| 1 | #!/bin/sh
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| 2 |
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| 3 | debug=false
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| 4 |
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| 5 | # Linker flags used:
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| 6 | #
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| 7 | # Informational:
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| 8 | # --warn-common
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| 9 | # -Map $EXE.map
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| 10 | # --verbose
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| 11 | #
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| 12 | # Optimizations:
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| 13 | # --sort-common reduces padding
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| 14 | # --sort-section alignment reduces padding
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| 15 | # --gc-sections throws out unused sections,
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| 16 | # does not work for shared libs
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| 17 | # -On Not used, maybe useful?
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| 18 | #
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| 19 | # List of files to link:
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| 20 | # $l_list == --start-group -llib1 -llib2 --end-group
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| 21 | # --start-group $O_FILES $A_FILES --end-group
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| 22 | #
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| 23 | # Shared library link:
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| 24 | # -shared self-explanatory
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| 25 | # -fPIC position-independent code
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| 26 | # --enable-new-dtags ?
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| 27 | # -z,combreloc ?
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| 28 | # -soname="libbusybox.so.$BB_VER"
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| 29 | # --undefined=lbb_main Seed name to start pulling from
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| 30 | # (otherwise we'll need --whole-archive)
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| 31 | # -static Not used, but may be useful! manpage:
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| 32 | # "... This option can be used with -shared.
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| 33 | # Doing so means that a shared library
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| 34 | # is being created but that all of the library's
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| 35 | # external references must be resolved by pulling
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| 36 | # in entries from static libraries."
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| 37 |
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| 38 |
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| 39 | try() {
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| 40 | printf "%s\n" "Output of:" >$EXE.out
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| 41 | printf "%s\n" "$*" >>$EXE.out
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| 42 | printf "%s\n" "==========" >>$EXE.out
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| 43 | $debug && echo "Trying: $*"
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| 44 | $@ >>$EXE.out 2>&1
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| 45 | return $?
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| 46 | }
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| 47 |
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| 48 | check_cc() {
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| 49 | local tempname="$(mktemp)"
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| 50 | local r
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| 51 | echo "int main(int argc,char**argv){return argv?argc:0;}" >"$tempname".c
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| 52 | # Can use "-o /dev/null", but older gcc tend to *unlink it* on failure! :(
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| 53 | # Was using "-xc /dev/null", but we need a valid C program.
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| 54 | # "eval" may be needed if CFLAGS can contain
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| 55 | # '... -D"BB_VER=KBUILD_STR(1.N.M)" ...'
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| 56 | # and we need shell to process quotes!
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| 57 | $CC $CFLAGS $LDFLAGS $1 "$tempname".c -o "$tempname" >/dev/null 2>&1
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| 58 | r=$?
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| 59 | rm -f "$tempname" "$tempname".c "$tempname".o
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| 60 | return $r
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| 61 | }
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| 62 |
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| 63 | check_libc_is_glibc() {
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| 64 | local tempname="$(mktemp)"
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| 65 | local r
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| 66 | echo "\
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| 67 | #include <stdlib.h>
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| 68 | /* Apparently uclibc defines __GLIBC__ (compat trick?). Oh well. */
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| 69 | #if defined(__GLIBC__) && !defined(__UCLIBC__)
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| 70 | syntax error here
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| 71 | #endif
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| 72 | " >"$tempname".c
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| 73 | ! $CC $CFLAGS "$tempname".c -c -o "$tempname".o >/dev/null 2>&1
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| 74 | r=$?
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| 75 | rm -f "$tempname" "$tempname".c "$tempname".o
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| 76 | return $r
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| 77 | }
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| 78 |
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| 79 | EXE="$1"
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| 80 | CC="$2"
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| 81 | CFLAGS="$3"
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| 82 | LDFLAGS="$4"
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| 83 | O_FILES="$5"
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| 84 | A_FILES="$6"
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| 85 | LDLIBS="$7"
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| 86 |
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| 87 | # The --sort-section option is not supported by older versions of ld
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| 88 | SORT_SECTION="-Wl,--sort-section,alignment"
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| 89 | if ! check_cc "-Wl,--sort-section,alignment"; then
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| 90 | echo "Your linker does not support --sort-section,alignment"
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| 91 | SORT_SECTION=""
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| 92 | fi
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| 93 |
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| 94 | START_GROUP="-Wl,--start-group"
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| 95 | END_GROUP="-Wl,--end-group"
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| 96 | INFO_OPTS="-Wl,--warn-common -Wl,-Map,$EXE.map -Wl,--verbose"
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| 97 |
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| 98 | # gold may not support --sort-common (yet)
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| 99 | SORT_COMMON="-Wl,--sort-common"
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| 100 | if ! check_cc "-Wl,--sort-common"; then
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| 101 | echo "Your linker does not support --sort-common"
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| 102 | SORT_COMMON=""
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| 103 | fi
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| 104 |
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| 105 | # Static linking against glibc produces buggy executables
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| 106 | # (glibc does not cope well with ld --gc-sections).
