[Soekris] sc1100 TSC bug

[David Zelinsky]

I wrote:

> 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.

I'm still confused as to what's built into the linux-2.6.18 kernel to
deal with the timer bug.  But I want to report that running _without_
the scx200_hrt or scx200 modules installed, and _without_ the
idle=poll kernel argument, it seems to work fine.  After about 2 days,
the box has had no problem keeping sync with an ntp server.

-David