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From: Heikki Suonsivu <hsu@clinet.fi>
Received: (hsu@localhost) by katiska.clinet.fi (8.6.10/8.6.4) id PAA02603; Mon, 13 Mar 1995 15:39:42 +0200
Date: Mon, 13 Mar 1995 15:39:42 +0200
Message-Id: <199503131339.PAA02603@katiska.clinet.fi>
To: freebsd-bugs@freefall.cdrom.com
In-reply-to: Heikki Suonsivu's message of 12 Mar 1995 18:24:29 +0200
Subject: NCR SCSI fails
Organization: Helsinki University of Technology, Otaniemi, Finland
Sender: bugs-owner@FreeBSD.org
Precedence: bulk


   This failed on our P60 motherboard with NCR SCSI, is this a broken
   motherboard, configuration problem or something else?

More workout; This "cache test" fails even if both internal and external
caches are disabled.  I also went through all BIOS settings and disabled
everything which even distantly hinted into any caching or buffering, to no
avail.  So, it seems that this cache test can't be quite correct?  The only
oddity I can see is that the code doesn't first check what is sees in the
"read-only" address before it tries to write 0xffffffff into it?

   /*==========================================================
   **
   **
   **	Test the pci bus snoop logic :-(
   **
   **	Has to be called with interrupts disabled.
   **
   **
   **==========================================================
   */

   #ifndef NCR_IOMAPPED
   static int ncr_regtest (struct ncb* np)
   {
	   register volatile u_long data, *addr;
	   /*
	   **	ncr registers may NOT be cached.
	   **	write 0xffffffff to a read only register area,
	   **	and try to read it back.
	   */
	   addr = (u_long*) &np->reg->nc_dstat;
	   data = 0xffffffff;
	   *addr= data;
	   data = *addr;
   #if 1
	   if (data == 0xffffffff) {
   #else
	   if ((data & 0xe2f0fffd) != 0x02000080) {
   #endif
		   printf ("CACHE TEST FAILED: reg dstat-sstat2 readback %x.\n",
			   (unsigned) data);
		   return (0x10);
	   };
	   return (0);
   }
   #endif


   -- 
   Heikki Suonsivu, T{ysikuu 10 C 83/02210 Espoo/FINLAND,
   hsu@cs.hut.fi  home +358-0-8031121 work -4513377 fax -4555276  riippu SN