Messages in this thread | | | Date | Tue, 11 May 1999 15:24:47 +0200 | From | Harald Koenig <> | Subject | Re: Oops assist... |
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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 ^^^^^ ^^^^^
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