> That there could be a real error in that code surprises me, since
> Peter really knows what he's doing, even if that low in the
> hardware, there are undocumented interactions that even Intel's
> errata doesn't seem to know about.

Turns out the workaround is to use DISABLE_PG_G.

Two things made me try this.  One: In his commit of pmap.c
and locore.s on 7/12 7:56 Peter had this to say:

 |- Try and fix some very bogus PG_G and PG_PS interactions that were bad
 |  enough to cause vm86 bios calls to break.  vm86 depended on our existing
 |New option:  DISABLE_PG_G - In case I missed something.

Two: cvs diff -r1.336 -r1.337 of i386/pmap.c showes that
#ifdef SMP was changed to ifndef DISABLE_PG_G and it is in
here that pfeflag is set (pfeflag is what guards the code at
the crash site!).

>         set boot_ddb

Didn't do this.

>         set boot_gdb

Did this.  I though the above two were mutually exclusive options.
boot_ddb should be renamed to start_in_debugger or something.

Though boot -d is what I was really looking for.

> higher/later code, the root cause is catually in locore.s.  Happy
> bug hunt!  ;^).

Thanks but looks like I easily escaped from the hunt this
time :-)

-- bakul

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