-# mmap-anon.m4 serial 5
-dnl Copyright (C) 2005, 2007, 2009 Free Software Foundation, Inc.
+# mmap-anon.m4 serial 8
+dnl Copyright (C) 2005, 2007, 2009-2010 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
dnl with or without modifications, as long as this notice is preserved.
+# Detect how mmap can be used to create anonymous (not file-backed) memory
+# mappings.
+# - On Linux, AIX, OSF/1, Solaris, Cygwin, Interix, Haiku, both MAP_ANONYMOUS
+# and MAP_ANON exist and have the same value.
+# - On HP-UX, only MAP_ANONYMOUS exists.
+# - On MacOS X, FreeBSD, NetBSD, OpenBSD, only MAP_ANON exists.
+# - On IRIX, neither exists, and a file descriptor opened to /dev/zero must be
+# used.
+
AC_DEFUN([gl_FUNC_MMAP_ANON],
[
dnl Work around a bug of AC_EGREP_CPP in autoconf-2.57.
AC_REQUIRE([AC_PROG_EGREP])
dnl Persuade glibc <sys/mman.h> to define MAP_ANONYMOUS.
- AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
+ AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
- # Check for mmap()
- AC_FUNC_MMAP
+ # Check for mmap(). Don't use AC_FUNC_MMAP, because it checks too much: it
+ # fails on HP-UX 11, because MAP_FIXED mappings do not work. But this is
+ # irrelevant for anonymous mappings.
+ AC_CHECK_FUNC([mmap], [gl_have_mmap=yes], [gl_have_mmap=no])
# Try to allow MAP_ANONYMOUS.
gl_have_mmap_anonymous=no
- if test $ac_cv_func_mmap_fixed_mapped = yes; then
+ if test $gl_have_mmap = yes; then
AC_MSG_CHECKING([for MAP_ANONYMOUS])
AC_EGREP_CPP([I cant identify this map.], [
#include <sys/mman.h>