Gentoo Archives: gentoo-user

From: Beau Henderson <beau@××××××××××××.com>
To: gentoo-user@l.g.o
Subject: Re: [gentoo-user] -march=native
Date: Wed, 30 Jun 2010 22:21:36
Message-Id: 4C2BC34E.7050107@thehenderson.com
In Reply to: Re: [gentoo-user] -march=native by Paul Hartman
1 On 07/01/10 00:30, Paul Hartman wrote:
2 > On Tue, Jun 29, 2010 at 8:09 PM, Beau Henderson<beau@××××××××××××.com> wrote:
3 >> On 06/30/10 08:07, Paul Hartman wrote:
4 >>>
5 >>> 2010/6/29 Hasan SAHIN<hasan.sahin@×××.com>:
6 >>>>
7 >>>> Hello all,
8 >>>>
9 >>>> I am using Athlon64 X2 processor with the
10 >>>> CFLAGS="-march=k8 -O2 -pipe -fomit-frame-pointer" option.
11 >>>>
12 >>>> Can I use the -march=native option instead of that?
13 >>>
14 >>> You can see which options -march=native would use by running this command:
15 >>>
16 >>> gcc -Q --help=target -march=native
17 >>>
18 >>> (thanks to Daniel Iliev for the tip)
19 >>>
20 >>
21 >> Perhaps I'm missing something but running the above gives me the impression
22 >> that -march=native actually only configures the bare minimal install. I'm
23 >> not seeing -mmmx or -msse3 enabled on my k8-sse3 for instance ( amongst much
24 >> else ).
25 >
26 > What -march setting is it showing in that output? The MMX (etc) may be
27 > enabled implicitly instead of explicitly.
28 >
29 > It's also possible that the CPU detection is failing to identify your
30 > CPU. In that case you could probably file a bug report about it.
31 >
32
33 The correct -march is being displayed, I just can't make sense of the options showing as [disabled].
34 While the option may be implied by the -march settings, it just makes sense to me that the option
35 should show as enabled. Indeed, with my core2 machine the majority of the options do display as
36 enable as expected, just not with my k8-see3 @native.
37
38 I wonder if perhaps it might be possible to compile an application that uses all these functions and
39 then assess ( somehow ) the binaries afterwards to see if they were compiled in and working correctly ?
40
41 Here's what I'm seeing on my k8-sse3: http://pastebin.com/PfMiTnx5
42
43 And my core2: http://pastebin.com/7WerGwkX

Replies

Subject Author
Re: [gentoo-user] -march=native James Cloos <cloos@×××××××.com>