sio: lots of silo overflows on Asus K8V with Moxa Smartio C104H/PCI

Bruce Evans bde at
Fri Apr 30 21:38:25 PDT 2004

On Fri, 30 Apr 2004, othermark wrote:

> Burkard Meyendriesch wrote:
> > ...
> > Meanwhile I plugged the Moxa board into another PCI slot of my motherboard
> > and the conflict with the ata6 interrupt seems to be solved. The silo
> > over- flows are still there.
> >
> > By the way: How should I set the BIOS parameters "PCPI 2.0 yes/no" and
> > "ACPI APIC yes/no"? Do they have anything to do with the PCI interrupt
> > behaviour?
> I had to enable APIC to get my puc supported card to work.  W/o it the
> interrupts were shared and I received a ton of silo overflows and lost data
> on line.

There must be bugs elsewhere for shared interrupts to cause lots of slo
errors.  Try my patch in other mail to avoid Giant lossage.  I forgot
to mention that a larger unwritten patch is also needed to fix sio's
interrupt priority for the shared case (all tty interrupts get the low
priority PI_TTYLOW, but most or all hardware ones should have priority
PI_TTYHIGH, and drivers that prefer to use a fast interrupt should get
priority higher than the current highest priority (PI_REALTIME).

> so try the following in your kernel and rebuild

COM_MULTIPORT is only needed for old isa-ish multiport cards.  It is
not needed for cards supported by puc, and has large overheads so it
shouldn't be used when not needed.

> options PUC_FASTINTR

This may be critical here.  But don't use it if the port is actually
shared with a device whose driver doesn't support fast interrupts.
Then it will either have no effect or will break the attachment of the
other device, depending on which device is attached first.

> device apic

He must already have this to get irq19.

"device apic" may also cause silo overflows.  See my other reply.


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