From owner-freebsd-hackers  Tue Jul 14 17:12:03 1998
Return-Path: <owner-freebsd-hackers@FreeBSD.ORG>
Received: (from majordom@localhost)
          by hub.freebsd.org (8.8.8/8.8.8) id RAA07923
          for freebsd-hackers-outgoing; Tue, 14 Jul 1998 17:12:03 -0700 (PDT)
          (envelope-from owner-freebsd-hackers@FreeBSD.ORG)
Received: from implode.root.com (implode.root.com [198.145.90.17])
          by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id RAA07915
          for <freebsd-hackers@FreeBSD.ORG>; Tue, 14 Jul 1998 17:12:00 -0700 (PDT)
          (envelope-from root@implode.root.com)
Received: from implode.root.com (localhost [127.0.0.1])
	by implode.root.com (8.8.5/8.8.5) with ESMTP id RAA24922;
	Tue, 14 Jul 1998 17:11:42 -0700 (PDT)
Message-Id: <199807150011.RAA24922@implode.root.com>
To: Luoqi Chen <luoqi@watermarkgroup.com>
cc: bf20761@binghamton.edu, freebsd-hackers@FreeBSD.ORG
Subject: Re: Wrong comment in pmap_bootstrap() about virtual_avail? 
In-reply-to: Your message of "Tue, 14 Jul 1998 18:59:52 EDT."
             <199807142259.SAA28732@lor.watermarkgroup.com> 
From: David Greenman <dg@root.com>
Reply-To: dg@root.com
Date: Tue, 14 Jul 1998 17:11:42 -0700
Sender: owner-freebsd-hackers@FreeBSD.ORG
Precedence: bulk
X-Loop: FreeBSD.ORG

>> In file i386/pmap.c, routine pmap_bootstrap(), I find the following
>> comment:
>> 
>> "XXX  The calculation of virtual_avail is wrong.  It's NKPT*PAGE_SIZE too
>> large.  It should be instead be correctly calculated in locore.s and not
>> based on 'first'(which is a physical address, not a virtual address, for
>> the start of unused physical memory)..."

   I wrote the comment. The word "wrong" above doesn't mean that it is wrong
in the sense that there is a bug in the code. It means only that, from an
architectural perspective, it should represent the actual start of the
kernel VM (after the kernel text/data/bss), and instead means something
slightly different.
   I can't help but wonder why you are looking at this code fragment...it
is highly esoteric for most anyone who intends to do development in the
FreeBSD kernel.

-DG

David Greenman
Co-founder/Principal Architect, The FreeBSD Project

To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-hackers" in the body of the message