Date: Tue, 31 Oct 2000 06:30:06 -0800 (PST) From: David Greenman <dg@root.com> To: freebsd-bugs@FreeBSD.org Subject: Re: i386/22441: pmap_growkernel() is not effective at kernel vm limit of 0xffc00000 Message-ID: <200010311430.GAA61582@freefall.freebsd.org>
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The following reply was made to PR i386/22441; it has been noted by GNATS.
From: David Greenman <dg@root.com>
To: carp@world.std.com
Cc: freebsd-gnats-submit@FreeBSD.ORG
Subject: Re: i386/22441: pmap_growkernel() is not effective at kernel vm limit of 0xffc00000
Date: Tue, 31 Oct 2000 06:23:19 -0800
>When called with a kernel vm limit of 0xffc00000, pamp_growkernel()
>does not set-up the page mapping hardware because of an overflow.
>
>In this line:
>
> addr = (addr + PAGE_SIZE * NPTEPG) & ~(PAGE_SIZE * NPTEPG - 1);
> ( Line 1403 in $FreeBSD: src/sys/i386/i386/pmap.c,v 1.250.2.5 2000/08/05 00:39:08 peter Exp $)
>
>addr + PAGE_SIZE * NPTEPG overflows to zero when addr is 0xffc00000.
I might not be understanding what you're doing exactly, but I should point
out that the alternate page table map (APTmap) starts at 0xffc00000, so I
don't see how you could ever use that area of virtual memory without serious
problems. What am I missing?
-DG
David Greenman
Co-founder, The FreeBSD Project - http://www.freebsd.org
President, TeraSolutions, Inc. - http://www.terasolutions.com
Pave the road of life with opportunities.
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