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Date: Tue, 07 Nov 2000 17:01:57 -0700
From: "Jeff V. Merkey" <jmerkey@timpanogas.org>
Organization: TRG, Inc.
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To: Jeff Garzik <jgarzik@mandrakesoft.com>
CC: kernel@kvack.org, Martin Josefsson <gandalf@wlug.westbo.se>,
        Tigran Aivazian <tigran@veritas.com>, Anil kumar <anils_r@yahoo.com>,
        linux-kernel@vger.kernel.org
Subject: Re: Installing kernel 2.4
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Jeff Garzik wrote:
> 
> Jeff Merkey wrote:
> > here are tests for all this in the feature flags for intel and
> > non-intel CPUs like AMD -- including MTRR settings.  All of this could
> > be dynamic.  Here's some code that does this, and it's similiar to
> > NetWare.  It detexts CPU type, feature flags, special instructions,
> > etc.  All of this on x86 could be dynamically detected.
> 
> Jeff, I think you miss the point that 100% dynamic detection comes with
> a penalty over the current system.
> 
> Using CONFIG_M586 enables us to compile with Pentium-specific
> instructions, and eliminate any code specific to 386's or 486's.  This
> includes inlining Pentium-specific code into drivers and the core kernel
> where possible, for the maximum possible performance.  Your scheme
> doesn't work because of all the inlined code, nor does it support
> maximum performance code on all processors without massive code bloat...
> 
> You do bring up a good point though.  Users compile their own kernels to
> get the advantages I describe above.  Vendors, on the other hand, must
> compile one-size-fits-all generic kernels.  Your expertise and
> assistance would definitely benefit this case.
> 

We need a format that allow multiple executable segments to be combined
in a single executable and the loader have enough smarts to grab the
right one based on architecture.  two options:

1.  extend gcc to support this or rearragne linux into segments based on
code type
2.  Use PE.

Jeff

> One change I would like to make in 2.5.x along these lines -- the Alpha
> AXP port allow one to define either CONFIG_ALPHA_GENERIC -- support all
> processors/machines -- or CONFIG_ALPHA_$MYMACHINE.  It would be nice to
> follow that model for x86 too.  Currently, when I select CONFIG_M586, I
> get code for 686, etc.  There is no way to simply say "Pentium and
> nothing else".
> 
>         Jeff
> 
> --
> Jeff Garzik             | "When I do this, my computer freezes."
> Building 1024           |          -user
> MandrakeSoft            | "Don't do that."
>                         |          -level 1
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