Andre Derrick Balsa wrote:
>
> Rafael R. Reilova wrote:
> >
> > or there is no way to get a
> > division by zero on the kernel (Maybe this is why I don't get the kernel
> > ops, yet my 686MX rev.3 TSC does stop when SOH is enabled.)
>
> Humm, just a small question: I have noticed that the oops were triggered
> by having a network daemon (usually innd) calling the kernel for
> timestamping of TCP packets. Do you have your Linux machine connected to
> a network, or is it stand-alone?
> >
Hmmm, now things begin to make sense. I _did_ notice strage behavior when
connected to the internet through ppp. Most of the time my box is
standalone, but when connected I can make the connection slow down to a
crawl (even timeout and get disconnected) by enabling the SOH (at least on
2.1.101, AYK the default now is not to use the do_fast_timeoffset on
Cyrixes). Disabling the SOH would suddenly bring all connections back to
life. Guess all those timers in the IP layer get very confused. Perhaps
if I didn't get disconnected, the kernel would eventually Oops. OTOH, if
nobody is using timestamping then no Oops (duh!).
This Cyrix thing has been dragging on for a while now. Someone metioned
that it may be possible to do something on the line of,
if (APM || TSC_QUIRK)
Save current TSC
do halt (or call the APM routine if APM compiled in)
if (APM || TSC_QUIRK) {
Calculate TSC error from the RTC or sys. timer
Fix the TSC
}
In fact, think I remember a patch flying around (if so, could the author
please email me a copy). Now the question is, are those top bits of the
TSC writtable? Again the Cyrix docs say that executing a WRMSR $10 with
DX:AX will do, (the instruction is priviledged so kernel hacking required
to test).
This might fix the APM problem too, but is kind of a bad hack, and might
not work on all processors (Pentiums I believe will not write to the top
32-bits of the TSC). Also, it introduces a slight latency when comming out
of a halt which people without the TSC problem or APM will not want in
their kernels (CONFIG_TSC_QUIRKS anyone).
Cheers,
-- Rafael
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