[comp.unix.i386] DMA

zaz@jersey (Todd Koeckeritz) (08/20/90)

I have run into a rather hard to solve problem and would appreciate
any input all you netters might have.  I have a 386 (Mylex MX Revision
1.01 25Mhz) motherboard, an Archive VP402 card controlling an Archive
150M VP tape drive and an Adaptec ACB-2322B controlling a 300M disk
all running under Xenix SysV 2.3.2.  The problem I am having is that I
can write tapes fine (never had a problem here), but sometimes when I
am reading the tapes I'll panic with a general protection fault or a
non-recoverable kernel page fault.  This will happen whether I am just
listing the files (as in tar tvf or cpio -iBtvc or even dd), dumping
everything to the bitbucket (/dev/null) or actually attempting to put
the files on disk.

I do have other devices in my system, however this is the most basic
hardware configuration in which I can dupicate the problem.  My IRQs
have all been scoped out many times (2/25, 3, 4, 5 and 7 for the tape)
and I have tried both DMA channels (1 and 3) and many of the
combinations of the above.  The I/O addr of the tape drive is 0x220
and doesn't appear to conflict with anything else.  I can cause this
to happen in single user or full up, I have beat my memory and disk to
a pulp attempting to test new configurations and isolate the problem.

To me it has boiled down to three possibilities:
1) A bug in the tape driver or Xenix, although I would expect to have
   seen some other flames about this.
2) A flakey tape controller card:  temperature appears to have some
   effect.  It happens more "reliably" if my system cabinet is on than
   when it is off.
3) A problem with the motherboard (DMA Controllers or design)

The only people I haven't talked to yet are Archive and the net.  SCO
of course wouldn't talk to me (mail or voice) to confirm or deny any
complicity, and Mylex disavowed that they had ever had a problem with
their motherboards (I have heard they did from several sources, can
anyone help to confirm or deny this ?).

Has anyone ran into a similar problem ?  Or is their a known problem
with any of the equipment I have mentioned ?  This is a last ditch
effort to solve the problem before I must go down and away while I
track Mylex and whoever else must get involved in solving the problem.

I would appreciate any guesses or new lines of thought in debugging
this situation.  E-Mail me if your answers are a little tentative.

Thanks in advance.

-- 
+-----------------------------------------------------------------------------+
|  Todd Koeckeritz        zaz@jersey                 (crash!orbit!jersey!zaz) |
|  Euler Solutions, Inc., Minneapolis, MN, USA H:(612)537-4264 W:(612)635-0088|
+-----------------------------------------------------------------------------+

bill@bilver.UUCP (Bill Vermillion) (08/21/90)

In article <1990Aug20.052225.3371@jersey> zaz@jersey.UUCP (Todd Koeckeritz) writes:
>I have run into a rather hard to solve problem and would appreciate
>any input all you netters might have.  I have a 386 (Mylex MX Revision
>1.01 25Mhz) motherboard, an Archive VP402 card controlling an Archive
>150M VP tape drive and an Adaptec ACB-2322B controlling a 300M disk
>all running under Xenix SysV 2.3.2.  The problem I am having is that I
>can write tapes fine (never had a problem here), but sometimes when I
>am reading the tapes I'll panic with a general protection fault or a
>non-recoverable kernel page fault.  This will happen whether I am just
>listing the files (as in tar tvf or cpio -iBtvc or even dd), dumping
>everything to the bitbucket (/dev/null) or actually attempting to put
>the files on disk.
 
[some details deleted - wjv]
 
>To me it has boiled down to three possibilities:
>1) A bug in the tape driver or Xenix, although I would expect to have
>   seen some other flames about this.
>2) A flakey tape controller card:  temperature appears to have some
>   effect.  It happens more "reliably" if my system cabinet is on than
>   when it is off.
>3) A problem with the motherboard (DMA Controllers or design)
 
>The only people I haven't talked to yet are Archive and the net.  SCO
>of course wouldn't talk to me (mail or voice) to confirm or deny any
>complicity, and Mylex disavowed that they had ever had a problem with
>their motherboards (I have heard they did from several sources, can
>anyone help to confirm or deny this ?).
>
>Has anyone ran into a similar problem ?  Or is their a known problem
>with any of the equipment I have mentioned ?  This is a last ditch
>effort to solve the problem before I must go down and away while I
>track Mylex and whoever else must get involved in solving the problem.

