diff -rup binutils.orig/ld/emultempl/elf32.em binutils-2.29.1/ld/emultempl/elf32.em

--- binutils.orig/ld/emultempl/elf32.em	2018-01-16 11:34:58.040749108 +0000

+++ binutils-2.29.1/ld/emultempl/elf32.em	2018-01-16 11:35:35.697303875 +0000

@@ -2666,6 +2666,8 @@ fragment <

     case 'z':

       if (strcmp (optarg, "defs") == 0)

 	link_info.unresolved_syms_in_objects = RM_GENERATE_ERROR;

+      else if (strcmp (optarg, "undefs") == 0)

+	link_info.unresolved_syms_in_objects = RM_IGNORE;

       else if (strcmp (optarg, "muldefs") == 0)

 	link_info.allow_multiple_definition = TRUE;

       else if (CONST_STRNEQ (optarg, "max-page-size="))

Only in binutils-2.29.1/ld/emultempl: elf32.em.orig

diff -rup binutils.orig/ld/ld.texinfo binutils-2.29.1/ld/ld.texinfo

--- binutils.orig/ld/ld.texinfo	2018-01-16 11:34:58.208747127 +0000

+++ binutils-2.29.1/ld/ld.texinfo	2018-01-16 11:35:35.699303851 +0000

@@ -1125,8 +1125,9 @@ Generate common symbols with the STT_COM

 link.

 @item defs

-Disallows undefined symbols in object files.  Undefined symbols in

-shared libraries are still allowed.

+Report unresolved symbol references from regular object files.  This

+is done even if the linker is creating a non-symbolic shared library.

+This option is the inverse of @samp{-z undefs}.

 @item execstack

 Marks the object as requiring executable stack.

@@ -1279,6 +1280,11 @@ Generate GNU_PROPERTY_X86_FEATURE_1_SHST

 to indicate compatibility with Intel Shadow Stack.  Supported for

 Linux/i386 and Linux/x86_64.

+@item undefs

+Do not report unresolved symbol references from regular object files,

+either when creating an executable, or when creating a shared library.

+This option is the inverse of @samp{-z defs}.

+

 @end table

 Other keywords are ignored for Solaris compatibility.

@@ -1684,6 +1690,7 @@ while linking a large executable.

 @kindex --no-undefined

 @kindex -z defs

+@kindex -z undefs

 @item --no-undefined

 @itemx -z defs

 Report unresolved symbol references from regular object files.  This

@@ -1692,6 +1699,8 @@ The switch @option{--[no-]allow-shlib-un

 behaviour for reporting unresolved references found in shared

 libraries being linked in.

+The effects of this option can be reverted by using @code{-z undefs}.

+

 @kindex --allow-multiple-definition

 @kindex -z muldefs

 @item --allow-multiple-definition

Only in binutils-2.29.1/ld: ld.texinfo.orig

diff -rup binutils.orig/ld/NEWS binutils-2.29.1/ld/NEWS

--- binutils.orig/ld/NEWS	2018-01-16 11:34:58.209747115 +0000

+++ binutils-2.29.1/ld/NEWS	2018-01-16 11:35:57.855041557 +0000

@@ -1,5 +1,7 @@

 -*- text -*-

+* Add "-z undefs" command line option as the inverse of the "-z defs" option.

+

 Changes in 2.29:

 * Support for -z shstk in the x86 ELF linker to generate

Only in binutils-2.29.1/ld: NEWS.orig

Only in binutils-2.29.1/ld: NEWS.rej