-llib1 -llib2 -llib3"
  87         l_list=`echo "$without_one" | sed -e 's/ / -l/g' -e 's/^/-l/' -e 's/^-l$//'`
  88         test "x$l_list" != "x" && l_list="-Wl,--start-group $l_list -Wl,--end-group"
  89         $debug && echo "Trying -l options: '$l_list'"
  90         try $CC $LDFLAGS \
  91                 -o $EXE \
  92                 -Wl,--sort-common \
  93                 -Wl,--sort-section -Wl,alignment \
  94                 -Wl,--gc-sections \
  95                 -Wl,--start-group $O_FILES $A_FILES -Wl,--end-group \
  96                 $l_list
  97         if test $? = 0; then
  98             echo "Library $one is not needed"
  99             LDLIBS="$without_one"
 100             all_needed=false
 101         else
 102             echo "Library $one is needed"
 103         fi
 104     done
 105     # All libs were needed, can't remove any
 106     $all_needed && break
 107     # If there is no space char, the list has just one lib.
 108     # I'm not sure that in this case lib really is 100% needed.
 109     # Let's try linking without it anyway... thus commented out.
 110     #{ echo "$LDLIBS" | grep -q ' '; } || break
 111 done
 112
 113 # Make the binary with final, minimal list of libs
 114 echo "Final link with: $LDLIBS"
 115 l_list=`echo "$LDLIBS" | sed -e 's/ / -l/g' -e 's/^/-l/' -e 's/^-l$//'`
 116 test "x$l_list" != "x" && l_list="-Wl,--start-group $l_list -Wl,--end-group"
 117 # --verbose gives us gobs of info to stdout (e.g. linker script used)
 118 if ! test -f busybox_ldscript; then
 119     try $CC $LDFLAGS \
 120             -o $EXE \
 121             -Wl,--sort-common \
 122             -Wl,--sort-section -Wl,alignment \
 123             -Wl,--gc-sections \
 124             -Wl,--start-group $O_FILES $A_FILES -Wl,--end-group \
 125             $l_list \
 126             -Wl,--warn-common \
 127             -Wl,-Map -Wl,$EXE.map \
 128             -Wl,--verbose \
 129     || {
 130         cat $EXE.out
 131         exit 1
 132     }
 133 else
 134     echo "Custom linker script 'busybox_ldscript' found, using it"
 135     # Add SORT_BY_ALIGNMENT to linker script (found in $EXE.out):
 136     #  .rodata         : { *(.rodata SORT_BY_ALIGNMENT(.rodata.*) .gnu.linkonce.r.*) }
 137     #  *(.data SORT_BY_ALIGNMENT(.data.*) .gnu.linkonce.d.*)
 138     #  *(.bss SORT_BY_ALIGNMENT(.bss.*) .gnu.linkonce.b.*)
 139     # This will eliminate most of the padding (~3kb).
 140     # Hmm, "ld --sort-section alignment" should do it too.