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| 107 | # See sources.redhat.com/bugzilla/show_bug.cgi?id=3400
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| 108 | # Note that glibc is unsuitable for static linking anyway.
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| 109 | # We are removing -Wl,--gc-sections from link command line.
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| 110 | GC_SECTIONS="-Wl,--gc-sections"
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| 111 | if (. ./.config && test x"$CONFIG_STATIC" = x"y") then
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| 112 | if check_libc_is_glibc; then
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| 113 | echo "Static linking against glibc, can't use --gc-sections"
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| 114 | GC_SECTIONS=""
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| 115 | fi
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| 116 | fi
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| 117 | # The --gc-sections option is not supported by older versions of ld
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| 118 | if test -n "$GC_SECTIONS"; then
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| 119 | if ! check_cc "$GC_SECTIONS"; then
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| 120 | echo "Your linker does not support $GC_SECTIONS"
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| 121 | GC_SECTIONS=""
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| 122 | fi
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| 123 | fi
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| 124 |
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| 125 | # Sanitize lib list (dups, extra spaces etc)
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| 126 | LDLIBS=`echo "$LDLIBS" | xargs -n1 | sort | uniq | xargs`
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| 127 |
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| 128 | # First link with all libs. If it fails, bail out
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| 129 | echo "Trying libraries: $LDLIBS"
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| 130 | # "lib1 lib2 lib3" -> "-llib1 -llib2 -llib3"
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| 131 | l_list=`echo " $LDLIBS " | sed -e 's: \([^- ][^ ]*\): -l\1:g'`
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| 132 | test "x$l_list" != "x" && l_list="$START_GROUP $l_list $END_GROUP"
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| 133 | try $CC $CFLAGS $LDFLAGS \
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| 134 | -o $EXE \
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| 135 | $SORT_COMMON \
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| 136 | $SORT_SECTION \
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| 137 | $GC_SECTIONS \
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| 138 | $START_GROUP $O_FILES $A_FILES $END_GROUP \
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| 139 | $l_list \
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| 140 | || {
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| 141 | echo "Failed: $l_list"
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| 142 | cat $EXE.out
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| 143 | echo 'Note: if build needs additional libraries, put them in CONFIG_EXTRA_LDLIBS.'
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| 144 | echo 'Example: CONFIG_EXTRA_LDLIBS="pthread dl tirpc audit pam"'
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| 145 | exit 1
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| 146 | }
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| 147 |
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| 148 | # Now try to remove each lib and build without it.
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| 149 | # Stop when no lib can be removed.
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| 150 | while test "$LDLIBS"; do
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| 151 | $debug && echo "Trying libraries: $LDLIBS"
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| 152 | all_needed=true
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| 153 | last_needed=false
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| 154 | for one in $LDLIBS; do
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| 155 | without_one=`echo " $LDLIBS " | sed "s/ $one / /g" | xargs`
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| 156 | # "lib1 lib2 lib3" -> "-llib1 -llib2 -llib3"
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| 157 | l_list=`echo " $without_one " | sed -e 's: \([^- ][^ ]*\): -l\1:g'`
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| 158 | test x"$l_list" != x"" && l_list="$START_GROUP $l_list $END_GROUP"
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| 159 | $debug && echo "Trying -l options: '$l_list'"
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| 160 | try $CC $CFLAGS $LDFLAGS \
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| 161 | -o $EXE \
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| 162 | $SORT_COMMON \
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| 163 | $SORT_SECTION \
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| 164 | $GC_SECTIONS \
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| 165 | $START_GROUP $O_FILES $A_FILES $END_GROUP \
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| 166 | $l_list
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| 167 | if test $? = 0; then
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| 168 | echo " Library $one is not needed, excluding it"
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| 169 | LDLIBS="$without_one"
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| 170 | all_needed=false
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| 171 | last_needed=false
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| 172 | else
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| 173 | echo " Library $one is needed, can't exclude it (yet)"
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| 174 | last_needed=true
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| 175 | fi
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| 176 | done
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| 177 | # All libs were needed, can't remove any
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| 178 | $all_needed && break
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| 179 | # Optimization: was the last tried lib needed?
