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-rw-r--r--INSTALL.md3
-rw-r--r--erts/aclocal.m459
2 files changed, 51 insertions, 11 deletions
diff --git a/INSTALL.md b/INSTALL.md
index 2567b791e5..1061c5187a 100644
--- a/INSTALL.md
+++ b/INSTALL.md
@@ -277,7 +277,8 @@ Some of the available `configure` options are:
x86 processors before pentium 4 (back to 486) in the ethread library. If
not passed the ethread library (part of the runtime system) will use
instructions that first appeared on the pentium 4 processor when building
- for x86.
+ for x86. This option will be automatically enabled if required on the
+ build machine.
* `--with-libatomic_ops=PATH` - Use the `libatomic_ops` library for atomic
memory accesses. If `configure` should inform you about no native atomic
implementation available, you typically want to try using the
diff --git a/erts/aclocal.m4 b/erts/aclocal.m4
index 82014fe23d..3a951860e5 100644
--- a/erts/aclocal.m4
+++ b/erts/aclocal.m4
@@ -994,8 +994,8 @@ case "$THR_LIB_NAME" in
case "$host_cpu" in
sun4u | sparc64 | sun4v)
- ethr_have_native_atomics=yes;;
- i86pc | i386 | i486 | i586 | i686 | x86_64 | amd64)
+ ethr_have_native_atomics=yes;;
+ i86pc | i*86 | x86_64 | amd64)
ethr_have_native_atomics=yes;;
macppc | ppc | "Power Macintosh")
ethr_have_native_atomics=yes;;
@@ -1099,21 +1099,60 @@ AC_ARG_ENABLE(prefer-gcc-native-ethr-impls,
test $enable_prefer_gcc_native_ethr_impls = yes &&
AC_DEFINE(ETHR_PREFER_GCC_NATIVE_IMPLS, 1, [Define if you prefer gcc native ethread implementations])
+AC_ARG_WITH(libatomic_ops,
+ AS_HELP_STRING([--with-libatomic_ops=PATH],
+ [use libatomic_ops with the ethread library]))
+
AC_ARG_ENABLE(ethread-pre-pentium4-compatibility,
AS_HELP_STRING([--enable-ethread-pre-pentium4-compatibility],
[enable compatibility with x86 processors before pentium 4 (back to 486) in the ethread library]),
-[ case "$enableval" in
- yes) enable_ethread_pre_pentium4_compatibility=yes ;;
- *) enable_ethread_pre_pentium4_compatibility=no ;;
- esac ], enable_ethread_pre_pentium4_compatibility=no)
+[
+ case "$enable_ethread_pre_pentium4_compatibility" in
+ yes|no) ;;
+ *) enable_ethread_pre_pentium4_compatibility=check;;
+ esac
+],
+[enable_ethread_pre_pentium4_compatibility=check])
+
+test "$cross_compiling" != "yes" || enable_ethread_pre_pentium4_compatibility=no
+
+case "$enable_ethread_pre_pentium4_compatibility-$host_cpu" in
+ check-i86pc | check-i*86)
+ AC_MSG_CHECKING([whether pre pentium 4 compatibility should forced])
+ AC_RUN_IFELSE([
+#if defined(__GNUC__)
+# if defined(ETHR_PREFER_LIBATOMIC_OPS_NATIVE_IMPLS)
+# define CHECK_LIBATOMIC_OPS__
+# else
+# define CHECK_GCC_ASM__
+# endif
+#elif defined(ETHR_HAVE_LIBATOMIC_OPS)
+# define CHECK_LIBATOMIC_OPS__
+#endif
+#if defined(CHECK_LIBATOMIC_OPS__)
+#include "atomic_ops.h"
+#endif
+int main(void)
+{
+#if defined(CHECK_GCC_ASM__)
+ __asm__ __volatile__("mfence" : : : "memory");
+#elif defined(CHECK_LIBATOMIC_OPS__)
+ AO_nop_full();
+#endif
+ return 0;
+}
+ ],
+ [enable_ethread_pre_pentium4_compatibility=no],
+ [enable_ethread_pre_pentium4_compatibility=yes],
+ [enable_ethread_pre_pentium4_compatibility=no])
+ AC_MSG_RESULT([$enable_ethread_pre_pentium4_compatibility]);;
+ *)
+ ;;
+esac
test $enable_ethread_pre_pentium4_compatibility = yes &&
AC_DEFINE(ETHR_PRE_PENTIUM4_COMPAT, 1, [Define if you want compatibilty with x86 processors before pentium4.])
-AC_ARG_WITH(libatomic_ops,
- AS_HELP_STRING([--with-libatomic_ops=PATH],
- [use libatomic_ops with the ethread library]))
-
AC_DEFINE(ETHR_HAVE_ETHREAD_DEFINES, 1, \
[Define if you have all ethread defines])