 141     try $CC $LDFLAGS \
 142             -o $EXE \
 143             -Wl,--sort-common \
 144             -Wl,--sort-section -Wl,alignment \
 145             -Wl,--gc-sections \
 146             -Wl,-T -Wl,busybox_ldscript \
 147             -Wl,--start-group $O_FILES $A_FILES -Wl,--end-group \
 148             $l_list \
 149             -Wl,--warn-common \
 150             -Wl,-Map -Wl,$EXE.map \
 151             -Wl,--verbose \
 152     || {
 153         cat $EXE.out
 154         exit 1
 155     }
 156 fi
 157
 158 . .config
 159
 160 sharedlib_dir="0_lib"
 161
 162 if test "$CONFIG_BUILD_LIBBUSYBOX" = y; then
 163     mkdir "$sharedlib_dir" 2>/dev/null
 164     test -d "$sharedlib_dir" || {
 165         echo "Cannot make directory $sharedlib_dir"
 166         exit 1
 167     }
 168     ln -s "libbusybox.so.$BB_VER" "$sharedlib_dir"/libbusybox.so 2>/dev/null
 169
 170     EXE="$sharedlib_dir/libbusybox.so.${BB_VER}_unstripped"
 171     try $CC $LDFLAGS \
 172             -o $EXE \
 173             -shared -fPIC \
 174             -Wl,--enable-new-dtags \
 175             -Wl,-z,combreloc \
 176             -Wl,-soname="libbusybox.so.$BB_VER" \
 177             -Wl,--sort-common \
 178             -Wl,--sort-section -Wl,alignment \
 179             -Wl,--start-group -Wl,--whole-archive $A_FILES -Wl,--no-whole-archive -Wl,--end-group \
 180             $l_list \
 181             -Wl,--warn-common \
 182             -Wl,-Map -Wl,$EXE.map \
 183             -Wl,--verbose \
 184     || {
 185         echo "Linking $EXE failed"
 186         cat $EXE.out
 187         exit 1
 188     }
 189     strip -s --remove-section=.note --remove-section=.comment $EXE -o "$sharedlib_dir/libbusybox.so.$BB_VER"
 190     chmod a+x "$sharedlib_dir/libbusybox.so.$BB_VER"
 191     echo "libbusybox: $sharedlib_dir/libbusybox.so.$BB_VER"
 192 fi
 193
 194 if test "$CONFIG_FEATURE_SHARED_BUSYBOX" = y; then
 195     EXE="$sharedlib_dir/busybox_unstripped"
 196     try $CC $LDFLAGS \
 197             -o $EXE \
 198             -Wl,--sort-common \
 199             -Wl,--sort-section -Wl,alignment \
 200             -Wl,--gc-sections \
 201             -Wl,--start-group $O_FILES -Wl,--end-group \
 202             -L"$sharedlib_dir" -lbusybox \
 203             -Wl,--warn-common \
 204             -Wl,-Map -Wl,$EXE.map \
 205             -Wl,--verbose \
 206     || {
 207         echo "Linking $EXE failed"
 208         cat $EXE.out
 209         exit 1
 210     }
 211     strip -s --remove-section=.note --remove-section=.comment $EXE -o "$sharedlib_dir/busybox"
 212     echo "busybox linked against libbusybox: $sharedlib_dir/busybox"
 213 fi
 214
 215 if test "$CONFIG_FEATURE_INDIVIDUAL" = y; then
 216     echo "Linking individual applets against libbusybox (see $sharedlib_dir/*)"
 217     gcc -DNAME_MAIN_CNAME -E -include include/autoconf.h include/applets.h \
 218     | grep -v "^#" \
 219     | grep -v "^$" \
 220     > applet_lst.tmp
 221     while read name main junk; do
 222
 223         echo "\
 224 void bbox_prepare_main(char **argv);
 225 int $main(int argc, char **argv);
 226
 227 const char *applet_name = \"$name\";
 228
 229 int main(int argc, char **argv)
 230 {
 231         bbox_prepare_main(argv);
 232         return $main(argc, argv);
 233 }
 234 " >"$sharedlib_dir/applet.c"
 235
 236         EXE="$sharedlib_dir/$name"
 237         try $CC $LDFLAGS "$sharedlib_dir/applet.c" \
 238                 -o $EXE \
 239                 -Wl,--sort-common \
 240                 -Wl,--sort-section -Wl,alignment \
 241                 -Wl,--gc-sections \
 242                 -L"$sharedlib_dir" -lbusybox \
 243                 -Wl,--warn-common \
 244         || {
 245             echo "Linking $EXE failed"
 246             cat $EXE.out
 247             exit 1
 248         }
 249         rm -- "$sharedlib_dir/applet.c" $EXE.out
 250         strip -s --remove-section=.note --remove-section=.comment $EXE
 251
 252     done <applet_lst.tmp
 253 fi
 254
 255 # libbusybox.so is needed only for -lbusybox at link time,
 256 # it is not needed at runtime. Deleting to reduce confusion.
 257 rm "$sharedlib_dir"/libbusybox.so 2>/dev/null
 258 exit 0 # or else we may confuse make