diff -Naur gcc-6-20160609/libbacktrace/configure gcc-6-patched/libbacktrace/configure
--- gcc-6-20160609/libbacktrace/configure	2015-12-18 05:36:11.000000000 +0100
+++ gcc-6-patched/libbacktrace/configure	2017-02-28 12:28:13.588471194 +0100
@@ -11719,6 +11719,7 @@
 
 
 
+
 # Test for __sync support.
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking __sync extensions" >&5
 $as_echo_n "checking __sync extensions... " >&6; }
@@ -11730,6 +11731,10 @@
    hppa*-*-hpux*) libbacktrace_cv_sys_sync=no ;;
    *) libbacktrace_cv_sys_sync=yes ;;
    esac
+   case "${target}" in
+   sparc-*-rtems*) libbacktrace_cv_sys_sync=no ;;
+   *) libbacktrace_cv_sys_sync=yes ;;
+   esac
  else
    cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
diff -Naur gcc-6-20160609/libbacktrace/configure.ac gcc-6-patched/libbacktrace/configure.ac
--- gcc-6-20160609/libbacktrace/configure.ac	2016-01-04 15:30:50.000000000 +0100
+++ gcc-6-patched/libbacktrace/configure.ac	2017-02-28 12:28:07.732560384 +0100
@@ -168,6 +168,7 @@
 [PIC_FLAG=-fPIC], [PIC_FLAG=])
 AC_SUBST(PIC_FLAG)
 
+
 # Test for __sync support.
 AC_CACHE_CHECK([__sync extensions],
 [libbacktrace_cv_sys_sync],
@@ -176,6 +177,10 @@
    hppa*-*-hpux*) libbacktrace_cv_sys_sync=no ;;
    *) libbacktrace_cv_sys_sync=yes ;;
    esac
+   case "${target}" in
+   sparc-*-rtems*) libbacktrace_cv_sys_sync=no ;;
+   *) libbacktrace_cv_sys_sync=yes ;;
+   esac
  else
    AC_LINK_IFELSE(
      [AC_LANG_PROGRAM([int i;],