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Re: 'machine check while in PAL mode'?

On Sat, Mar 04, 2000 at 02:22:36AM +0000, pmaydell@chiark.greenend.org.uk wrote:
> --------
> In debian-alpha Doug Larrick wrote:
> >Peter Maydell wrote:
> >>halt code = 7
> >>machine check while in PAL mode
> >>PC = 18400
> >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.
> Bought from GND (www.gnd.co.uk) -- I don't have the motherboard manual
> to hand but I'll try to remember to look up the model information.
> >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.
> I switched from AlphaBIOS to MILO because I want to use a serial
> console and to the best of my knowledge AlphaBIOS doesn't support that.
> (plus SRM's user interface is much nicer than AlphaBIOS's).
> Do I have some other alternative? Perhaps booting from SRM and immediately
> replacing the SRM PALcode with something else, preferably something
> for which sources are available? Alternatively can MILO be flashed
> in as a replacement for SRM altogether on these machines?

I have seen this on some of our LX164's as well.  It happens much less
often if you build the kernel without modules.  Our LX's came from DCG.


> Peter Maydell
> (knew there was a reason why they called it "alpha" :->)
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Greg Johnson                          gjohnson@physics.clarku.edu
http://physics.clarku.edu/~gjohnson            finger for PGP key

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