From 1f9ed02caffb269e5fc6fbdf19fc9ba05a79e628 Mon Sep 17 00:00:00 2001
From: Denys Vlasenko <vda.linux@googlemail.com>
Date: Tue, 23 Feb 2021 23:09:49 +0100
Subject: [PATCH] trylink: do not drop libs from CONFIG_EXTRA_LDLIBS

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
---
 Makefile        |  1 +
 Makefile.flags  |  5 -----
 scripts/trylink | 17 ++++++++++++-----
 3 files changed, 13 insertions(+), 10 deletions(-)

diff --git a/Makefile b/Makefile
index 17f55dce2..ea182325d 100644
--- a/Makefile
+++ b/Makefile
@@ -612,6 +612,7 @@ quiet_cmd_busybox__ ?= LINK    $@
       "$(core-y)" \
       "$(libs-y)" \
       "$(LDLIBS)" \
+      "$(CONFIG_EXTRA_LDLIBS)" \
       && $(srctree)/scripts/generate_BUFSIZ.sh --post include/common_bufsiz.h
 
 # Generate System.map
diff --git a/Makefile.flags b/Makefile.flags
index 7a445c3b5..3b02bfaac 100644
--- a/Makefile.flags
+++ b/Makefile.flags
@@ -209,11 +209,6 @@ LDFLAGS += $(strip $(subst ",,$(CONFIG_EXTRA_LDFLAGS)))
 #"))
 endif
 
-ifneq ($(CONFIG_EXTRA_LDLIBS),)
-LDLIBS += $(strip $(subst ",,$(CONFIG_EXTRA_LDLIBS)))
-#"))
-endif
-
 # Busybox is a stack-fatty so make sure we increase default size
 # TODO: use "make stksizes" to find & fix big stack users
 # (we stole scripts/checkstack.pl from the kernel... thanks guys!)
diff --git a/scripts/trylink b/scripts/trylink
index 6b74f092d..2255deee7 100755
--- a/scripts/trylink
+++ b/scripts/trylink
@@ -1,5 +1,6 @@
 #!/bin/sh
 
+#debug=true
 debug=false
 
 # Linker flags used:
@@ -77,7 +78,13 @@ CFLAGS="$3"
 LDFLAGS="$4"
 O_FILES="$5"
 A_FILES="$6"
+# We try to drop libraries from LDLIBS if build works without them,
+# but ones from CONFIG_EXTRA_LDLIBS are always linked in.
+# (For example, musl has stub utmp implementation, and if you link with
+# a real utmp library in LDLIBS, dropping it "works" but resulting binary
+# does not work properly).
 LDLIBS="$7"
+CONFIG_EXTRA_LDLIBS="$8"
 
 # The --sort-section option is not supported by older versions of ld
 SORT_SECTION="-Wl,--sort-section,alignment"
@@ -125,8 +132,8 @@ LDLIBS=`echo "$LDLIBS" | xargs -n1 | sort | uniq | xargs`
 # First link with all libs. If it fails, bail out
 echo "Trying libraries: $LDLIBS"
 # "lib1 lib2 lib3" -> "-llib1 -llib2 -llib3"
-l_list=`echo " $LDLIBS " | sed -e 's: \([^- ][^ ]*\): -l\1:g'`
-test "x$l_list" != "x" && l_list="$START_GROUP $l_list $END_GROUP"
+l_list=`echo " $LDLIBS $CONFIG_EXTRA_LDLIBS " | sed -e 's: \([^- ][^ ]*\): -l\1:g' -e 's/^ *//'`
+test x"$l_list" != x"" && l_list="$START_GROUP $l_list $END_GROUP"
 try $CC $CFLAGS $LDFLAGS \
 	-o $EXE \
 	$SORT_COMMON \
@@ -151,7 +158,7 @@ while test "$LDLIBS"; do
     for one in $LDLIBS; do
 	without_one=`echo " $LDLIBS " | sed "s/ $one / /g" | xargs`
 	# "lib1 lib2 lib3" -> "-llib1 -llib2 -llib3"
-	l_list=`echo " $without_one " | sed -e 's: \([^- ][^ ]*\): -l\1:g'`
+	l_list=`echo " $without_one $CONFIG_EXTRA_LDLIBS " | sed -e 's: \([^- ][^ ]*\): -l\1:g' -e 's/^ *//'`
 	test x"$l_list" != x"" && l_list="$START_GROUP $l_list $END_GROUP"
 	$debug && echo "Trying -l options: '$l_list'"
 	try $CC $CFLAGS $LDFLAGS \
@@ -179,8 +186,8 @@ done
 
 # Make the binary with final, minimal list of libs
 echo "Final link with: ${LDLIBS:-<none>}"
-l_list=`echo " $LDLIBS " | sed -e 's: \([^- ][^ ]*\): -l\1:g'`
-test "x$l_list" != "x" && l_list="$START_GROUP $l_list $END_GROUP"
+l_list=`echo " $LDLIBS $CONFIG_EXTRA_LDLIBS " | sed -e 's: \([^- ][^ ]*\): -l\1:g' -e 's/^ *//'`
+test x"$l_list" != x"" && l_list="$START_GROUP $l_list $END_GROUP"
 # --verbose gives us gobs of info to stdout (e.g. linker script used)
 if ! test -f busybox_ldscript; then
     try $CC $CFLAGS $LDFLAGS \