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RFC: -z defs: documentation and reverting
- From: Nick Clifton <nickc at redhat dot com>
- To: binutils at sourceware dot org
- Date: Wed, 10 Jan 2018 10:57:23 +0000
- Subject: RFC: -z defs: documentation and reverting
- Authentication-results: sourceware.org; auth=none
Hi Guys,
Currently we have no obvious way to revert the action of the "-z defs"
command line option. The "--unresolved-symbols=ignore-in-object-files"
does pretty much what is needed, but it is non-obvious and it also
touches the setting for reporting unresolved symbol references from
shared libraries. So I am proposing adding a "-z undefs" option to be
the inverse of "-z defs". (I thought that "-z nodefs" might be
confusing since it implies banning all definitions, rather than
allowing them).
In addition the description of the "-z defs" option in the linker
documentation is misleading in one place, where it says:
'defs'
Disallows undefined symbols in object files. Undefined
symbols in shared libraries are still allowed.
whereas later on it gets it right:
'-z defs'
Report unresolved symbol references from regular object files.
This is done even if the linker is creating a non-symbolic shared
library. The switch '--[no-]allow-shlib-undefined' controls the
behaviour for reporting unresolved references found in shared
libraries being linked in.
So I am proposing apply the patch below. Any comments ?
Cheers
Nick
2018-01-10 Nick Clifton <nickc@redhat.com>
* emultempl/elf32.em (_handle_option): Add support for "-z undefs"
as the opposite of "-z defs".
* ld.texinfo: Document the new option. Update the description of
the -z defs option to make it clear that it does generate an error
if an undefined symbol reference is found in an object file whilst
creating a shared library.
* NEWS: Document this new feature.
diff --git a/ld/emultempl/elf32.em b/ld/emultempl/elf32.em
index a12aefa9cb..075d99d548 100644
--- a/ld/emultempl/elf32.em
+++ b/ld/emultempl/elf32.em
@@ -2648,6 +2648,8 @@ fragment <<EOF
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="))
diff --git a/ld/ld.texinfo b/ld/ld.texinfo
index 4fd12bb213..e9ec5a7fab 100644
--- a/ld/ld.texinfo
+++ b/ld/ld.texinfo
@@ -1147,8 +1147,9 @@ layout will be optimized to minimize memory pages if the system is
using pages of this size.
@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 dynamic-undefined-weak
@itemx nodynamic-undefined-weak
@@ -1281,6 +1282,11 @@ Report an error if DT_TEXTREL is set, i.e., if the binary has dynamic
relocations in read-only sections. Don't report an error if
@samp{notext} or @samp{textoff}.
+@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.
@@ -1686,6 +1692,7 @@ 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
@@ -1694,6 +1701,8 @@ The switch @option{--[no-]allow-shlib-undefined} controls the
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
diff --git a/ld/NEWS b/ld/NEWS
index 8326088b25..1cd775ae1c 100644
--- a/ld/NEWS
+++ b/ld/NEWS
@@ -1,4 +1,6 @@
-*- text -*-
+* Add "-z undefs" command line option as the inverse of the "-z defs" option.
+
* Add -z globalaudit command line option to force audit libraries to be run
for every dynamic object loaded by an executable - provided that the loader
supports this functionality.