+
+# OVS_LINK2_IFELSE(SOURCE1, SOURCE2, [ACTION-IF-TRUE], [ACTION-IF-FALSE])
+# -------------------------------------------------------------
+# Based on AC_LINK_IFELSE, but tries to link both SOURCE1 and SOURCE2
+# into a program.
+#
+# This macro is borrowed from acinclude.m4 in GNU PSPP, which has the
+# following license:
+#
+# Copyright (C) 2005, 2006, 2007, 2009 Free Software Foundation, Inc.
+# This file is free software; the Free Software Foundation
+# gives unlimited permission to copy and/or distribute it,
+# with or without modifications, as long as this notice is preserved.
+#
+m4_define([OVS_LINK2_IFELSE],
+[m4_ifvaln([$1], [AC_LANG_CONFTEST([$1])])dnl
+mv conftest.$ac_ext conftest1.$ac_ext
+m4_ifvaln([$2], [AC_LANG_CONFTEST([$2])])dnl
+mv conftest.$ac_ext conftest2.$ac_ext
+rm -f conftest1.$ac_objext conftest2.$ac_objext conftest$ac_exeext
+ovs_link2='$CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS conftest1.$ac_ext conftest2.$ac_ext $LIBS >&5'
+AS_IF([_AC_DO_STDERR($ovs_link2) && {
+ test -z "$ac_[]_AC_LANG_ABBREV[]_werror_flag" ||
+ test ! -s conftest.err
+ } && test -s conftest$ac_exeext && {
+ test "$cross_compiling" = yes ||
+ AS_TEST_X([conftest$ac_exeext])
+ }],
+ [$3],
+ [echo "$as_me: failed source file 1 of 2 was:" >&5
+sed 's/^/| /' conftest1.$ac_ext >&5
+echo "$as_me: failed source file 2 of 2 was:" >&5
+sed 's/^/| /' conftest2.$ac_ext >&5
+ $4])
+dnl Delete also the IPA/IPO (Inter Procedural Analysis/Optimization)
+dnl information created by the PGI compiler (conftest_ipa8_conftest.oo),
+dnl as it would interfere with the next link command.
+rm -rf conftest.dSYM conftest1.dSYM conftest2.dSYM
+rm -f core conftest.err conftest1.err conftest2.err
+rm -f conftest1.$ac_objext conftest2.$ac_objext conftest*_ipa8_conftest*.oo
+rm -f conftest$ac_exeext
+rm -f m4_ifval([$1], [conftest1.$ac_ext]) m4_ifval([$2], [conftest1.$ac_ext])[]dnl
+])# OVS_LINK2_IFELSE
+
+dnl Defines USE_LINKER_SECTIONS to 1 if the compiler supports putting
+dnl variables in sections with user-defined names and the linker
+dnl automatically defines __start_SECNAME and __stop_SECNAME symbols
+dnl that designate the start and end of the sections.
+AC_DEFUN([OVS_CHECK_LINKER_SECTIONS],
+ [AC_CACHE_CHECK(
+ [for user-defined linker section support],
+ [ovs_cv_use_linker_sections],
+ [OVS_LINK2_IFELSE(
+ [AC_LANG_SOURCE(
+ [int a __attribute__((__section__("mysection"))) = 1;
+ int b __attribute__((__section__("mysection"))) = 2;
+ int c __attribute__((__section__("mysection"))) = 3;])],
+ [AC_LANG_PROGRAM(
+ [#include <stdio.h>
+ extern int __start_mysection;
+ extern int __stop_mysection;],
+ [int n_ints = &__stop_mysection - &__start_mysection;
+ int *i;
+ for (i = &__start_mysection; i < &__start_mysection + n_ints; i++) {
+ printf("%d\n", *i);
+ }])],
+ [ovs_cv_use_linker_sections=yes],
+ [ovs_cv_use_linker_sections=no])])
+ if test $ovs_cv_use_linker_sections = yes; then
+ AC_DEFINE([USE_LINKER_SECTIONS], [1],
+ [Define to 1 if the compiler support putting variables
+ into sections with user-defined names and the linker
+ automatically defines __start_SECNAME and __stop_SECNAME
+ symbols that designate the start and end of the section.])
+ fi])