Re: i386 vs. i686 Architecture

From: Robert M. Riches Jr (spamtrap42_at_verizon.net)
Date: 12/06/03 

Date: Sat, 06 Dec 2003 05:42:45 GMT

In article <pRcAb.1153$7p2.162@newsread2.news.atl.earthlink.net>, Don wrote:
> The box I installed RH9 on is a P4, so I would have assumed the install
> would have used the i686 versions of things. However, it seems like most
> applications are i386 (based on running up2date).
>
> 1) Should I be concerned that i386 versions were selected over i686?
>
> 2) Is there a way to "upgrade" to the i686 versions?
>
> 3) Did I miss something during the install? (I would assume that it should
> automatically detect the processor type.)

{Side note: It depends on which "P4" you're referring to.
Many years ago, "P4" meant the 486, which was a
not-too-major respin of the 386. Recently, "P4" means a
Pentium 4 processor (Intel's legal beagles are adamant about
the noun after the adjective, and they want TM and/or R
stuffed in there somewhere, but I don't remember where)
which is basically a post-686 microarchitecture and
instruction set. (I worked on chips roughly contemporary
with the 486 and oversaw schematic formal verification of
the first version of the Pentium 4 processor.)}

If both an i686 and i386 RPM exist, a Pentium 4 processor
should use the i686 version. If only an i386 version
exists, then it should use that. At least from Redhat,
there are only a few RPMs with an i686 version. There have
been earlier discussions on the pros and cons of using code
code compiled for i386 on a modern processor, and Google
should have them archived if you are interested.

Good luck.

Robert Riches
spamtrap42@verizon.net
(Yes, that is one of my email addresses.)

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