ASRock Z170 Extreme 4 with BIOS version 2.30 was motherboard #1 Gigabyte GA-Z170XP-SLI with BIOS version F5 was motherboard #2
As I initially reported, both were reporting the error involving f0:1f.0 Not surprisingly, there are no f0:xx.y devices. The closest I suppose is: 00:1f.0 ISA Bridge: Intel Corporation Sunrise Point-H LPC Controller (rev 31) At the moment, I am back on vanilla 4.6.0, and no such error messages are being reported via 'xl dmesg'. I am guessing reporting of this error was added post-4.6. Eric On Tue, Dec 1, 2015 at 9:34 PM, Tian, Kevin <kevin.t...@intel.com> wrote: > Eric, could you provide your motherboard information and as Andrew pointed > out what’s f0:1f.0? > > > > *From:* Andrew Cooper [mailto:andrew.coop...@citrix.com] > *Sent:* Sunday, November 29, 2015 6:15 AM > *To:* Eric Shelton; xen-devel; Zhang, Yang Z; Tian, Kevin; Keir Fraser; > Jan Beulich > *Subject:* Re: Skylake: VT-d and other error messages > > > > On 28/11/15 20:46, Eric Shelton wrote: > > Looking through the output of 'xl dmesg' on a Skylake system (i5-6600K), I > found a number of error messages that I do not encounter on a Haswell-based > system. I have tried two motherboards from different manufacturers, with > pretty much the same results. Below are some of the unexpected messages: > > > > Not enabling x2APIC (upon firmware request) > > ... > > mwait-idle: does not run on family 6 model 94 > > ... > > [VT-D] iommu.c:875: iommu_fault_status: Primary Pending Fault > > [VT-D] INTR-REMAP: Request device [0000:f0:1f.0] fault index 0, iommu reg > = ffff82c000201000 > > (on motherboard 1) [VT-D] INTR-REMAP: reason 22 - Present field in the > IRTE entry is clear > > (on motherboard 2) [VT-D] INTR-REMAP: reason 25 - Blocked a compatibility > format interrupt request > > > > This leads to a few questions: > > 1) Is there some reason x2APIC should not be enabled on Skylake? What > consequence, if any, is there not having x2APIC enabled? > > > In this case, the firmware has set the x2apic opt-out bit in the DMAR > table, indicating that Xen should not use x2apic. > > You might find an option in your BIOS to undo this; there have been enough > errata in the past in this area that I would expect it to be a tweakable. > > x2apic is the extension to xapic, which permits more than 255 cpus. So > long as you don't have that many, there isn't a specific problem with > missing x2apic mode. > > > 2) Should mwait-idle be available on Skylake? > > > We probably need to resync the mwait driver with Linux. It is whitelisted > on known cpu model numbers. > > > 3) What about the IOMMU errors on Skylake - are they a concern? > > > Yes. > > In both cases, PCI device f0:1f.0 is misconfigured or misbehaving. > > On motherboard 1, it is delivering an interrupt for which no remapping > entry has been set up. > > On motherboard 2, it is delivering an compatibility-format interrupt, as > opposed to a remapable-format interrupt. > > For motherboard 2, Xen should disallow such a configuration. Either > interrupt remapping is enabled and all devices should be configured to > issue remmapable interrupts, or interrupt remapping is disabled and > everything should be configured to issue compatibility-format interrupts. > > Either way, diagnosing the problem here starts with identifying what > f0:1f.0 is. > > ~Andrew >
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