Re: Catching NForce2 lockup with NMI watchdog

[Bill Davidsen <davidsen@tmr.com>]

On Fri, 12 Dec 2003, Maciej W. Rozycki wrote:

> On Fri, 12 Dec 2003, bill davidsen wrote:
> 
> > | In practice, assuming the MP IRQ routing information provided the BIOS has
> > | been correct (which is not always the case), prerequisites #1 and #2 have
> > | been met so far, but #3 has proved to be occasionally problematic.
> > 
> > In practice many system seem to take a good bit of guessing and testing.
> > I have an old P-II which only works with acpi=force and nmi_watchdog=2,
> > for instance.
> 
>  Well, the NMI watchdog is a side-effect feature that works by chance
> rather than by design.  So you can't really complain it doesn't work
> somewhere, although I wouldn't mind if new hardware was designed such that
> it works.  You shouldn't have to use "acpi=force" for the watchdog to work
> though and for a PII system if "nmi_watchdog=1" doesn't work, then I
> suspect a BIOS bug (set APIC_DEBUG to 1 in asm-i386/apic.h and send me the
> bootstrap log and a dump from `mptable' for a diagnosis, if interested).

Has the check to see if the BIOS is old than very recent been removed? I
used to get a message that the BIOS was too old, I believe that's what
prompted the acpi to enable the local apic. Sorrt, I've been running that
feature since 2.5.3x or so and I just carried it forward.

> 
> > It would be nice if there were a program which could poke at the
> > hardware and suggest options which might work, as in eliminating the
> > ones which can be determined not to work. Absent that trial and error
> > rule, unfortunately.
> 
>  Linux has all appropriate bits to set up hardware reasonably as long as
> BIOS provides accurate information.  The only case our code fails is when
> BIOS tells us lies and the there's little we can do about it.  Actually we
> are doing hardware manufacturers a favor we try to handle some cases at
> all -- it's the BIOS that should be fixed instead and it is software and
> it is stored in Flash memories these days, so there's no excuse.  So if
> there's a problem with running Linux because of BIOS bugs, then please
> bugger the manufacturer in the first place (and avoid the company in the
> future if they don't support Linux).
> 
>  Sometimes the NMI watchdog works in principle, but its activation leads
> to system instability -- almost always this is a symptom of buggy SMM code
> executed by the BIOS behind our back (NMIs are disabled by default in the
> SMM, but careless code may enable them by accident).

Works fine for me, system stays up for 30-40 days when I let it... I also
run softdog to catch hangs in user mode but not in the kernel. That also
works.

-- 
bill davidsen <davidsen@tmr.com>
  CTO, TMR Associates, Inc
Doing interesting things with little computers since 1979.