> 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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