From c7ddafbe6dbcc805a9758c4313f2d6b902983343 Mon Sep 17 00:00:00 2001
From: Rickard Green <rickard@erlang.org>
Date: Fri, 21 Feb 2014 09:29:40 +0100
Subject: Always default to disabled floating point exceptions on Linux

This since there exist unresolved stability issues in the implementation
for Linux.
---
 HOWTO/INSTALL.md  |  7 ++++++-
 erts/configure.in |  5 +++++
 otp_build         | 18 ++++++++----------
 3 files changed, 19 insertions(+), 11 deletions(-)

diff --git a/HOWTO/INSTALL.md b/HOWTO/INSTALL.md
index 533960ef99..fd0108f1de 100644
--- a/HOWTO/INSTALL.md
+++ b/HOWTO/INSTALL.md
@@ -268,6 +268,11 @@ Some of the available `configure` options are:
     default if possible)
 *   `--{enable,disable}-hipe` - HiPE support (enabled by default on supported
     platforms)
+*   `--{enable,disable}-fp-exceptions` - Floating point exceptions (an
+    optimization for floating point operations). The default differs
+    depending on operating system and hardware platform. Note that by
+    enabling this you might get a seemingly working system that sometimes
+    fail on floating point operations.
 *   `--enable-darwin-universal` - Build universal binaries on darwin i386.
 *   `--enable-darwin-64bit` - Build 64-bit binaries on darwin
 *   `--enable-m64-build` - Build 64-bit binaries using the `-m64` flag to
@@ -288,7 +293,7 @@ Some of the available `configure` options are:
     memory accesses. If `configure` should inform you about no native atomic
     implementation available, you typically want to try using the
     `libatomic_ops` library. It can be downloaded from
-    <http://www.hpl.hp.com/research/linux/atomic_ops/>.
+    <https://github.com/ivmai/libatomic_ops/>.
 *   `--disable-smp-require-native-atomics` - By default `configure` will
     fail if an SMP runtime system is about to be built, and no implementation
     for native atomic memory accesses can be found. If this happens, you are
diff --git a/erts/configure.in b/erts/configure.in
index 8d245252b5..0933b124df 100644
--- a/erts/configure.in
+++ b/erts/configure.in
@@ -2767,6 +2767,11 @@ esac
 
 if test X${enable_fp_exceptions} = Xauto ; then
    case $host_os in
+   	*linux*)
+	      enable_fp_exceptions=no
+	      AC_MSG_NOTICE([Floating point exceptions disabled by default on Linux]) ;;
+	      *)
+	      ;;
 	darwin*)
 	      enable_fp_exceptions=no
 	      AC_MSG_NOTICE([Floating point exceptions disabled by default on MacOS X]) ;;
diff --git a/otp_build b/otp_build
index f5a7a0be44..5f41e40f5f 100755
--- a/otp_build
+++ b/otp_build
@@ -173,6 +173,14 @@ determine_version_controller ()
 # Special static config flags for certain platforms are set here  
 set_config_flags ()
 {
+	#
+	# NOTE! Do not add special flags here without a *very good*
+	#       reason. We normally do not want "./otp_build configure"
+	#       and "./configure" to produce different results.
+	#       However, in the Windows case this does not matter, since
+	#       the only supported way to build on Windows is using
+	#       otp_build.
+	#
 	# * Extra flags to pass to configure are placed in `CONFIG_FLAGS'.
 	# * The command line is no longer added to `CONFIG_FLAGS' by
 	#   `set_config_flags'. It is instead passed directly to
@@ -183,16 +191,6 @@ set_config_flags ()
 	#   (in the cross compilation case the whole command line as well as
 	#   the cross configuration have been moved here). 
 
-	if target_contains linux; then 
-	        XX=`echo $* | grep -v able-fp-exceptions`
-		if [ "$*" = "$XX" ]; then 
-		    CONFIG_FLAGS="$CONFIG_FLAGS --disable-fp-exceptions"
-		fi
-	fi
-	if target_contains "univel-sysv4"; then
-		CONFIG_FLAGS="$CONFIG_FLAGS --x-libraries=/usr/lib/X11"
-	fi
-
 	if target_contains free_source; then
 		CONFIG_FLAGS="$CONFIG_FLAGS --host=$TARGET"
 	fi
-- 
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