Glad to see this bug report isn't completely dead. Can confirm too that the problem still exists with kernel 4.2.0-27-generic with the same motherboard as per the original bug report.
The attached is a recent extract from dmesg outputs...I use vfio passthrough for GFX on a Windows guest. You can see from the timestamps that I start the guest at 21:02:44 and at around 21:26:07 I get some DMAR faults pertain to device at 00:02.0. This device is the Intel IGD... lspci -s 00:02.0 00:02.0 VGA compatible controller: Intel Corporation Xeon E3-1200 v3/4th Gen Core Processor Integrated Graphics Controller (rev 06) ...not sure if this is related to the HDMI audio or not. What I can say is that I have to boot the host with "intel_iommu=on". If I change this to =on,igfx_off then my syslog fills with constant complaints about DMAR for another device I use in passthrough which works perfectly with =on, this device is a DVB-S2 device. If I use =igfx_off this stops IOMMU so I can not longer passthrough PCI devices but presto the HDMI audio now works?! ** Attachment added: "dmesg-extract-intel_iommu-on" https://bugs.launchpad.net/ubuntu/+source/alsa-driver/+bug/1428121/+attachment/4573164/+files/dmesg-extract-intel_iommu-on -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to alsa-driver in Ubuntu. https://bugs.launchpad.net/bugs/1428121 Title: Intel HDMI Audio not working with IOMMU enabled Status in ALSA driver: Unknown Status in alsa-driver package in Ubuntu: Confirmed Bug description: New ASRock Z97 Extreme 6 motherboard with an Intel i7 4790S and an Nvidia GTX 650. Host uses Intel IGD for video and HDMI audio out. When I pass kernel flags 'intel_iommu=on' or 'intel_iommu=on,igfx_on' HDMI audio no longer functions although the device and modules seem to load and I cannot locate any error messages. In this configuration IOMMU functions as expected and I can successfully pass the Nvidia card through to a KVM guest using VFIO. As per this (https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1223840) bug report and the linked bugzilla thread I attempted to use kernel flag 'intel_iommu=on,igfx_off'. This resolves the HDMI audio out but breaks IOMMU as in VGA pass through generates DMA errors. I'm running from a clean installation of 14.10 with no modifications to the kernel or kvm, qemu, libvirt or virt-manager. In either scenario above the analogue audio out continues to function, I haven't tested the optical out as I have no hardware to do so. ProblemType: Bug DistroRelease: Ubuntu 14.10 Package: linux-image-3.16.0-31-generic 3.16.0-31.41 ProcVersionSignature: Ubuntu 3.16.0-31.41-generic 3.16.7-ckt5 Uname: Linux 3.16.0-31-generic x86_64 ApportVersion: 2.14.7-0ubuntu8.2 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC2: kelvin 3468 F.... pulseaudio /dev/snd/controlC3: kelvin 3468 F.... pulseaudio /dev/snd/controlC0: kelvin 3468 F.... pulseaudio /dev/snd/controlC1: kelvin 3468 F.... pulseaudio CurrentDesktop: Unity Date: Wed Mar 4 12:53:17 2015 HibernationDevice: RESUME=UUID=4d35060a-85c4-45fd-9f8e-530491588931 InstallationDate: Installed on 2015-02-26 (5 days ago) InstallationMedia: Ubuntu-Server 14.10 "Utopic Unicorn" - Release amd64 (20141022.2) MachineType: To Be Filled By O.E.M. To Be Filled By O.E.M. ProcFB: 0 inteldrmfb ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.16.0-31-generic.efi.signed root=UUID=4914f227-6bb0-40bb-a781-9ad7111a996f ro intremap=no_x2apic_optout intel_iommu=on,forcedac pci-stub.ids=10de:11c8,10de:0e0b nomdmonddf nomdmonisw RelatedPackageVersions: linux-restricted-modules-3.16.0-31-generic N/A linux-backports-modules-3.16.0-31-generic N/A linux-firmware 1.138.1 RfKill: SourcePackage: linux UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 12/17/2014 dmi.bios.vendor: American Megatrends Inc. dmi.bios.version: P1.70 dmi.board.name: Z97 Extreme6 dmi.board.vendor: ASRock dmi.chassis.asset.tag: To Be Filled By O.E.M. dmi.chassis.type: 3 dmi.chassis.vendor: To Be Filled By O.E.M. dmi.chassis.version: To Be Filled By O.E.M. dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrP1.70:bd12/17/2014:svnToBeFilledByO.E.M.:pnToBeFilledByO.E.M.:pvrToBeFilledByO.E.M.:rvnASRock:rnZ97Extreme6:rvr:cvnToBeFilledByO.E.M.:ct3:cvrToBeFilledByO.E.M.: dmi.product.name: To Be Filled By O.E.M. dmi.product.version: To Be Filled By O.E.M. dmi.sys.vendor: To Be Filled By O.E.M. To manage notifications about this bug go to: https://bugs.launchpad.net/alsa-driver/+bug/1428121/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : [email protected] Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp
