On Mon, Nov 25, 2013 at 10:43:27AM -0700, Al Stone wrote:
On 11/25/2013 08:30 AM, Matthew Garrett wrote:
Is ACPI_REDUCED_HARDWARE supposed to indicate support for the reduced hardware profile, or that the platform *only* implements the reduced hardware profile?
From what I can see in ACPICA, ACPI_REDUCED_HARDWARE indicates the platform *only* implements the reduced hardware profile. This *seems* to be consistent with the specification -- see 3.11.1, second bullet, for example:
Ok, so a kernel built without ACPI_REDUCED_HARDWARE would still support the reduced hardware profile?
...if by "not supported" one takes that to mean "does not exist when compiled." I can look at the ACPICA code again, just the same; perhaps there is some reasonable way to at least select one or the other at boot as the first step, and then allow switching between modes as a later step.
I don't think you'd ever want to switch after init time. There's a flag in the FADT that indicates whether a system is implementing the reduced hardware profile or not.