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Greg Jandl to SDL I did some digging, and I think I've found a better solution. By including some additional .m4 macros in the acinclude directory (http://www.gnu.org/software/autoconf-archive/ax_check_compiler_flags.html, http://www.gnu.org/software/autoconf-archive/ax_gcc_archflag.html and http://www.gnu.org/software/autoconf-archive/ax_gcc_x86_cpuid.html) then using the patch below (same as previous patch + one line change to configure.in), SDL will build correctly out of the box. The arch can then be overridden by --with-gcc-arch=<arch> (most will probably want to build with i686 there for general distribution) or --without-gcc-arch, to disable setting the arch all together. On my Atom netbook, I get -march=PentiumPro by default, which works great, as does --with-gcc-arch=i686.
author Sam Lantinga <slouken@libsdl.org>
date Tue, 18 Jan 2011 22:40:45 -0800
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1 # ===========================================================================
2 # http://www.gnu.org/software/autoconf-archive/ax_gcc_x86_cpuid.html
3 # ===========================================================================
4 #
5 # SYNOPSIS
6 #
7 # AX_GCC_X86_CPUID(OP)
8 #
9 # DESCRIPTION
10 #
11 # On Pentium and later x86 processors, with gcc or a compiler that has a
12 # compatible syntax for inline assembly instructions, run a small program
13 # that executes the cpuid instruction with input OP. This can be used to
14 # detect the CPU type.
15 #
16 # On output, the values of the eax, ebx, ecx, and edx registers are stored
17 # as hexadecimal strings as "eax:ebx:ecx:edx" in the cache variable
18 # ax_cv_gcc_x86_cpuid_OP.
19 #
20 # If the cpuid instruction fails (because you are running a
21 # cross-compiler, or because you are not using gcc, or because you are on
22 # a processor that doesn't have this instruction), ax_cv_gcc_x86_cpuid_OP
23 # is set to the string "unknown".
24 #
25 # This macro mainly exists to be used in AX_GCC_ARCHFLAG.
26 #
27 # LICENSE
28 #
29 # Copyright (c) 2008 Steven G. Johnson <stevenj@alum.mit.edu>
30 # Copyright (c) 2008 Matteo Frigo
31 #
32 # This program is free software: you can redistribute it and/or modify it
33 # under the terms of the GNU General Public License as published by the
34 # Free Software Foundation, either version 3 of the License, or (at your
35 # option) any later version.
36 #
37 # This program is distributed in the hope that it will be useful, but
38 # WITHOUT ANY WARRANTY; without even the implied warranty of
39 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
40 # Public License for more details.
41 #
42 # You should have received a copy of the GNU General Public License along
43 # with this program. If not, see <http://www.gnu.org/licenses/>.
44 #
45 # As a special exception, the respective Autoconf Macro's copyright owner
46 # gives unlimited permission to copy, distribute and modify the configure
47 # scripts that are the output of Autoconf when processing the Macro. You
48 # need not follow the terms of the GNU General Public License when using
49 # or distributing such scripts, even though portions of the text of the
50 # Macro appear in them. The GNU General Public License (GPL) does govern
51 # all other use of the material that constitutes the Autoconf Macro.
52 #
53 # This special exception to the GPL applies to versions of the Autoconf
54 # Macro released by the Autoconf Archive. When you make and distribute a
55 # modified version of the Autoconf Macro, you may extend this special
56 # exception to the GPL to apply to your modified version as well.
57
58 #serial 7
59
60 AC_DEFUN([AX_GCC_X86_CPUID],
61 [AC_REQUIRE([AC_PROG_CC])
62 AC_LANG_PUSH([C])
63 AC_CACHE_CHECK(for x86 cpuid $1 output, ax_cv_gcc_x86_cpuid_$1,
64 [AC_RUN_IFELSE([AC_LANG_PROGRAM([#include <stdio.h>], [
65 int op = $1, eax, ebx, ecx, edx;
66 FILE *f;
67 __asm__("cpuid"
68 : "=a" (eax), "=b" (ebx), "=c" (ecx), "=d" (edx)
69 : "a" (op));
70 f = fopen("conftest_cpuid", "w"); if (!f) return 1;
71 fprintf(f, "%x:%x:%x:%x\n", eax, ebx, ecx, edx);
72 fclose(f);
73 return 0;
74 ])],
75 [ax_cv_gcc_x86_cpuid_$1=`cat conftest_cpuid`; rm -f conftest_cpuid],
76 [ax_cv_gcc_x86_cpuid_$1=unknown; rm -f conftest_cpuid],
77 [ax_cv_gcc_x86_cpuid_$1=unknown])])
78 AC_LANG_POP([C])
79 ])