svn commit: r233249 - head/sys/amd64/acpica

[Jung-uk Kim]

On Thursday 22 March 2012 07:48 am, John Baldwin wrote:
> On Thursday, March 22, 2012 5:32:59 am Andriy Gapon wrote:
> > on 21/03/2012 21:02 Jung-uk Kim said the following:
> > > On Wednesday 21 March 2012 01:57 pm, Andriy Gapon wrote:
> > >> on 21/03/2012 19:41 Jung-uk Kim said the following:
> > >>> I am well aware of the problem.  In fact, that's why I had to
> > >>> merge ACPICA 20120320 rather quickly, which added a new flag
> > >>> to not execute _GTS method.  Both _GTS and _BFS are turned
> > >>> off by default.  You can control them with a new tunable
> > >>> "debug.acpi.sleep_flags" if you want.
> > >>
> > >> But the bug still has to be fixed, right?
> > >> Even if it takes a non-default sysctl value to give the bug a
> > >> chance.
> > >
> > > Ideally, yes.  However, I am not so sure if we can call it a
> > > "bug" because AcpiEnterSleepState() must be called with
> > > interrupt disabled and there is no way to change that API
> > > without breaking other OSes. We can only work around it locally
> > > or persuade upstream to find a better way to do this in ACPICA
> > > itself.  Either way, it will be pretty hackish. :-(
> >
> > I see.  Thank you.
> > Maybe the code could be somehow tricked into using M_NOWAIT in
> > this
>
> context...
>
> That still wouldn't be good enough.  We don't want to try to
> acquire any regular mutexes either (we can't safely block to let
> the lock owner run, or the lock owner might be a suspended thread
> on another CPU, etc.).  The only proper way to fix this would be to
> use pre-allocated storage in this particular case, but given that
> Windows doesn't invoke these methods on suspend/resume, it's
> doubtful that we will ever need to do so.

FYI, I filed an upstream PR to track this issue:

http://acpica.org/bugzilla/show_bug.cgi?id=950

Jung-uk Kim