Re: Generic interface for accelerometers (AMS, HDAPS, ...)

[Vojtech Pavlik <vojtech@suse.cz>]

On Thu, Jul 06, 2006 at 11:46:04PM -0300, Henrique de Moraes Holschuh wrote:
> On Thu, 06 Jul 2006, Vojtech Pavlik wrote:
> > > >We are investigating the ACPI global lock as a way to at least get the
> > > >SMBIOS to stay away from the EC while we talk to it, but we don't know if
> > > >the entire SMBIOS firmware respects that lock.
> > > 
> > > It had better, that is exactly what the ACPI Global Lock is supposed to 
> > > prevent (concurrent access to non-sharable resources between the OS and 
> > > SMI code). The ACPI DSDT contains information on whether or not the 
> > > machine requires the Global Lock in order to access the EC or whether it 
> > > is safe to access without locking.
> >  
> > Isn't that vaild only if you actully use ACPI to access the EC? (AFAIK
> > the HDAPS driver does direct port access.)
> 
> It better be valid for any OS-side access to the EC, otherwise the ACPI
> global lock would be utterly useless.  The system vendor would have done its
> own "global-lock-like" functionality without the need for an ACPI global
> lock specification.

That's what I fear does happen on many systems.

> What is not clear to me is whether an ACPI DSDT method is on the "OS side"
> or on the "SMM side" of the ACPI global lock.

No idea, sorry.

-- 
Vojtech Pavlik
Director SuSE Labs