Date: Tue, 1 Jun 1999 11:23:48 -0500 From: "Mike Avery" <mavery@mail.otherwhen.com> To: freebsd-questions@FreeBSD.ORG Subject: Re: Memory hole ????? Message-ID: <199906011635.LAA16153@hostigos.otherwhen.com> In-Reply-To: <Pine.BSF.4.05.9906011005470.43461-100000@neptune.twrol.com> References: <00d401beac36$c6cd3020$3c29a8c0@tci.rdo>
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On 1 Jun 99, at 10:11, James R. Shrenk wrote:
> I have to agree. Change the RAM (to one 64 MB module if you can). Sadly,
> memory that comes from two different manufacturers is not always
> compatible. I've had similar experience particularly with newer memory
> chips labeled PC100 that actually weren't, and I've also had worse
> problems with smaller memory chips in some 486 boxes that I have.
I think we're missing the point. Christian asked..
>> can anyone help me ? strange things happen when I try to
>> install freeBSD 3.1 on my system (P100, FIC Board with 64MB RAM,
Award
>> BIOS from '95). After putting the 2nd install disk in, the computer
>> hangs. when I reduce my memory to 32 MB, everything goes fine. I also
>> checked the other 32 MB and there weren't any problems. As I want to
>> use my full 64 MB RAM, I tried to find any BIOS settings for the
>> memory. So, when I enable the 'Memory Hole At 15MB Addr.', I can
>> install and boot BSD without problems. Could anyone please explain me
>> what this setting means ? And is there another way to get rid of the
>> problem because with this setting I cannot boot my other operating
>> systems ?
When he enabled the hole at 16 meg setting, the system worked, and
he wanted to know what that setting means.
<gross simplification warning>
The hole at 16 meg setting is an anachronism that has it's roots back
to the days of the 8088, and the brain dead way memory has been
allocated on Intel systems. The upper 380 some odd k of the 1 meg
address space was, and is, used for various I/O devices, video
boards, and BIOS. (After all, 640k ought to be enough for anyone,
huh?)
When CPU's came along that allowed more memory, and ram came
along that was larger, the question of how to map the memory
became an issue. Some people cache anything they can in the upper
memory area to improve performance. Others map the memory in
that region so it becomes available above the other installed memory.
Of course, there's another barrier at the 16 meg point that was
passed when we went from the 386 to the 486. And then memory
got larger again. So, what do you do with the memory when you have
more than 16 megs? In some memory mapping schemes, you wind up
with a hole at the 16 meg barrier. Some OS's seem to prefer that.
Some puke when they see it. Others work either way. And
sometimes it depends on the motherboard and BIOS combined with
the OS. And sometimes things seem to work until you push 'em.
For Win95 and NT machines I use PowerQuest's DriveImage Pro.
And some of my clients started complaining that they were running
out of ram when imaging small disks (just a few gigs), even when they
had lots of ram. A check revealed that the hole at 16 megs was
enabled on each of those machines. Turning off the hole at 16 megs
allowed DriveImage Pro to work, and had no unpleasant side effects.
</gross simplification warning>
All in all, if it works, I'd use it. However, I'd also target that
motherboard and it's ram for my next upgrade/replacement cycle
just on general principles. I'd either replace it, or when another
machine is upgraded, I'd put the displaced components into that
machine.
Mike
======================================================================
Mike Avery MAvery@mail.otherwhen.com
(409)-842-2942 (work)
ICQ: 16241692
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A Randomly Selected Thought For The Day:
Newsflash: Microsoft announces Visual Edlin for Windows.
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