2 files changed, 191 insertions, 0 deletions

diff --git a/scripts/generate_BUFSIZ.sh b/scripts/generate_BUFSIZ.sh
new file mode 100755
index 000000000..844261906
--- /dev/null
+++ b/scripts/generate_BUFSIZ.sh
@@ -0,0 +1,181 @@
+#!/bin/sh
+# Called from top-level directory a-la
+#
+# scripts/generate_BUFSIZ.sh include/common_bufsiz.h
+
+. ./.config || exit 1
+
+debug=false
+#debug=true
+
+postcompile=false
+test x"$1" = x"--post" && { postcompile=true; shift; }
+
+common_bufsiz_h=$1
+
+test x"$NM" = x"" && NM="${CONFIG_CROSS_COMPILER_PREFIX}nm"
+test x"$CC" = x"" && CC="${CONFIG_CROSS_COMPILER_PREFIX}gcc"
+
+exitcmd="exit 0"
+
+regenerate() {
+        cat >"$1.$$"
+        test -f "$1" && diff "$1.$$" "$1" >/dev/null && rm "$1.$$" && return
+        mv "$1.$$" "$1"
+}
+
+generate_std_and_exit() {
+        $debug && echo "Configuring: bb_common_bufsiz1[] in bss"
+        {
+        echo "enum { COMMON_BUFSIZE = 1024 };"
+        echo "extern char bb_common_bufsiz1[];"
+        echo "#define setup_common_bufsiz() ((void)0)"
+        } | regenerate "$common_bufsiz_h"
+        echo "std" >"$common_bufsiz_h.method"
+        $exitcmd
+}
+
+generate_big_and_exit() {
+        $debug && echo "Configuring: bb_common_bufsiz1[] in _end[], COMMON_BUFSIZE = $1"
+        {
+        echo "enum { COMMON_BUFSIZE = $1 };"
+        echo "extern char _end[]; /* linker-provided label */"
+        echo "#define bb_common_bufsiz1 _end"
+        echo "#define setup_common_bufsiz() ((void)0)"
+        } | regenerate "$common_bufsiz_h"
+        echo "$2" >"$common_bufsiz_h.method"
+        $exitcmd
+}
+
+generate_1k_and_exit() {
+        generate_big_and_exit 1024 "1k"
+}
+
+
+generate_malloc_and_exit() {
+        $debug && echo "Configuring: bb_common_bufsiz1[] is malloced"
+        {
+        echo "enum { COMMON_BUFSIZE = 1024 };"
+        echo "extern char *const bb_common_bufsiz1;"
+        echo "void setup_common_bufsiz(void);"
+        } | regenerate "$common_bufsiz_h"
+        echo "malloc" >"$common_bufsiz_h.method"
+        $exitcmd
+}
+
+round_down_COMMON_BUFSIZE() {
+        COMMON_BUFSIZE=$(( ($1-32) & 0xfffffe0 ))
+        COMMON_BUFSIZE=$(( COMMON_BUFSIZE < 1024 ? 1024 : COMMON_BUFSIZE ))
+}
+
+# User does not want any funky stuff?
+test x"$CONFIG_FEATURE_USE_BSS_TAIL" = x"y" || generate_std_and_exit
+
+# The script is run two times: before compilation, when it needs to
+# (re)generate $common_bufsiz_h, and directly after successful build,
+# when it needs to assess whether the build is ok to use at all (not buggy),
+# and (re)generate $common_bufsiz_h for a future build.
+
+if $postcompile; then
+        # Postcompile needs to create/delete OK/FAIL files
+
+        test -f busybox_unstripped || exit 1
+        test -f "$common_bufsiz_h.method" || exit 1
+
+        # How the build was done?
+        method=`cat -- "$common_bufsiz_h.method"`
+
+        # Get _end address
+        END=`$NM busybox_unstripped | grep ' . _end$'| cut -d' ' -f1`
+        test x"$END" = x"" && generate_std_and_exit
+        $debug && echo "END:0x$END $((0x$END))"
+        END=$((0x$END))
+
+        # Get PAGE_SIZE
+        {
+        echo "#include <sys/user.h>"
+        echo "#if defined(PAGE_SIZE) && PAGE_SIZE > 0"
+        echo "char page_size[PAGE_SIZE];"
+        echo "#endif"
+        } >page_size_$$.c
+        $CC -c "page_size_$$.c" || exit 1
+        PAGE_SIZE=`$NM --size-sort "page_size_$$.o" | cut -d' ' -f1`
+        rm "page_size_$$.c" "page_size_$$.o"
+        test x"$PAGE_SIZE" = x"" && exit 1
+        $debug && echo "PAGE_SIZE:0x$PAGE_SIZE $((0x$PAGE_SIZE))"
+        PAGE_SIZE=$((0x$PAGE_SIZE))
+        test $PAGE_SIZE -lt 512 && exit 1
+
+        # How much space between _end[] and next page?
