Re: one more ACPI Error (utglobal-0125): Unknown exception code:0xFFFFFFEA [Re: 2.6.18-rc4-mm3]

[keith mannthey <kmannth@us.ibm.com>]

On Thu, 2006-09-14 at 11:01 +0800, Shaohua Li wrote:
> On Wed, 2006-09-13 at 22:51 +0800, Bjorn Helgaas wrote:
> > On Tuesday 12 September 2006 19:27, keith mannthey wrote:
> > > On Thu, 2006-09-07 at 20:27 -0600, Bjorn Helgaas wrote:
> > > > > On Thu, 2006-09-07 at 09:25 -0600, Bjorn Helgaas wrote:

> > I think that your SSDT is valid.  I can't point to a specific
> > reference in the spec, but I think the "try _HID first, then try
> > _CID" strategy is clearly the intent.  Otherwise, there would be
> > no reason to separate _HID from _CID.
> The spec actually doesn't mention PNP0C01/PNP0C02. It's hard to say this
> is valid or invalid. 

Lets work on the assumption it is valid until someone points out in a
spec that says it isn't. 

> The 'try _HID first then _CID' has another downside. It highly depends
> on the driver is loaded first and then load the device. See motherboard
> driver loads first and the mem hotplug driver isn't loaded, in this
> situation if you scan the mem hotplug device, the mechanism will fail as
> the two pass search will still bind motherboard driver to the device.
Any solution depends on the mem hotplug device being loaded.  This
doesn't appear to be _HID before _CID specific issue .  

> If you take the two pass search, I have a feeling this will make acpi
> never be able to convert Linux driver model.

I am not trying to break forward work but what I do want is a solution
to my problem. 

> If you really want to workaround the issue, I prefer have a blacklist or
> something to let ACPI not use the _CID for your device, but please don't
> mess the ACPI core itself.

My fist pass to fix the problem was I guess a hack of sorts that caused
others problems (motherboard add return != 0 on unknown devices).  I
don't want another Keith grown hack that breaks other people. 

Can you elaborate on what you think would be safe way to do what you
propose since the ACPI core (can't/won't?) be fixed? I can imagine a
couple of different ways to fix this but I would like some feedback
before I go off and work on the 3rd pass of this fix. 

1.  Make the memory device get scanned before the motherboard device
somehow.  Implicitly reorder the devices in the list. Perhaps a priority
sorted of sorts to have _HID device always before _CID devices during
the scan? 

2.  Have the motherboard device (if it finds the right acpi device type)
hook into the memory device somehow. 

3.  Some special blacklist of the motherboard device on my specific
system. 


Thanks,
  Keith