Ask HN: Anybody enabled IOMMU on AWS metal servers?

[scrubs]

As per: Section 17.9: https://doc.dpdk.org/guides/nics/ena.html

and https://github.com/amzn/amzn-drivers/tree/master/userspace/dpdk/enav2-vfio-patch

Enabling IOMMU on i3 or c5 metal instances is as easy as adding "iommu=1 intel_iommu=on" to /etc/default/grub followed by update-grub, reboot.

I can't get this to work. Every time I update grub and reboot I cannot reconnect via ssh. Also EC2 console fails to get good status.

My config:

* Ubuntu 20.04 stock AWS AMI x86 64-bit

* i3.metal (spot)

Less importantly but also of interest on IOMMU:

If one is on bare metal is IOMMU really needed? Seems like no if one is not using HVM. Unsafe IOMMU mode could work.

Are there any performance advantages to IOMMU? Again as far as I can see, no.

Thank you

[mikewarot]

The only reason to enable an IOMMU is if you have applications in user mode that are directly accessing hardware and you want to protect the system from them. It looks like it is disabled by default, so if you enable it, you're likely to have to do quite a bit of debugging to get it to go, which is problematic for off site hardware.

[scrubs]

I got this sorted out. I will post a URL with instructions Sun/Mon.