GPE handler livelock

[Nate Lawson]

John Baldwin wrote:
> np.  Btw, on another note, I've finally tracked down the weird hangs my laptop 
> has on updated HEAD to something in the GPE handling related to updates to 
> ACPI in the past year.  I'm still digging, but you can look at 
> www.freebsd.org/~jhb/gpe/ and use the modified schedgraph.py there on the 
> ktr5.out to see what happens when my laptop stops running userland processes.  
> It appears to be spending all its time running a GPE handler for a thermal 
> event.

Thanks for digging into this.  I reviewed this and am trying to figure
out why the _L00 handler never completes.  It keeps getting preempted by
the next one.  To help track this down, try removing these two lines
from the _L00 method and recompile your ASL:

    Acquire (\_TZ.C173, 0xFFFF)
    ...
    Release (\_TZ.C173)

For others who have this problem, instructions on how to recompile and
load your custom ASL can be found here (11.16.4 and 5):
http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/acpi-debug.html

> My asl is at the same URL as acpi.nc6220, it's less helpful than 
> usual as HP has taken the unusual step of apparently running it through an 
> obfuscator.

Compaq's done that for years.

-Nate