STI, HLT in acpi_cpu_idle_c1

[Don Bowman]

From: Matthew Dillon [mailto:dillon at apollo.backplane.com]
>     It is unlikely that the emulator is at fault, though I 
> suppose it is
>     a possibility.   It is more likely that there are simply no normal
>     interrupts being made pending and so your HLT is never waking up.
> 
>     If inserting a NOP makes things magically work, then the 
> emulator is
>     broken and needs to be fixed.  You can't have a NOP in 
> there for real
>     because you blow up the interlock.

I only have the emulator on there because of the bug,
not the other way around :)
The boards without the emulator are the ones that hang,
that's why i dragged it out.
I am definitely generating other interrupts
(e.g. serial, trying to drop into db, hardclock), but
all for naught. If I generate an NMI, it hangs
sending the stop ipi to the other processors, so
they don't receive that either. The core that i then
generate shows them in 'hlt'.

I'm wondering about some of the specification updates
for the Xeon, e.g. P72 of 
http://developer.intel.com/design/Xeon/specupdt/24967839.pdf
seems kind of esoteric, but...

--don