Well - I thought I must have been going crazy.  And from what you 
describe, your symptoms and my symptoms - the ONLY commond things
are SCO 2.3.2 and the '386 chip itself.

I have about 2 dozen systems I take care of.  One site has the
Maynard Maynstream drives and 12 interface cards.  The ONLY
problems I have had are with the machines running 2.3.2.  The 2.2.3
machines are fine.  The machines are IBM Model 80 MCA bus.     

I haven't had the tape read problem, as I haven't read that many.
But I get major problems with tape write.

It will either 1) stop and start counting memory as if from a cold
boot 2) just hang, 3) give me a non-recoverable page fault, or 4)
double-panic with a non-recoverable page fault.

I spent several hours on one of the machines and can make the crash
happen when I want it too.  All I have to do is write to the tape a
second time without rebooting.

From a cold start it always works, and if the tape has been
written, and the machine not rebooted, trying to write the second
time will ALWAYS crash the machine.

I talked with Maynard (now an Archive company) and they deny any
problems.

I have another machine at another site that has an AMI motherboard,
8 megs of memory, DPT caching disc controller, a Maynstream 150 meg
tape (the others are 60's) and a totaly different set of serial
ports, Specialix and not Anvils.

The IBMs are 16MHz, the AMI is 20.  All the '286's with 2.2.3 run
flawlessly as did the '386s until the change to 2.3.2.  That
required new software drivers so I immediately blamed them.

I didn't know the latter machine was crashing as it was always
turned off at night.  The second time will usually lock the machine
up, though it has been spontaneously rebooted at times.

I had been leaning toward Maynard driver problems, but this leads
me to beleive there may be something in the SCO system causing it.

I have had the same results whether using tar or CTAR.  I tried
removing the tape drivers, and found the de-install script takes
some of the base system with it - and haven't had the time to do a
total re-install.  That bug in the script led me to think Maynard,
but your problems are SO similar I am now thinking OS.

So far that's two of us with strange problems.  Any one else with
strange lockups or reboots with 2.3.2 ?

bill

-- 
Bill Vermillion - UUCP: uunet!tarpit!bilver!bill
                      : bill@bilver.UUCP

cws@janus.Quotron.com (Craig W. Shaver) (08/21/90)

In article <1990Aug20.052225.3371@jersey>, zaz@jersey (Todd Koeckeritz) writes:
> I have run into a rather hard to solve problem and would appreciate
> any input all you netters might have.  I have a 386 (Mylex MX Revision
> 1.01 25Mhz) motherboard, an Archive VP402 card controlling an Archive
> 150M VP tape drive and an Adaptec ACB-2322B controlling a 300M disk
> all running under Xenix SysV 2.3.2.  The problem I am having is that I

I have locked up an interactive unix system using my archive tape.
I have had problems using tar on this tape under esix when the
buffer count was not 10 or 100.  Cannot remember crashing the system
on esix though (rev. C).  

	mylex 386/20
	adaptec 1542b + micropolis 1684-7 + archive s150

I am not ready to blame mylex, but I think the dma could be a problem.
I believe the scsi has its own dma, and the crash can be consistently caused
by using the tape dev that is not supposed to wait for rewind.  BUT -- this
only crashed on ix, not on esix.

I have had trouble with a 60mb tape using the everex controller which should
be similar to your archive controller.  The tapes were not written properly
and tapes from another machine did not produce correct files when read.

My conclusions are that for the scsi the drivers are to blame, but for the
60mb using the qic02/24 adapter it could be the bus speed and dma problems.

