On Thu, Feb 1, 2018 at 5:39 AM, Alex Hung <alex.hung@xxxxxxxxxxxxx> wrote: > On Wed, Jan 31, 2018 at 1:20 AM, Rafael J. Wysocki <rjw@xxxxxxxxxxxxx> wrote: >> On Wednesday, January 31, 2018 6:52:19 AM CET Alex Hung wrote: >>> In recent Intel hardware the IRQs become non-configurable after BIOS >>> initializes them in PEI phase and _PRS objects are no longer included in >>> ASL. >>> >>> This is the same as "static (non-configurable) devices do not >>> specify a _PRS object" in ACPI spec. As a result, error messages >>> saying "ACPI Exception: AE_NOT_FOUND, Evaluating _PRS" are not >>> needed. >> >> That's questionable at best. >> >> The errors basically indicate that _PRT entries corresponding to these >> IRQs are messed up (because they should contain the value of 0 instead of >> a NamePath in the Source column), so we are now going to paper over bugs >> in ACPI tables as someone in the firmware land cannot be bothered with >> putting correct values into them. :-/ > > Rafael, > > Thanks for quick reply and sharing the information > > It seems static (non-configurable) devices on ACPI are discussed in > both _PRS and _PRT as below: > > 6.2.12 _PRS (Possible Resource Settings) > "... Static (non-configurable) devices do not specify a _PRS object... " > > 6.2.13 _PRT (PCI Routing Table) > "In the second model, the PCI interrupts are hardwired to specific > interrupt inputs on the interrupt controller and are not configurable. > In this case, the Source field in _PRT does not reference a device, > but instead contains the value zero, and the Source Index field > contains the global system interrupt to which the PCI interrupt is > hardwired." > > My interpretation is the both are true from ACPI's perspective, and > both should be implemented by system firmware. On this particular > system I am debugging remotely, it does the _PRS part but not _PRT, > and I will follow up with firmware engineers. OK > On the other hand, it may not be unreasonable to remove AE_NOT_FOUND > as defined in 6.2.12 in ACPI spec. I also did a code trace and it > seems that the AE_NOT_FOUND in _PRS cannot be removed by a value of > zero in Source field in _PRT. I'm not sure what you mean here. Do you mean that the code would mishandle 0 in the Source field of _PRT? -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