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| 180 | if $last_needed; then
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| 181 | # Was it the only one lib left? Don't test again then.
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| 182 | { echo "$LDLIBS" | grep -q ' '; } || break
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| 183 | fi
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| 184 | done
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| 185 |
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| 186 | # Make the binary with final, minimal list of libs
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| 187 | echo "Final link with: ${LDLIBS:-<none>}"
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| 188 | l_list=`echo " $LDLIBS " | sed -e 's: \([^- ][^ ]*\): -l\1:g'`
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| 189 | test "x$l_list" != "x" && l_list="$START_GROUP $l_list $END_GROUP"
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| 190 | # --verbose gives us gobs of info to stdout (e.g. linker script used)
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| 191 | if ! test -f busybox_ldscript; then
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| 192 | try $CC $CFLAGS $LDFLAGS \
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| 193 | -o $EXE \
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| 194 | $SORT_COMMON \
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| 195 | $SORT_SECTION \
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| 196 | $GC_SECTIONS \
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| 197 | $START_GROUP $O_FILES $A_FILES $END_GROUP \
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| 198 | $l_list \
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| 199 | $INFO_OPTS \
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| 200 | || {
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| 201 | cat $EXE.out
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| 202 | exit 1
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| 203 | }
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| 204 | else
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| 205 | echo "Custom linker script 'busybox_ldscript' found, using it"
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| 206 | # Add SORT_BY_ALIGNMENT to linker script (found in $EXE.out):
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| 207 | # .rodata : { *(.rodata SORT_BY_ALIGNMENT(.rodata.*) .gnu.linkonce.r.*) }
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| 208 | # *(.data SORT_BY_ALIGNMENT(.data.*) .gnu.linkonce.d.*)
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| 209 | # *(.bss SORT_BY_ALIGNMENT(.bss.*) .gnu.linkonce.b.*)
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| 210 | # This will eliminate most of the padding (~3kb).
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| 211 | # Hmm, "ld --sort-section alignment" should do it too.
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| 212 | #
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| 213 | # There is a ld hack which is meant to decrease disk usage
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| 214 | # at the cost of more RAM usage (??!!) in standard ld script:
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| 215 | # /* Adjust the address for the data segment. We want to adjust up to
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| 216 | # the same address within the page on the next page up. */
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| 217 | # . = ALIGN (0x1000) - ((0x1000 - .) & (0x1000 - 1)); . = DATA_SEGMENT_ALIGN (0x1000, 0x1000);
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| 218 | # Replace it with:
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| 219 | # . = ALIGN (0x1000); . = DATA_SEGMENT_ALIGN (0x1000, 0x1000);
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| 220 | # to unconditionally align .data to the next page boundary,
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| 221 | # instead of "next page, plus current offset in this page"
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| 222 | try $CC $CFLAGS $LDFLAGS \
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| 223 | -o $EXE \
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| 224 | $SORT_COMMON \
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| 225 | $SORT_SECTION \
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| 226 | $GC_SECTIONS \
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| 227 | -Wl,-T,busybox_ldscript \
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| 228 | $START_GROUP $O_FILES $A_FILES $END_GROUP \
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| 229 | $l_list \
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| 230 | $INFO_OPTS \
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| 231 | || {
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| 232 | cat $EXE.out
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| 233 | exit 1
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| 234 | }
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| 235 | fi
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| 236 |
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| 237 | . ./.config
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| 238 |
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| 239 | sharedlib_dir="0_lib"
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| 240 |
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| 241 | if test "$CONFIG_BUILD_LIBBUSYBOX" = y; then
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| 242 | mkdir "$sharedlib_dir" 2>/dev/null
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| 243 | test -d "$sharedlib_dir" || {
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| 244 | echo "Cannot make directory $sharedlib_dir"
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| 245 | exit 1
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| 246 | }
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| 247 | ln -s "libbusybox.so.$BB_VER" "$sharedlib_dir"/libbusybox.so 2>/dev/null
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| 248 |
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| 249 | EXE="$sharedlib_dir/libbusybox.so.${BB_VER}_unstripped"
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| 250 | try $CC $CFLAGS $LDFLAGS \
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| 251 | -o $EXE \
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| 252 | -shared -fPIC \
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| 253 | -Wl,--enable-new-dtags \
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| 254 | -Wl,-z,combreloc \
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| 255 | -Wl,-soname="libbusybox.so.$BB_VER" \
