Edit: my system’s chipset & cpu: Z390 / 9900k.
My MacOS vm will not boot if I place my RX 580 into the PCH x4 slot, even though the card appears to be completely isolated in its own IOMMU group like so:
IOMMU Group 13
03:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Ellesmere [Radeon RX 470/480] (rev e7)
03:00.1 Audio device: Advanced Micro Devices, Inc. [AMD/ATI] Ellesmere HDMI Audio [Radeon RX 470/480 / 570/580/590]
However, it does work after I add pci=nommconf to my grub cmdline, but causes another issue, namely that it places it into the same iommu group as my windows boot drive:
IOMMU Group 6
00:1b.0 PCI bridge: Intel Corporation Cannon Lake PCH PCI Express Root Port (rev f0)
00:1b.4 PCI bridge: Intel Corporation Cannon Lake PCH PCI Express Root Port (rev f0)
02:00.0 Non-Volatile memory controller: Samsung Electronics Co Ltd NVMe SSD Controller SM981/PM981
03:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Ellesmere [Radeon RX 470/480] (rev e7)
03:00.1 Audio device: Advanced Micro Devices, Inc. [AMD/ATI] Ellesmere HDMI Audio [Radeon RX 470/480 / 570/580/590]
Does anyone know of a way that I can keep the first set of iommu groupings but still successfully boot?