Re: SMP (IO-APIC??) weirdness (CONFIRMED) (fwd)

Linux Lists (lists@cyclades.com)
Fri, 9 Jul 1999 14:12:30 -0700 (PDT)


Hello,

Could someone pls comment on this issue ?? I'd really appreciate it.

Just to "refresh" our minds, this is the hardware:

- Dell PowerEdge 2300, Dual P-II/400, 256MB RAM
- Cyclom-8Yo ISA card (a multiport serial card)

Thanks in advance.

Regards,
Ivan

---------- Forwarded message ----------
Date: Thu, 8 Jul 1999 16:26:55 -0700 (PDT)
From: Linux Lists <lists@cyclades.com>
To: Jos van de Ven <josvdv@sci.kun.nl>
Cc: Linux Kernel List <linux-kernel@vger.rutgers.edu>,
Linux SMP List <linux-smp@vger.rutgers.edu>
Subject: Re: SMP (IO-APIC??) weirdness (CONFIRMED)

Hello, Jos!

On Thu, 8 Jul 1999, Jos van de Ven wrote:
>
> > In this case, /proc/interrupts does not see any interrupts being generated
> > by the Cyclom-Y card, even though the IRQ is registered by the driver
> > (i.e., it's listed in /proc/interrupts, yet with '0' interrrupts
> > generated).
> I like to see that /proc/interrupts still, if possible.

Ok, here it is:

CPU0 CPU1
0: 28041 27516 IO-APIC-edge timer
1: 0 2 IO-APIC-edge keyboard
2: 0 0 XT-PIC cascade
8: 1 1 IO-APIC-edge rtc
9: 0 0 IO-APIC-edge Cyclom-Y
12: 0 0 IO-APIC-edge PS/2 Mouse
13: 1 0 XT-PIC fpu
16: 28556 28630 IO-APIC-level aic7xxx, aic7xxx
20: 1279 1339 IO-APIC-level SMC EPIC/100
21: 1357 1442 IO-APIC-level SMC EPIC/100
NMI: 0
ERR: 0

The Cyclom-Y allocated the IRQ as IO-APIC-edge (that's what you probably
wanted to know, isn't it?!).

> > If kernel is compiled as UP, the Cyclom-Y works fine, using the _same_ IRQ
> > that it tried to use on the SMP kernel.
> Hmm. We can do that another way. I sent you a patch, with which you can enable
> the use of IO-APIC-Level ipv Edge or XT-PIC per interrupt. It's a simple patch,
> but it has already prover to be useful.

Tried the patch on the client's system. The results are as follows:

- 'ioapic_level=9' : makes no difference (i.e., problem is still the same)
- 'xtpci=9' : problem is solved (i.e., interrupts are seen by the system)

I'm thinking about notifying Dell about this, but I'd like to hear from
the Linux SMP / APIC people first. Could anyone explain with "slightly"
more details what's going on here?? Is there a way to fix this in
software? Is it useful to contact Dell about this ??

TIA and Regards,
Ivan Passos

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