[Soekris] sc1100 TSC bug

[dzpost@dedekind.net]

I'm confused about the status of the sc1100 TSC timer bug and its
workaround.  I just installed linux on my new net4801, with a standard
2.6.18 kernel which I built for the purpose.  Based on what I'd read,
I configured scx200_hrt module so it would use the high resolution
timer as clock source instead of the TSC.

When I install the scx200_hrt module, the clock starts running really
_fast_: about 10 times normal speed.  Putting idle=poll in the kernel
command line seems to fix it (in fact it then seems to run slightly
slow, but I'm not sure about that).

When I don't install the scx200_hrt module, I see this in the log
files:

  kernel: TSC appears to be running slowly. Marking it as unstable
  kernel: Time: pit clocksource has been installed.

I haven't checked it for more than a few minutes, but the clock seems
be about as steady as with scx200_hrt and idle=poll.

What is the "pit"?  Does this mean I don't need the scx200_hrt module
at all?  My understanding is that idle=poll makes the cpu consume more
power and generate more heat, which I would rather avoid.

Can someone set the record straight on the current situation?  It
would be nice to have this information updated on the Soekris web page
as well :)

Thanks.

-David