Date: Wed, 05 Aug 1998 08:58:26 -0700 From: Mike Smith <mike@smith.net.au> To: Bruce Evans <bde@zeta.org.au> Cc: meyerd1@fang.cs.sunyit.edu, phk@critter.freebsd.dk, current@FreeBSD.ORG Subject: Re: page faults and swapping Message-ID: <199808051558.IAA03275@antipodes.cdrom.com> In-Reply-To: Your message of "Wed, 05 Aug 1998 18:17:15 %2B1000." <199808050817.SAA10585@godzilla.zeta.org.au>
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> > The problem could be reproduced, but I was able to isolate a bad > >simm and that took care of my problems. Unfortunately I had memory hole > >enabled in the bios and this made it much more difficult to isolate the > >problem. The kernel's memory probe would only pick up the first 16384K. > >The MAXMEM option had to be enabled for anything more than 16384K. > > If there's any device memory in the hole, then you shouldn't be happy to > let the probe look at any memory in the hole or above. The probe may > be confused by device memory (it may think it is normal RAM), and the > probe doesn't understand any holes except the ISA one at 640K-1M, so > there is no way to probe memory above the hole without risking confusion. > > The BIOS may have protected against such problems by reporting the > extended memory size as the amount below the hole. Setting MAXMEM > may defeat this protection. Holes above 64MB would cause similar > problems even if MAXMEM is not set. Fortunately, in -current with VM86 defined this isn't an issue, as we can query BIOS functions which are able to report the hole correctly. Another reason for VM86 to become the default. -- \\ Sometimes you're ahead, \\ Mike Smith \\ sometimes you're behind. \\ mike@smith.net.au \\ The race is long, and in the \\ msmith@freebsd.org \\ end it's only with yourself. \\ msmith@cdrom.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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