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Date:      Sun, 28 Sep 2003 12:54:06 -0500
From:      Dan Nelson <dnelson@allantgroup.com>
To:        Alex de Kruijff <freebsd@akruijff.dds.nl>
Cc:        freebsd-questions@freebsd.org
Subject:   Re: Q: Compiles for wrong processor and it still worked
Message-ID:  <20030928175405.GF25442@dan.emsphone.com>
In-Reply-To: <20030928173759.GA16713@dds.nl>
References:  <20030928173759.GA16713@dds.nl>

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In the last episode (Sep 28), Alex de Kruijff said:
> I have compiles my world sources for the PIII processors. I have
> recently discoverd that i have a number of PII processors. The compiled
> code for PIII still works on them. I'm ammazed. :o Can anybody explain why?
> 
> I include this in to /etc/make.conf

686, pII, p3, and p4 are all basically the same instruction set.  the
later versions add more MMX and SEE operations, and I don't believe gcc
generates code that uses them.  The different arch flags probably just
change the instruction timing tables.

-- 
	Dan Nelson
	dnelson@allantgroup.com



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