On Wed, Jan 31, 2018 at 11:30 PM, Rafael J. Wysocki <rafael@xxxxxxxxxx> wrote: > 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? I meant the AE_NOT_FOUND messages still pop up when SOURCE = 0. -- Cheers, Alex Hung -- 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
