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RE: 'machine check while in PAL mode'?

>halt code = 7
>machine check while in PAL mode
>PC = 18400

I had this problem on my LX164 when I decided to try the SRM console. 
Evidently either SRM or the hardware is buggy.  I have had 
much, much better luck with AlphaBIOS than with SRM.

As to what "Machine check while in PAL mode" means:
PAL is Priveleged Architecture Library, and implements various
low-level functionality, like fault vectors, interrupts, etc.  PAL is
a chip mode that is supposed to run atomically (i.e.
non-interruptable).  If an event that triggers PAL mode occurs when
already executing in PAL mode, you get this machine check.  My sources
tell me (I work at Compaq in the Alpha group) that there's not much
left at this point to try to debug what happened.  My machine is a
Pyxis Rev B board, and has known bugs (in the chipset) relating to
DMA.  I'd be interested to hear the source of your LX; I've been led
to believe that revenue-quality boards should not have this problem.

When I had this problem, I turned off various kernel options (IDE DMA
especially) and that seemed to restrict the problem to soundcard
access.  At that point I gave up and went back to AlphaBIOS and MILO,
and have been running happily ever since.  Evidently the MILO PALcode
is different enough to not trigger the problem.


Doug Larrick  doug@ties.org  doug.larrick@compaq.com  AIM: DougLarick

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