	Craig W. Shaver


================================================================
Quotron Systems Inc.    | Phone: (213) 302-4247
5454 Beethoven Street   | uucp: trwrb!scgvaxd!janus!cws
Post Office Box 66914	| craig@tradr2.quotron.com
Los Angeles, CA 90066   |
================================================================

usenet@carssdf.UUCP (John Watson) (08/23/90)

I have a similar problem on a 486 card.  The card with the Intel/Zymos
80..31 80..32 2 chip set is OK (I forget the whole number).  Another
486 that has its own 128K cache using the "OPTI" chipset and an 80C206
peripheral/DMA/CMOS chip crashes whenever I use 2 dma devices at the
same time, like floppy or archive tape in combination with hard disk.
The hard disk is a 600meg ESDI with 4 Meg cacheing controller by 
Consensys (Toronto Canada).  Panic, Double Panic etc..    I am trying
things like a different 80c206, or different 80c206 vendor, Semens and
Chips & Tech. both make it.  So far I have only tried Semens.  If this
helps you good luck.  If you have related info, pls pass on.  Incedentally,
other than this minor/fatal flaw it is the fastest system I have ever seen.
This is not in the same league with 386's.

John Watson       ...!carsdf!usenet

campbell@Thalatta.COM (Bill Campbell) (08/23/90)

In article <1990Aug20.052225.3371@jersey> zaz@jersey.UUCP (Todd Koeckeritz) writes:
>I have run into a rather hard to solve problem and would appreciate
>any input all you netters might have.  I have a 386 (Mylex MX Revision
>1.01 25Mhz) motherboard, an Archive VP402 card controlling an Archive
...deleted stuff

You might try changing your monitor card.  I have a 33mhz 386
system that was running fine with one EGA card and the same
Archive tape you have.  I switched to another EGA card (Maxlogic
8-bit) and suddenly the tape wouldn't work at all :-(

I installed a different EGA (Paradise 8-bit) and all worked fine
again.

Its amazing how many times that VGA cards will mess up something
else in the system.  This is the first time I had a problem with EGA.
-- 
....microsoft--\                    Bill Campbell; Celestial Software
...uw-entropy----!thebes!camco!bill 6641 East Mercer Way
....fluke------/                    Mercer Island, Wa 98040
....hplsla----/                     (206) 232-4164

usenet@carssdf.UUCP (John Watson) (08/24/90)

Additional info on my previous posting, 486 with OPTI chipset panics on
2 or more DMA access at same time...
The board has an 82C206 chip for DMA and other functions.  The Semens chip
does not work (tried 2 with identical results) and a chip by the same number
from Chips & Technologies does work.  It appears that my problem is gone.
There is a difference between these two chips and it is not just a "minor"
timing variation.  Netters beware.           John Watson
                                           Self Employed ...

jim@applix.com (Jim Morton [ext 237]) (08/28/90)

In article <1990Aug20.052225.3371@jersey>, zaz@jersey (Todd Koeckeritz) writes:
> I have run into a rather hard to solve problem and would appreciate
> any input all you netters might have.  I have a 386 (Mylex MX Revision
> 1.01 25Mhz) motherboard, an Archive VP402 card controlling an Archive
> 150M VP tape drive and an Adaptec ACB-2322B controlling a 300M disk
> all running under Xenix SysV 2.3.2.  The problem I am having is that I
> can write tapes fine (never had a problem here), but sometimes when I
> am reading the tapes I'll panic with a general protection fault or a

I've been meaning to post the final answer to a problem I had about 6
months ago that I posted here. The above problem may or may not have the
same cause...I posted a problem with a Compuadd 320 where the system
paniced when using the floppy drive with the system cache controller on,
but worked fine with the cache controller off. After a *lot* of calls
to Compuadd, they finally admitted that their rev. of the Award BIOS did
not work with their cache controller and Xenix. They sent a Phoenix BIOS
chipset and all has been well ever since...

--
Jim Morton, APPLiX Inc., Westboro, MA
...uunet!applix!jim    jim@applix.com