ahc reports lots of pci parity errors

Michael Havens bmike1 at vei.net
Sat May 22 15:48:18 PDT 2004


Hey buddy, did you ever resolve the data parity error issue? While 
investigating your free-bsd list I discovered another person  had encountered 
the same problem (see 1- below). Their solution seems to implicate  an ISA 
card. However, I found a reason and a solution at the following address:
orange.kame.net/dev/cvsweb.cgi/kame/freebsd5/ sys/dev/aic7xxx/
aic7xxx_pci.c?rev=1.1.1.2
*
	 * Disable PCI parity error checking.  Users typically
	 * do this to work around broken PCI chipsets that get
	 * the parity timing wrong and thus generate lots of spurious
	 * errors.  The chip only allows us to disable *all* parity
	 * error reporting when doing this, so CIO bus, scb ram, and
	 * scratch ram parity errors will be ignored too.
	 */

PLUG, so my question to you  is how does one disable parity error reporting 
and what could be detrimental in doing this?

As I was reviewing this mailing I took heed of the last message at thebottom:

	On lot of motherboards I've seen some PCI slots share a single 
	interrupt. I don't know if this is the case with your motherboard, 
	but if it is then I can certainly imagine it causing problems.

So I will save this message and restart and see if any devices have the same 
IRQ......

I opened BIOS  and found ACPI IRQ = 10; however that could be changed to 9 or 
11. I also found IRQ 10 assigned to PCI/ISA PnP but found I could change that 
to Legacy ISA (which I did).....and restarted the computer...... and got the 
same error. (did I do this right?)

So now I will unplug the ISA card..... this isn't the problem.

I now am certain that the data parity timing is wrong.
-- 
<:-)Mike(-:>

1-
Hiho! :-)

I'm getting lots of those, but my system is stable.

ahc0: PCI error Interrupt at seqaddr = 0xffff
ahc0: Signaled a Target Abort
ahc0: WARNING WARNING WARNING WARNING
ahc0: Too many PCI parity errors observed as a target.
ahc0: Some device on this bus is generating bad parity.
ahc0: This is an error *observed by*, not *generated by*, this
controller.
ahc0: PCI parity error checking has been disabled.
ahc0: WARNING WARNING WARNING WARNING
ahc0: PCI error Interrupt at seqaddr = 0xffff


I'm running 5.2.1-RELEASE with ACPI disabled.

Usually I'm getting one or two errors over a period of  two weeks or
longer, but since I'm using my old ISA Creative SB32, I'm getting lots
in a very short period of time.

What could cause that? A broken PCI-card? Motherboard? 

TIA :-)

Bye
Marc

----------------------------

Maybe a problem with the ISA-to-PCI bridge on your motherboard, or else a 
timing problem.  You aren't playing with the bus frequency multipliers, 
overclocking, or anything like that, right?

Dump the ISA soundcard for a PCI one and you'll probably do better...

-- 
-Chuck

----------------------------

> Maybe a problem with the ISA-to-PCI bridge on your motherboard, or
> else a timing problem.  You aren't playing with the bus frequency
> multipliers, overclocking, or anything like that, right?

Nope, nothing at all. It's a Tyan Thunder X with two PII-Xeon 450Mhz,
nothing overclocked.

> Dump the ISA soundcard for a PCI one and you'll probably do better...

Yep, just removed it.

But as i wrote above I still get sporadic parity errors even without
that old isa-card.

Any idea what might cause those?

Bye
Marc

----------------------------

Hmm, I narrowed it down.

It starts going havoc if there are more than 4 PCI cards inserted. If
the fifth card is a PCI card, I get lots of errors and even lockups
really soon, if the fifth card is an ISA card, i get less errors and
I've only encountered one lockup until now.

I've two NICs and two graphic-cards (all PCI), ide-controller onboard
and scsi controller onboard.

Is this behaviour something that might be expected with this kind of
setup or is it a sign of defective/failing hardware (buggy/broken
southbridge, as Chuck suggested)?

TIA :-)

Bye
Marc

----------------------------

On lot of motherboards I've seen some PCI slots share a single interrupt. I 
don't know if this is the case with your motherboard, but if it is then I can 
certainly imagine it causing problems.
--
Toomas Aas






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