[vfio-users] intel_iommu=on breaks audio on haswell cpu

[socnetid]

Le anonymous faker,

I am also having a similar issue. I have an i5 4690K Haswell (Devil's
Canyon). I use HDMI out to an HD TV from an ASRock Z97 Extreme6
motherboard. After adding "intel_iommu=on" to GRUB, updating and
rebooting, Debian Testing appears to see it but no audio is emitted fro
m the TV speakers.

I am successfully passing through my Nvidia GTX 970 dedicated ASUS
STRIX PCI card to Windows 8.1 Pro via the PCI/GPU Passthrough method
with both graphics and audio in order to play games unavailable to
Linux.

I would like to use my iGPU for Linux with sound over HDMI while
running the Linux host and the Windows VM client. The "igfx=off" switch
does not appear to be a solution since you have stated that it breaks
iommu for this purpose.

I may have missed something but I suppose that to date a solution is
not actively being sought as it may be impossible for this integrated
issue to be resolved on Haswell based CPU's.

It is the only observable problem to an otherwise perfect use case for
Haswell class, Linux based, Windows game play without dual booting. The
intention wasn't to use Windows full time on Linux as I might as well
just use Windows alone. I don't want to use Windows as my primary OS
but contain it within a VM until a better option for gaming becomes
available.

Despite this, I am extremely impressed and appreciative of Alex and
everyone involved for making this possible. Thank you for this
interesting, useful and very cool innovation.


    From: Le anonymous faker <etfaker bestmail ws>
    To: Colin Godsey <crgodsey gmail com>
    Cc: vfio-users redhat com
    Subject: Re: [vfio-users] intel_iommu=on breaks audio on haswell
cpu
    Date: Tue, 24 May 2016 06:56:06 +0200

.... "intel_iommu=on,igfx_off" means that HDMI audio output will work
but PCI passthrough won't.

I already tried this, with lots of outputs:
https://bbs.archlinux.org/viewtopic.php?id=204460

Thanks !

2016-05-21 19:09 GMT+02:00 Colin Godsey <crgodsey gmail com>:

    intel_iommu=on,igfx_off should work

    On Sat, May 21, 2016 at 11:01 AM Le anonymous faker <etfaker
bestmail ws> wrote:

        Lė Patrick 🚗👔☀ Sneida:
        Hey there,

        just recently I discovered that the kernel command line
"intel_iommu=on" breaks audio output (glitching/freezing output via
laptop speakers, no output at all via HDMI) for owners of haswell
cpu's.
        Changing it to "intel_iommu=igfx_off" resolved the issue.
        How ever, in order to use PCI passthrough of my NVIDIA Card to
VirtualBox, I need the parameter "intel_immou=on" ?

        Is there a way to fix the audio glitching with intel_iommu=on ?

        Is there a way to get nvidia pci passthrough to working without
intel_iommu=on (e.g. intel_iommu=igfx_off) ?

        Lots of outputs and other users reporting:
        https://bbs.archlinux.org/viewtopic.php?id=204460
        https:
//bugzilla.kernel.org/show_bug.cgi?id=60769

        Kind regards !_______________________________________________
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