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Date:      Wed, 31 Jan 2007 16:59:09 +0000
From:      "Abdullah Ibn Hamad Al-Marri" <almarrie@gmail.com>
To:        "Jorn Argelo" <jorn@wcborstel.com>
Cc:        Scott Killen <salkillen@internode.on.net>, freebsd-questions@freebsd.org
Subject:   Re: gcc compiler cputype, prescott or nocona confusion
Message-ID:  <499c70c0701310859g6bfca627t794e8b6a5580820c@mail.gmail.com>
In-Reply-To: <209e855bb68d64550ec4e384b3983664@mail.wcborstel.com>
References:  <200701312340.38593.salkillen@internode.on.net> <209e855bb68d64550ec4e384b3983664@mail.wcborstel.com>

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On 1/31/07, Jorn Argelo <jorn@wcborstel.com> wrote:
>
>
> On Wed, 31 Jan 2007 23:40:38 +1100, Scott Killen <salkillen@internode.on.net> wrote:
> > Hi,
> >
> > When recompiling the world or kernel in FreeBSD i386 Rel 6.1 with,
> >
> > "# make buildworld"
> > or
> > "# make buildkernel KERNCONF=MYSMPCONF"
> >
> > (or building anything anything else for that matter), even though I have
> > "CPUTYPE?=nocona" set in my "/etc/make.conf" file the compiler seems to
> > head
> > back to a default of  "-march=prescott" when compiling many of the
> > functions
> > on a Dual Xeon 3.6g (nocona) machine!
> >
> > This doesn't happen when compiling for other machine types, I've tried it
> > on a
> > Dual PentiumPro, Dual PII, Dual PIII setting the CPUTYPE to the correct
> > cpu
> > type and the -march sticks to the assigned cpu type through all operations
> > and produces nice quick optimized code.
> >
> > Why is this so?
> >
> > Is it because the "nocona" machine type optimization refers to the EMT64
> > technology and thus is rejected when compiling for i386 targets rather
> > than
> > amd64 or emt64 targets and Gcc rejects it?
>
> That's right. AFAIK the Nocona core is a prescott with EM64T support (feel free to correct me if I am wrong). Basically you have an i386 version of FreeBSD, and with EM64T instructions enabled GCC will build a 64-bit version of FreeBSD. I think that's the reason it switches back to prescott.
>
> Jorn
>
> >
> > Regards
> > Scott K

For the record I used "nocona" with my dual xeon emt64 2.8 GHz and it
broke my kernel.

-- 
Regards,

-Abdullah Ibn Hamad Al-Marri
Arab Portal
http://www.WeArab.Net/



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