[gentoo-amd64] Correct -march in make.conf

[gentoo-amd64] Correct -march in make.conf

[Mark Haney]

I've been using -mcpu since I started using gentoo, but have been
noticing the '-mcpu is deprecated etc.' messages when updating.  Being
the paranoid I am, I'd like to get rid of those, but haven't found the
correct option to use for -march.  Is it the same as -mcpu?  Or what's
the correct one for amd64?


-- 
Ita erat quando hic adveni.

Mark Haney
Sr. Systems Administrator
ERC Broadband
(828) 350-2415
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RE: [gentoo-amd64] Correct -march in make.conf

[David Pyke]

-march=k8 is the standard but -march=k8, opteron, athlon64 or, athlon-fx are
all synonyms

http://gcc.gnu.org/onlinedocs/gcc-4.1.1/gcc/i386-and-x86_002d64-Options.html
#i386-and-x86_002d64-Options

-----Original Message-----
From: Mark Haney [mailto:mhaney@ercbroadband.org] 
Sent: Monday, December 18, 2006 1:07 PM
To: gentoo-amd64@lists.gentoo.org
Subject: [gentoo-amd64] Correct -march in make.conf

I've been using -mcpu since I started using gentoo, but have been noticing
the '-mcpu is deprecated etc.' messages when updating.  Being the paranoid I
am, I'd like to get rid of those, but haven't found the correct option to
use for -march.  Is it the same as -mcpu?  Or what's the correct one for
amd64?


--
Ita erat quando hic adveni.

Mark Haney
Sr. Systems Administrator
ERC Broadband
(828) 350-2415
--
gentoo-amd64@gentoo.org mailing list

-- 
gentoo-amd64@gentoo.org mailing list

Re: [gentoo-amd64] Correct -march in make.conf

[Boyd Stephen Smith Jr.]

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On Monday 18 December 2006 12:06, "Mark Haney" <mhaney@ercbroadband.org> 
wrote about '[gentoo-amd64] Correct -march in make.conf':
> I've been using -mcpu since I started using gentoo, but have been
> noticing the '-mcpu is deprecated etc.' messages when updating.  Being
> the paranoid I am, I'd like to get rid of those, but haven't found the
> correct option to use for -march.  Is it the same as -mcpu?  Or what's
> the correct one for amd64?

I'm using -march=opteron however, that may not be appropriate for 
non-opteron amd64 chips.  The gcc info pages list the available options, 
along with a short description of what CPUs they target.  The contents 
of /proc/cpuinfo are relevant if you'd like us to further advise you.

-- 
"If there's one thing we've established over the years,
it's that the vast majority of our users don't have the slightest
clue what's best for them in terms of package stability."
-- Gentoo Developer Ciaran McCreesh

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Re: [gentoo-amd64] Correct -march in make.conf

[Etaoin Shrdlu]

On Monday 18 December 2006 19:06, Mark Haney wrote:

> I've been using -mcpu since I started using gentoo, but have been
> noticing the '-mcpu is deprecated etc.' messages when updating.  Being
> the paranoid I am, I'd like to get rid of those, but haven't found the
> correct option to use for -march.  Is it the same as -mcpu?  Or what's
> the correct one for amd64?

You can use -mtune in place of -mcpu. If you don't need binary 
compatibility with other CPUs, you should use -march. Speaking of 
which...that really depends. "amd64" means a lot of CPUs, including AMD 
and Intel models. What's your CPU?

According to [1], you should set -march=k8 for AMD CPUs (non-EM64T) 
and -march=nocona for Intel ones (EM64T). But, for AMD athlon64 X2, you 
can also use -march=athlon64. [2] is a good reference, IMHO.

If you want to optimize further, the forums have lots of threads devoted 
to CFLAGS optimization.

[1] http://www.gentoo.org/doc/en/gentoo-amd64-faq.xml#cflags
[2] http://gentoo-wiki.com/Safe_Cflags
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Re: [gentoo-amd64] Correct -march in make.conf

[Mark Haney]

Etaoin Shrdlu wrote:
> On Monday 18 December 2006 19:06, Mark Haney wrote:
> 
>> I've been using -mcpu since I started using gentoo, but have been
>> noticing the '-mcpu is deprecated etc.' messages when updating.  Being
>> the paranoid I am, I'd like to get rid of those, but haven't found the
>> correct option to use for -march.  Is it the same as -mcpu?  Or what's
>> the correct one for amd64?
> 
> You can use -mtune in place of -mcpu. If you don't need binary 
> compatibility with other CPUs, you should use -march. Speaking of 
> which...that really depends. "amd64" means a lot of CPUs, including AMD 
> and Intel models. What's your CPU?
> 
> According to [1], you should set -march=k8 for AMD CPUs (non-EM64T) 
> and -march=nocona for Intel ones (EM64T). But, for AMD athlon64 X2, you 
> can also use -march=athlon64. [2] is a good reference, IMHO.
> 
> If you want to optimize further, the forums have lots of threads devoted 
> to CFLAGS optimization.
> 
> [1] http://www.gentoo.org/doc/en/gentoo-amd64-faq.xml#cflags
> [2] http://gentoo-wiki.com/Safe_Cflags

All the suggestions I have received have been great.  As for my CPU it's
a standard Athlon64 sitting in a Compaq laptop.  Nothing particularly
outside the norm.

Thanks again for all the answers.



-- 
Ita erat quando hic adveni.

Mark Haney
Sr. Systems Administrator
ERC Broadband
(828) 350-2415
-- 
gentoo-amd64@gentoo.org mailing list