Re: [gentoo-amd64] Please suggest settings and flags in /etc/make.conf?

[Mark Knecht]

On Thu, Jan 21, 2010 at 7:05 PM, Lie Ryan <lie.1296@×××××.com> wrote:
<SNIP>
>
> You might want to add "-march=" flag to CFLAGS and CXXFLAGS. See
> http://en.gentoo-wiki.com/wiki/Safe_Cflags
>
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>>
>>
>> Thanks,
>> Mark
>>
>>
>> processor       : 3
>> vendor_id       : GenuineIntel
>> cpu family      : 6
>> model           : 37
>> model name      : Intel(R) Core(TM) i5 CPU         661  @ 3.33GHz
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>
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The Safe CFlags page doesn't list the Core i5 yet, but it does have
the Core i7 which came out a bit earlier.

For all of the following keep in mind that I don't plan on putting any
desktops or applications on this machine for a couple of days so the
compile load will be smaller until I get this worked out. I need to
read up on this Intel VGA to see if I'm going to stick with it and if
so how to get X11 to work with it.

My question is if I choose the flags shown below for the i7 am I
likely to render the machine unusable in any way? I'm not against
recompiling with other flags if these turn out to be less than optimum
at some later date, but I don't want to cause big problems.

Or, as Juan suggested I might try -march=native. However if I go that
way then I'm not sure yet whether I am supposed to turn on the
additional msse4/mcx16/msahf flags or whether =native does that
itself? I'm not using distcc so I don't think that's a problem and I
like the idea of =native for someone like me, but on the other hand I
don't generally like auto-magic sorts of solutions.

Anyway, if none of these will likely render the machine unusable and I
can do another emerge -e @system to change then it's no big deal. I
just compiled emerge -e @system - 137 packages - in a little over an
hour so doing it a few times is no big deal.

Thanks,
Mark

64 bit profile (amd64) - for >=sys-devel/gcc-4.3

CHOST="x86_64-pc-linux-gnu"
CFLAGS="-march=core2 -msse4 -mcx16 -msahf -O2 -pipe"
CXXFLAGS="${CFLAGS}"