mjg59 at srcf.ucam.org
Thu Nov 21 11:56:03 EST 2013
On Mon, Nov 18, 2013 at 01:42:32PM -0500, Jon Masters wrote:
> Starting a new thread with a question. Suppose for a moment that ACPI
> is the way of the future and that there is, in fact, already a three
> year story behind this that will come out in due course. What could
> be done to make things smoother /going forward/? Could we articulate a
> series of useful asks that would help with moving forward with ACPI?
> For example, it is clear that there needs to be more involvement in
> the standardization of ACPI (this is why we initiated the governance
> model change of ACPI several years ago that has taken this long to
> resolve with everyone involved in that) and we want to get more ARM
> kernel folks involved. But what else? Blank slate. What do we need to
> make ACPI a success here?
Define what ARM vendors actually want from ACPI. Most ACPI functionality
is entirely invisible to userspace. The enterprise-level functionality
in the DSDT is all vendor-specific and exists primarily because of a
Windows design decision, so there's no obvious requirement to do
things the same way this time around. The other tables are meaningful,
but also don't require the DSDT or a runtime ACPI interpreter.
The obvious compromise implementation would be to continue using DT for
device discovery and just use ACPI as a means for providing static data.
This would be a strict violation of the ACPI spec as it currently
stands, but the only real change would be making the DSDT optional. Why
would that not satisfy vendor requirements?
 Microsoft specced a mechanism for gluing WMI into ACPI, which means
you can pretty much implement all your vendor magic in userspace rather
than having to write a driver and get it signed
Matthew Garrett | mjg59 at srcf.ucam.org
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