Re: [2/2] ACPI: report "Module Device" support via _OSI

[Bjorn Helgaas <bjorn.helgaas@hp.com>]

On Thursday 20 April 2006 02:33, Kenji Kaneshige wrote:
> Bjorn Helgaas wrote:
> > On Wednesday 19 April 2006 00:34, Kenji Kaneshige wrote:
> > 
> >>I have a question. The ACPI container driver can be build as a
> >>kernel module. Should _OSI("Module Device") returns TRUE even
> >>when container driver module is not loaded? (Typically, _OSI is
> >>evaluated at _INI time, I think. So container driver module is
> >>not loaded at _OSI("Module Device") time anyway.)
> > 
> > 
> > Good question.  I think _OSI("Module Device") should return
> > true even if the container driver isn't loaded.
> > 
> > Do you think that's a bad idea?
> > 
> > I think it's OK if the namespace contains container devices
> > that we ignore until the driver is loaded.  Someday, the
> > presence of those devices should be enough to cause udev
> > to load the driver automatically.  But for now, I think we
> > have to do it manually.
> >
> 
> I see. I think you are right.
> 
> But now, I'm wondering why ACPI firmware needs _OSI("Module
> Device") because I think module devices in the namespace will
> be ignored by the OS if it doesn't support "Module Device"...

I think the intent is that firmware might choose to expose
some devices differently (either using module devices or
not) depending on whether the OS supports module devices.
I guess the firmware might use the result of _OSI("Module
Device") to decide which table to load.