Subject: Re: should we be using -m486?
To: Max Bell <mbell@europa.com>
From: nathaniel daw <ta-ndd1@columbia.edu>
List: port-i386
Date: 12/14/1995 20:39:57
On Thu, 14 Dec 1995, Max Bell wrote:

> It would seem rather obvious to me that using the -m486 flag will allow
> the compiler to include 486-specific instructions in the resulting code.
> If a given program still works on a 386 it is due to luck, and should
> not be depended on.

Well, except, according to the manpage:

       -m486

       -mno-486
              Control whether or not code is optimized for a  486
              instead  of  an 386.  Code generated for a 486 will
              run on a 386 and vice versa.


> Since the 386 systems are the slowest of the x86 machines, requiring them
> to recompile in order to be sure the code will work would be rather rude.

There's a point there, but on the other hand it doesn't seem sensible to 
cripple ourselves as more and more people move to newer platforms. I 
guess the answer would involve balancing (a) does it cause tremendous 
gains on a pentium, (b) does it make a crippling difference a 386, and
(c) how many people are still using 386s anyway compared to 486, p5? I 
suspect the answers to (a) and (b) are no; I have no idea about c.

nd