Relaxable RMRR kernel parameter for broken platforms

[bugtracker@fischbytes.de]

Hi there,

I came here today to ask if there are any plans regarding the implementation 
of a "relaxed RMRR" kernel parameter to aid using IOMMU on broken platforms 
such as the ProLiant Series by Hewlett Packard Enterprise. To everyone not 
aware of the issue;

Certain vendors that are under the assumption that standards are for jerks and 
Intel's specifications are a loose optional guideline have implemented RMRR in 
such a way that every PCI device is marked as reserved and therefore cannot be 
passed through to a virtual machine. This issue has been very well documented 
by some people that have a lot more experience than I do at the below linked 
resource. I was hoping that the kernel devs could implement the Relaxed RMRR 
option as an optional kernel parameter to use on these bugged platforms as 
that would re-enable or rather enable a lot of broken servers for the first 
time ever to use PCIe Passthrough. I can verify the issue exists on a HPE 
DL360e Gen8 with trying to passthrough a GPU to a KVM/QEMU machine.

Link to fix: https://github.com/Aterfax/relax-intel-rmrr

Furthermore, since I am not a developer and wouldn't claim that I am competent 
enough to decide whether or not implementing this patch would present an issue 
in terms of stability or security, I was hoping that you could evaluate the 
situation. I can verify the pre-built packages for the Proxmox Linux 
environment fix the issue and behave identical in function to other systems 
that ignore RMRR completely, such as VMWare ESXi.

Thanks alot in advance, you implementing this patch would really mean a lot, 
since the hardware manufacturers just don't seem to care for fixing up this, 
erm, mess.

Skali S.