On Tuesday, February 6, 2018 6:59:34 AM CET Alex Hung wrote: > On Fri, Feb 2, 2018 at 3:25 AM, Rafael J. Wysocki <rjw@xxxxxxxxxxxxx> wrote: > > On Thursday, February 1, 2018 9:07:59 AM CET Alex Hung wrote: > >> 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. > > > > OK, so why does the firmware define the link objects in the namespace then? > > > >> Do you have other comments about this patch or concerns that I can work > >> with firmware engineers? > > > > It looks to me that there are some PCI interrupt link objects in the > > namespace without _PRS and which aren't pointed to by any _PRT entries. > > > > If so, what are they useful for then? > > The LNKA~LNKD used in Name(PK00) are used when PIC mode is used, ex. > _PIC(0). I see. OK, in that case I'd just change the log level of the message to "debug", and use acpi_handle_debug() for printing it for that matter. -- 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
