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-rw-r--r--erts/configure.in25
1 files changed, 23 insertions, 2 deletions
diff --git a/erts/configure.in b/erts/configure.in
index f248cbe34d..481dfe405e 100644
--- a/erts/configure.in
+++ b/erts/configure.in
@@ -2,7 +2,7 @@ dnl Process this file with autoconf to produce a configure script. -*-m4-*-
dnl %CopyrightBegin%
dnl
-dnl Copyright Ericsson AB 1997-2014. All Rights Reserved.
+dnl Copyright Ericsson AB 1997-2015. All Rights Reserved.
dnl
dnl The contents of this file are subject to the Erlang Public License,
dnl Version 1.1, (the "License"); you may not use this file except in
@@ -1105,10 +1105,31 @@ if test $ERTS_BUILD_SMP_EMU = yes; then
case "$ethr_have_native_atomics-$smp_require_native_atomics-$ethr_have_native_spinlock" in
yes-*)
+ if test "$ethr_native_atomic_implementation" = "gcc_sync"; then
+ test -f "$ERL_TOP/erts/CONF_INFO" ||
+ echo "" > "$ERL_TOP/erts/CONF_INFO"
+ cat >> $ERL_TOP/erts/CONF_INFO <<EOF
+
+ WARNING:
+ Only gcc's __sync_* builtins available for
+ atomic memory access. This will cause lots
+ of expensive and unnecessary memory barrier
+ instructions to be issued which will make
+ the performance of the runtime system
+ suffer. You are *strongly* advised to
+ upgrade to a gcc version that supports the
+ __atomic_* builtins (at least gcc version
+ 4.7) or build with libatomic_ops. See the
+ "Atomic Memory Operations and the VM"
+ chapter of \$ERL_TOP/HOWTO/INSTALL.md for
+ more information.
+
+EOF
+ fi
;;
no-yes-*)
- AC_MSG_ERROR([No native atomic implementation found. See Configuring section in INSTALL.md for more information.])
+ AC_MSG_ERROR([No native atomic implementation found. See the \"Atomic Memory Operations and the VM\" chapter of \$ERL_TOP/HOWTO/INSTALL.md for more information.])
;;
no-no-yes)