re: WIndowsNT "snoop" cycles before doing DMA

[Alan Deikman <Alan.Deikman@znyx.com>]

>From: "Lange, Michael" <lange@dvs.de>
>Subject:  WIndowsNT "snoop" cycles before doing DMA

>> BUT : we observed that BEFORE the DMA hardware engine is running there
>> are single
>>          cycle Read/Writes every 4 kByte (= page size of Windows NT)
>> exactly to the physical
>>          memory address to be used as the destination address for the
>> DMA.

I don't believe that this is Microsoft doing this.  At least I
have never heard of this from any of our driver writers.  
However, device probing DOES seem to be popular with the 
SCSI/RAID device driver crowd.  We have observed this behavior
from one RAID controller card that was doing this from the
ROM firmware at POST time.  The purpose of it is unknown.
Also, I recall recently that we were having problems in a
Linux system  (my memory might not be exactly right
on this) where the driver for the Adaptec SCSI chip was 
also doing bus-probing.  We took out the driver (the 
system didn't need it) and the probing went away.  

I suggest you carefully inventory what ROM firmware is 
running, and what device drivers in your NT system.  
Theres some smart Microsoft guys on this list, and I
bet they can confirm that it's not their code doing it.

Regards,
-----------------------
  Alan.Deikman@znyx.com