+        PAGE_MASK=$((PAGE_SIZE-1))
+        TAIL_SIZE=$(( (-END) & PAGE_MASK ))
+        $debug && echo "TAIL_SIZE:$TAIL_SIZE bytes"
+
+        if test x"$method" = x"1k" || test x"$method" = x"big"; then
+                if test $TAIL_SIZE -lt 1024; then
+                        # _end[] has no enough space for bb_common_bufsiz1[]
+                        echo "Warning! Space in _end[] is too small ($TAIL_SIZE bytes)!"
+                        echo "Rerun make to build a binary which doesn't use it!"
+                        rm -- "$common_bufsiz_h.1k.OK" 2>/dev/null
+                        { md5sum <.config | cut -d' ' -f1; stat -c "%Y" .config; } >"$common_bufsiz_h.1k.FAIL"
+                        rm busybox_unstripped busybox 2>/dev/null
+# Note: here we can do either a "malloc" or "std" build.
+# "malloc" gives a bit bigger code:
+#     text  bss filename
+#   804355 5385 busybox.std
+#   804618 4361 busybox.malloc
+# but may have a smaller .bss (not guaranteed!). Use "pmap -x" to verify.
+                        exitcmd="exit 1"
+                        generate_malloc_and_exit
+                else
+                        PREV_SIZE=1024
+                        test x"$method" = x"big" && PREV_SIZE=`cat -- "$common_bufsiz_h.1k.OK"`
+                        round_down_COMMON_BUFSIZE $PREV_SIZE
+                        PREV_BUFSIZE=$COMMON_BUFSIZE
+
+                        rm -- "$common_bufsiz_h.1k.FAIL" 2>/dev/null
+                        echo $TAIL_SIZE >"$common_bufsiz_h.1k.OK"
+                        round_down_COMMON_BUFSIZE $TAIL_SIZE
+                        # emit message only if COMMON_BUFSIZE is indeed larger
+                        test $COMMON_BUFSIZE -gt $PREV_BUFSIZE \
+                                && echo "Rerun make to use larger COMMON_BUFSIZE ($COMMON_BUFSIZE)"
+#TODO: test $PREV_BUFSIZE -lt $TAIL_SIZE && PANIC!!!
+#Code size with COMMON_BUFSIZE > 1024 may be bigger than code with COMMON_BUFSIZE = 1024!
+#(currently we just hope "-32 and round down to 32" saves us)
+
+                        test $COMMON_BUFSIZE = 1024 && generate_1k_and_exit
+                        generate_big_and_exit $COMMON_BUFSIZE "big"
+                fi
+        fi
+fi
+
+# Based on past success/fail of 1k build, decide next build type
+
+if test -f "$common_bufsiz_h.1k.OK"; then
+        # Previous build succeeded fitting 1k into _end[].
+        # Try bigger COMMON_BUFSIZE if possible.
+        TAIL_SIZE=`cat -- "$common_bufsiz_h.1k.OK"`
+        round_down_COMMON_BUFSIZE $TAIL_SIZE
+        test $COMMON_BUFSIZE = 1024 && generate_1k_and_exit
+        generate_big_and_exit $COMMON_BUFSIZE "big"
+fi
+
+if test -f "$common_bufsiz_h.1k.FAIL"; then
+        # Previous build FAILED to fit 1k into _end[].
+        # Was it with same .config?
+        oldcfg=`cat -- "$common_bufsiz_h.1k.FAIL"`
+        curcfg=`md5sum <.config | cut -d' ' -f1; stat -c "%Y" .config`
+        # If yes, then build a "malloced" version
+        if test x"$oldcfg" = x"$curcfg"; then
+                echo "Will not try 1k build, it failed before. Touch .config to override"
+# Note: here we can do either a "malloc" or "std" build.
+                generate_malloc_and_exit
+        fi
+        # else: try 1k version
+        echo "New .config, will try 1k build"
+        rm -- "$common_bufsiz_h.1k.FAIL"
+        generate_1k_and_exit
+fi
+
+# There was no 1k build yet. Try it.
+generate_1k_and_exit
diff --git a/scripts/trylink b/scripts/trylink
index 15435f009..129570a60 100755
--- a/scripts/trylink
+++ b/scripts/trylink
@@ -209,6 +209,16 @@ else
     #  *(.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 \