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Re: missing memory and the mystery of MTRRs

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  Re: missing memory and the mystery of MTRRs Charlie Gibbs <cgibbs@surfnaked.ca> - 2021-02-14 21:40 +0100
    Re: missing memory and the mystery of MTRRs Charles Curley <charlescurley@charlescurley.com> - 2021-02-14 22:50 +0100
    Re: missing memory and the mystery of MTRRs Andrei POPESCU <andreimpopescu@gmail.com> - 2021-02-15 09:20 +0100
      Re: missing memory and the mystery of MTRRs Henrique de Moraes Holschuh <hmh@debian.org> - 2021-02-16 17:20 +0100
    Re: missing memory and the mystery of MTRRs rhkramer@gmail.com - 2021-02-15 13:30 +0100

#231718 — Re: missing memory and the mystery of MTRRs

[Sorry about the lack of threading - I read this list via its Usenet 
group so I can't reply to the list.]

On Sun Feb 14 11:58:31 2021 "Alexander V. Makartsev" <avbetev@gmail.com>
wrote:

 > On Sat Feb 13 16:44:34 2021 Charlie Gibbs <cgibbs@surfnaked.ca> wrote:
 >
 >> [    0.012080] WARNING: BIOS bug: CPU MTRRs don't cover all of
 >> memory, losing 4800MB of RAM.

<snip>

 >> Is there some sort of HOWTO that covers this stuff?  Where do I go
 >> from here?
 >
 > Even if there is a "HOWTO" to learn some information, are you capable
 > of unpacking, disassembling and patching BIOS of your motherboard and
 > reassemble working image of it to flash into ROM?

I was afraid it might come down to that.

 > I suggest you to fiddle with BIOS settings first. Search for anything
 > that looks like memory related, like "Memory Hole", or something.
 > If this trial and error approach won't help, you can update your BIOS
 > as a last resort.
 > Since your motherboard is pretty old, and Intel has dropped all
 > support for Legacy products, you can't download BIOS updates from
 > Intel official source anymore. [1]
 > But you can still find them on archive sites. [2] I can't vouch for
 > this  site, but it looks like genuine BIOS update from Intel.
 > I have to warn you about security risks, because there could be a
 > small possibility, it was patched with malware, but considering this
 > BIOS is for an ancient hardware I have my doubts and personally I
 > would take the risk.
 > And besides, there are no other options.

Well, there is one other option: replace the motherboard.  Given that
it's becoming increasingly cranky on boot, that might be the way to go.
We had a power outage the other day, and when I tried to restart the
machine it would get past the Grub screen, then sit there forever with
a screen that was blank except for a blinking cursor.  It took about
half a dozen tries before it finally continued the boot process from
there.  I seem to recall that this happened last time we had a power
outage too.  For now I think I'll just keep my backups current, and
come the day it decides not to boot anymore I'll just replace it.

Thanks for the hints.

-- 
/~\  Charlie Gibbs                  |  Microsoft is a dictatorship.
\ /  <cgibbs@kltpzyxm.invalid>      |  Apple is a cult.
  X   I'm really at ac.dekanfrus     |  Linux is anarchy.
/ \  if you read it the right way.  |  Pick your poison.

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#231720

On Sun, 14 Feb 2021 12:22:25 -0800
Charlie Gibbs <cgibbs@surfnaked.ca> wrote:

> We had a power outage the other day, and when I tried to restart the
> machine it would get past the Grub screen, then sit there forever with
> a screen that was blank except for a blinking cursor.  It took about
> half a dozen tries before it finally continued the boot process from
> there.  I seem to recall that this happened last time we had a power
> outage too.  For now I think I'll just keep my backups current, and
> come the day it decides not to boot anymore I'll just replace it.

You might also look into an uninterruptable power supply (UPS). These
include surge protection. There are several daemons available in Debian
that support one or more UPS vendors, e.g. apcupsd.

-- 
Does anybody read signatures any more?

https://charlescurley.com
https://charlescurley.com/blog/

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#231723

[Multipart message — attachments visible in raw view] — view raw

On Du, 14 feb 21, 12:22:25, Charlie Gibbs wrote:
> 
> Well, there is one other option: replace the motherboard.  Given that
> it's becoming increasingly cranky on boot, that might be the way to go.
> We had a power outage the other day, and when I tried to restart the
> machine it would get past the Grub screen, then sit there forever with
> a screen that was blank except for a blinking cursor.  It took about
> half a dozen tries before it finally continued the boot process from
> there.  I seem to recall that this happened last time we had a power
> outage too.  For now I think I'll just keep my backups current, and
> come the day it decides not to boot anymore I'll just replace it.

Can you reproduce this by powering off and disconnecting the mains?

You could try replacing the BIOS battery.

Kind regards,
Andrei
-- 
http://wiki.debian.org/FAQsFromDebianUser

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#231755

On Mon, 15 Feb 2021, Andrei POPESCU wrote:
> On Du, 14 feb 21, 12:22:25, Charlie Gibbs wrote:
> > We had a power outage the other day, and when I tried to restart the
> > machine it would get past the Grub screen, then sit there forever with
> > a screen that was blank except for a blinking cursor.  It took about
> > half a dozen tries before it finally continued the boot process from
> > there.  I seem to recall that this happened last time we had a power
> > outage too.  For now I think I'll just keep my backups current, and
> > come the day it decides not to boot anymore I'll just replace it.
> 
> Can you reproduce this by powering off and disconnecting the mains?
> 
> You could try replacing the BIOS battery.

Indeed.  It would explain weird BIOS settings creeping in (sometimes not
visible on BIOS menus), and causing weird malfunctions.

Replacing the NVRAM battery and a full BIOS settings reset (which will
clean up the entire config nvram even if the BIOS build does not expose
some settings as menus) typically fixes these.

-- 
  Henrique Holschuh

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#231724

On Sunday, February 14, 2021 03:22:25 PM Charlie Gibbs wrote:
> Well, there is one other option: replace the motherboard.  Given that
> it's becoming increasingly cranky on boot, that might be the way to go.
> We had a power outage the other day, and when I tried to restart the
> machine it would get past the Grub screen, then sit there forever with
> a screen that was blank except for a blinking cursor.  It took about
> half a dozen tries before it finally continued the boot process from
> there.  

Becaise GRUB is one one of your disks, I'd be suspicious of the disks before 
(or at least as much as) the motherboard.

> I seem to recall that this happened last time we had a power
> outage too.  For now I think I'll just keep my backups current, and
> come the day it decides not to boot anymore I'll just replace it.

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