*BSD News Article 17847


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From: raeburn@athena.mit.edu (Ken Raeburn)
Newsgroups: comp.os.386bsd.bugs
Subject: Re: kernel writes to user space (was Re: Nethack)
Date: 2 Jul 1993 01:15:05 GMT
Organization: Cygnus Support, Cambridge MA
Lines: 18
Message-ID: <RAEBURN.93Jul1211447@cambridge.cygnus.com>
References: <20bfrm$le7@pdq.coe.montana.edu> <C990xF.43n@sneaky.lonestar.org>
	<1993Jun29.181749.5833@fcom.cc.utah.edu>
	<20qqgu$dj@werple.apana.org.au> <1993Jun30.022629.24466@uvm.edu>
	<C9GMzD.B6@veda.is>
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In-reply-to: adam@veda.is's message of 1 Jul 93 00:35:22 GMT

In article <C9GMzD.B6@veda.is> adam@veda.is (Adam David) writes:

  wollman@trantor.emba.uvm.edu (Garrett Wollman) writes:

  >Isn't there a flag bit you can turn on on a *4*86, which tells the MMU
  >to behave in a sane manner?  If so, then perhaps someone ought to
  >write code to take advantage of this, triggered by defined(i486) &&
  >!defined(i386).

  i486 is a superset of i386, so it does not make much sense to define i486
  without also defining i386. Therefore defined(i486) should be enough of a
  test.

That doesn't distinguish between a build for a machine that *will*
have a 486 (and therefore doesn't need the 386 version) and a build of
a generic kernel for machines that *might* have 486s (and therefore
might want to take advantage of it if it does, but still might have to
support the 386).  I'd suggest a separate "486-only" flag.