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VFIO / IOMMU in Clear Linux on AMD

#1

Hi,

I am new here, I’ve been looking all over the internet without luck. I have lots of experience with VFIO tuning, GPU Passthrough, libvirt etc. All of this on CentOS or Fedora distros.

What I would love to do is to try things on Clear Linux, and while libvirt / kvm is easy, I just can’t get IOMMU to load on my Threadripper. I don’t have an Intel machine around, so is this just a AMD issue, or does Clear Linux just not do IOMMU pt?

Or is it something I am missing?

Thanks for any help,
DJ

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#2

Clear Linux is Intel. So this is interesting. Probably the two are related lol.

If the kernel has Intel iommu compiled in well … thatd do it

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#3

I am aware that Clear is Intel, but I thought Intel didn’t do obvious nerfs. Maybe this is a place where they just “happened” to choose to not enable it. I will recompile and test.

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#4

Your guess was right, recompiled kernel with AMD IOMMU and all worked. Atrocious performance though, I suspect due to preempt optimizations which breaks into the vms flow, as benchmarks clearly got throtteled, ran for a moment, then dropped off in perf, etc, very unstable. Didn’t have time to figure out all the tuning knobs for clear this time around.

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