Re: PSA: Clock drift and pkgin

["Maciej W. Rozycki" <macro%orcam.me.uk@localhost>]

On Tue, 19 Dec 2023, Johnny Billquist wrote:

> >   Which is exactly why I keep writing we ought not be doing this (if we do)
> > and should rely solely on the high-resolution timer for timekeeping.
> 
> No real disagreement there, except if you mean something like the DS1287 then
> I'm not sure I agree on the definition of "high resolution timer".

 The DS1287 is an example source of the timer interrupt with some systems 
where a high-resolution timer has to provided separately, just as with the 
4000/60.  By no means I find the DS1287 itself a high-resolution timer.

> >   Conversely what I have been concerned with is incorrect operation with
> > actual hardware, and then this specific one.
> 
> Did anyone actually report results running on a 4000/60?

 Me, earlier on in this thread.

 I do have a 4000/90 too, but it suffers from an issue I yet need to debug 
where it ever boots NetBSD 9 from local storage only once.  Then the OS 
corrupts itself somehow in storage such that any subsequent attempt to 
boot causes the firmware to fail:

>>> boot

-DKA200
  83 BOOT SYS
-DKA200
  83 BOOT SYS
-DKA200
  83 BOOT SYS
[...]

and storage has to be reimaged from the original to boot again.

 So I switched to using my 4000/60 until the cause of the failure with the 
4000/90 has been identified, as I find the latter system pretty much 
unusable in this situation.  The very same system image works just fine 
and boots repeatedly with the 4000/60.

> Personally, I've been
> running on a 4000/90, where time is not working well. But that one would be
> depending on the ICR. But I haven't checked if it actually do have a proper
> ICR. Does anyone know?

 It does, implemented in the NCA.

 NB I worked with Mike Uhler (the lead designer of the NVAX in case you 
didn't know), who was the manager of our group at MIPS UK back in early 
2000s, and knowing his absolute technical insight I'd have no doubt he 
wouldn't let such an important architectural feature out of the NVAX 
microarchitecture.

  Maciej