[SOLVED] Unable to boot with intel_iommu=on

[Linkandzelda]

Up until now I did PCI passthrough on Arch Linux. My hardware is able to support IOMMU without any special patches or fixes. I wanted to try and see how easy it was to use proxmox to do the same thing.

I started to follow this wiki page: https://pve.proxmox.com/wiki/Pci_passthrough
Upon adding intel_iommu=on to the grub config I'm not able to boot the machine. It results in a black screen and I'm not able to see any output or connect via SSH.

All the correct options are enabled in the bios, otherwise I'd not have got this working properly on Arch previously.

My hardware:
Asus Z9PE-D8 WS
2x E5-2670

Any ideas to what I can try to resolve this?

 

[Linkandzelda]

For those wondering I was able to resolve this issue. The cause was related to a bug with the Marvell SATA controller on this motherboard. Enabling IOMMU causes any drive connected to the that controller to be unable as DMA reads fail. My boot drive happened to be connected to it resulting in the black screen right after startup.

To resolve this, an additional kernel line is needed to restore the normal operation of the drives: iommu=pt

Hopefully this helps anyone else who might be stuck in my position.