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| 256 | -Wl,--undefined=lbb_main \
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| 257 | $SORT_COMMON \
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| 258 | $SORT_SECTION \
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| 259 | $START_GROUP $A_FILES $END_GROUP \
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| 260 | $l_list \
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| 261 | $INFO_OPTS \
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| 262 | || {
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| 263 | echo "Linking $EXE failed"
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| 264 | cat $EXE.out
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| 265 | exit 1
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| 266 | }
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| 267 | $STRIP -s --remove-section=.note --remove-section=.comment $EXE -o "$sharedlib_dir/libbusybox.so.$BB_VER"
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| 268 | chmod a+x "$sharedlib_dir/libbusybox.so.$BB_VER"
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| 269 | echo "libbusybox: $sharedlib_dir/libbusybox.so.$BB_VER"
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| 270 | fi
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| 271 |
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| 272 | if test "$CONFIG_FEATURE_SHARED_BUSYBOX" = y; then
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| 273 | EXE="$sharedlib_dir/busybox_unstripped"
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| 274 | try $CC $CFLAGS $LDFLAGS \
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| 275 | -o $EXE \
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| 276 | $SORT_COMMON \
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| 277 | $SORT_SECTION \
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| 278 | $GC_SECTIONS \
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| 279 | $START_GROUP $O_FILES $END_GROUP \
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| 280 | -L"$sharedlib_dir" -lbusybox \
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| 281 | $l_list \
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| 282 | $INFO_OPTS \
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| 283 | || {
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| 284 | echo "Linking $EXE failed"
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| 285 | cat $EXE.out
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| 286 | exit 1
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| 287 | }
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| 288 | $STRIP -s --remove-section=.note --remove-section=.comment $EXE -o "$sharedlib_dir/busybox"
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| 289 | echo "busybox linked against libbusybox: $sharedlib_dir/busybox"
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| 290 | fi
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| 291 |
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| 292 | if test "$CONFIG_FEATURE_INDIVIDUAL" = y; then
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| 293 | echo "Linking individual applets against libbusybox (see $sharedlib_dir/*)"
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| 294 | gcc -DNAME_MAIN -E -include include/autoconf.h include/applets.h \
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| 295 | | grep -v "^#" \
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| 296 | | grep -v "^ *$" \
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| 297 | > applet_lst.tmp
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| 298 | while read name main junk; do
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| 299 |
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| 300 | echo "\
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| 301 | void lbb_prepare(const char *applet, char **argv);
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| 302 | int $main(int argc, char **argv);
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| 303 |
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| 304 | int main(int argc, char **argv)
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| 305 | {
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| 306 | lbb_prepare(\"$name\", argv);
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| 307 | return $main(argc, argv);
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| 308 | }
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| 309 | " >"$sharedlib_dir/applet.c"
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| 310 |
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| 311 | EXE="$sharedlib_dir/$name"
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| 312 | try $CC $CFLAGS $LDFLAGS "$sharedlib_dir/applet.c" \
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| 313 | -o $EXE \
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| 314 | $SORT_COMMON \
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| 315 | $SORT_SECTION \
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| 316 | $GC_SECTIONS \
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| 317 | -L"$sharedlib_dir" -lbusybox \
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| 318 | -Wl,--warn-common \
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| 319 | || {
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| 320 | echo "Linking $EXE failed"
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| 321 | cat $EXE.out
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| 322 | exit 1
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| 323 | }
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| 324 | rm -- "$sharedlib_dir/applet.c" $EXE.out
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| 325 | $STRIP -s --remove-section=.note --remove-section=.comment $EXE
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| 326 | # Let user see that we do something - list the names of created binaries:
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| 327 | echo "$EXE"
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| 328 |
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| 329 | done <applet_lst.tmp
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| 330 | fi
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| 331 |
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| 332 | # libbusybox.so is needed only for -lbusybox at link time,
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| 333 | # it is not needed at runtime. Deleting to reduce confusion.
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| 334 | rm "$sharedlib_dir"/libbusybox.so 2>/dev/null
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| 335 | exit 0 # or else we may confuse make
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