VT-d, iommu, dmar failing - xen troubleshooting - thinkpad e15 gen 2

User Support Hardware Issues
,
1

Please help troubleshoot/fix.

Xen boot (xl dmesg) will eventually display: `Failed to parse ACPI DMAR. Disabling VT-d). This will disable iommu support.

It’s a Lenovo E15 Gen 2. The BIOS is the latest and I already ran the lenovo critical update to it. BIOS settings are also correct.

It’s strange because I moved the SSD from one laptop to the other and both are exact same model/gen, the only different is the first was ram 8GB, this is 16GB.

I have added to the grub iommu=1 and tried other parameters, but they are not doing the trick.

Also on:

https://forums.lenovo.com/t5/ThinkPad-X-Series-Laptops/VT-d-iommu-dmar-failing-xen-qubesos-troubleshooting-thinkpad-e15-gen-2/m-p/10034906?page=1#10131751

2

Solved!

Issue was, contradicting my notes “Kernel DMA protection” must be on (and apparently is supported by Xen/Qubes).

Attention is to one must boot the machine twice to “stick”. Counter-intuitive.

Four days of struggle are over, awkward. Fun thing was to use acpidump, acpixtract and iasl (cheers poddingue at xcp-ng).

1 Like