lkml.org 
[lkml]   [1999]   [May]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: Oops assist...
On May 10, Richard B. Johnson wrote:

> On Mon, 10 May 1999, Stephen C. Tweedie wrote:
>
> > Hi,
> >
> > On Thu, 6 May 1999 10:54:21 -0700 (PDT), Dan Hollis
> > <goemon@sasami.anime.net> said:
> >
> > >> at least on cold power-on you first have to write something to RAM
> > >> to initialize the parity bit(s). if you try to read RAM first,
> > >> odds are 50% that the parity bit is wrong and you'll get an NMI...
>
> You don't really have to clear memory, i.e., write to it. All you
> have to do is read all of it with NMI disabled.
>
> Write 0x80 to port 0x70 to disable NMI, enable later by writing 0
> out the same port (it's the index register for the CMOS clock-chip).
> Since a read or write takes about the same time, it is usual to
> just write all memory to zeros, but it is not necessary.

why should reading memory update/set parity or ECC data ?

updating parity/ecc information can't happen for sure for every read because of
performance reasons. are there special bus/memory cycles if ecc/parity fails ?
I don't believe (at least for 8088/186/... this did _not_ happen).


>
> >
> > > Are you 100% sure about this? And what about warmboots.
> >
> > It is necessary to initialise ECC memory, yes, but the BIOS should do it
> > for you. I've only got one ECC box, but at least on that one the BIOS
> > definitely spends a while setting up the memory at boot time.
> >
>
>
> Cheers,
> Dick Johnson
> ***** FILE SYSTEM WAS MODIFIED *****
> Penguin : Linux version 2.2.6 on an i686 machine (400.59 BogoMips).
> Warning : It's hard to remain at the trailing edge of technology.
>


Harald
--
All SCSI disks will from now on ___ _____
be required to send an email notice 0--,| /OOOOOOO\
24 hours prior to complete hardware failure! <_/ / /OOOOOOOOOOO\
\ \/OOOOOOOOOOOOOOO\
\ OOOOOOOOOOOOOOOOO|//
Harald Koenig, \/\/\/\/\/\/\/\/\/
Inst.f.Theoret.Astrophysik // / \\ \
koenig@tat.physik.uni-tuebingen.de ^^^^^ ^^^^^

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.rutgers.edu
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:51    [W:0.059 / U:1.136 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site