build system: FEATURE_LIBBUSYBOX_STATIC - try to pull libc/libm into libbusybox

It variously fails with different toolchains I tried...

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

2 files changed, 32 insertions, 29 deletions

diff --git a/Config.in b/Config.in
index cfb3aa0ee..82baed50a 100644
--- a/Config.in
+++ b/Config.in
@@ -386,29 +386,26 @@ config BUILD_LIBBUSYBOX
           Build a shared library libbusybox.so.N.N.N which contains all
           busybox code.
 
-          This feature allows every applet to be built as a tiny
-          separate executable. Enabling it for "one big busybox binary"
-          approach serves no purpose and increases code size.
-          You should almost certainly say "no" to this.
-
-### config FEATURE_FULL_LIBBUSYBOX
-###     bool "Feature-complete libbusybox"
-###     default n if !FEATURE_SHARED_BUSYBOX
-###     depends on BUILD_LIBBUSYBOX
-###     help
-###       Build a libbusybox with the complete feature-set, disregarding
-###       the actually selected config.
-###
-###       Normally, libbusybox will only contain the features which are
-###       used by busybox itself. If you plan to write a separate
-###       standalone application which uses libbusybox say 'Y'.
-###
-###       Note: libbusybox is GPL, not LGPL, and exports no stable API that
-###       might act as a copyright barrier. We can and will modify the
-###       exported function set between releases (even minor version number
-###       changes), and happily break out-of-tree features.
-###
-###       Say 'N' if in doubt.
+          This feature allows every applet to be built as a really tiny
+          separate executable linked against the library:
+
+          $ size 0_lib/l*
+            text  data   bss     dec    hex filename
+             939   212    28    1179    49b 0_lib/last
+             939   212    28    1179    49b 0_lib/less
+          919138  8328  1556  929022  e2cfe 0_lib/libbusybox.so.1.N.M
+
+          This is useful on NOMMU systems which are not capable
+          of sharing executables, but are capable of sharing code
+          in dynamic libraries.
+
+config FEATURE_LIBBUSYBOX_STATIC
+        bool "Pull in all external references into libbusybox"
+        default n
+        depends on BUILD_LIBBUSYBOX
+        help
+          Make libbusybox library independent, not using or requiring
+          any other shared libraries.
 
 config FEATURE_INDIVIDUAL
         bool "Produce a binary for each applet, linked against libbusybox"
diff --git a/scripts/trylink b/scripts/trylink
index 9f288c141..ba2d265bc 100755
--- a/scripts/trylink
+++ b/scripts/trylink
@@ -91,7 +91,9 @@ fi
 
 START_GROUP="-Wl,--start-group"
 END_GROUP="-Wl,--end-group"
-INFO_OPTS="-Wl,--warn-common -Wl,-Map,$EXE.map -Wl,--verbose"
+INFO_OPTS() {
+        echo "-Wl,--warn-common -Wl,-Map,$EXE.map -Wl,--verbose"
+}
 
 # gold may not support --sort-common (yet)
 SORT_COMMON="-Wl,--sort-common"
@@ -194,7 +196,7 @@ if ! test -f busybox_ldscript; then
             $GC_SECTIONS \
             $START_GROUP $O_FILES $A_FILES $END_GROUP \
             $l_list \
-            $INFO_OPTS \
+            `INFO_OPTS` \
     || {
         cat $EXE.out
         exit 1
@@ -225,7 +227,7 @@ else
             -Wl,-T,busybox_ldscript \
             $START_GROUP $O_FILES $A_FILES $END_GROUP \
             $l_list \
-            $INFO_OPTS \
+            `INFO_OPTS` \
     || {
         cat $EXE.out
         exit 1
@@ -244,10 +246,14 @@ if test "$CONFIG_BUILD_LIBBUSYBOX" = y; then
     }
     ln -s "libbusybox.so.$BB_VER" "$sharedlib_dir"/libbusybox.so 2>/dev/null
 
+    # Yes, "ld -shared -static" is a thing. It's a shared library which is itself static.
+    LBB_STATIC=""
+    test "$CONFIG_FEATURE_LIBBUSYBOX_STATIC" = y && LBB_STATIC="-Wl,-static"
+
     EXE="$sharedlib_dir/libbusybox.so.${BB_VER}_unstripped"
     try $CC $CFLAGS $LDFLAGS \
             -o $EXE \
-            -shared -fPIC \
+            -shared -fPIC $LBB_STATIC \
             -Wl,--enable-new-dtags \
             -Wl,-z,combreloc \
             -Wl,-soname="libbusybox.so.$BB_VER" \
@@ -256,7 +262,7 @@ if test "$CONFIG_BUILD_LIBBUSYBOX" = y; then
             $SORT_SECTION \
             $START_GROUP $A_FILES $END_GROUP \
             $l_list \
-            $INFO_OPTS \
+            `INFO_OPTS` \
     || {
         echo "Linking $EXE failed"
         cat $EXE.out
@@ -277,7 +283,7 @@ if test "$CONFIG_FEATURE_SHARED_BUSYBOX" = y; then
             $START_GROUP $O_FILES $END_GROUP \
             -L"$sharedlib_dir" -lbusybox \
             $l_list \
-            $INFO_OPTS \
+            `INFO_OPTS` \
     || {
         echo "Linking $EXE failed"
         cat $EXE.out