bhyve/passthru for Intel dGPU (ARC A380)?

Happy new year all.

I've been using bhyve happily for a year or two now, multiple machines with
VT-d running happily passing SAS cards and USB cards into VMs.

I've reached the point where I want to pass a GPU in for accelerated
encoding/decoding/etc (scrypted, tdarr, jellyfin). I picked up an Intel ARC
A380, as it's encoders/decoders are pretty decent for my use case - I'd
also seen that there had been success with people using the iGPU's in Intel
CPUs successfully.

Unfortunately after attaching the GPUs PCI device to ppt, and attempting to
start a VM with it attached, I'm greated by an error that seems to focus on
iGPUs?

/usr/sbin/bhyve -A -H -w -u -S -c 2 -m 8G -l com1,/dev/nmdm202B -l
bootrom,/usr/local/share/uefi-firmware/BHYVE_UEFI.fd,/usr/local/var/cache/bmd/k8s-worker-3.vars
-s 0,hostbridge -s 1,lpc -s 2,nvme,/dev/zvol/vm/k8s-worker-3 -s
3,ahci-cd,/mnt/vm/isos/ubuntu-24.04-live-server-amd64.iso -s
5,virtio-net,tap9 -s 4,passthru,4/0/0 -s
6,fbuf,tcp=0.0.0.0:6007,w=1280,h=720,vga=io
-s 7,xhci,tablet test
bhyve: Warning: Unable to reuse host address of Graphics Stolen Memory. GPU
passthrough might not work properly.
bhyve: gvt_d_setup_opregion: Invalid OpRegion signature
bhyve: gvt_d_init: Unable to setup OpRegion
Device emulation initialization error: No such file or directory

The machine is an AMD EPYC 7343 on a ASRock ROMED8-2T, it has a dedicated
onboard GPU (attached to the BMC), which the BIOS is configured to
encourage operating systems to use as the primary display - and sure enough
the loader and BSD console are presented through the BMCs ASPEED AST2500.

Digging through the freebsd source tree, it appears that that pci_gvt-d.c
is responsible for this, if it's Intel and a Display then attempt the set
up of graphics memory.
https://github.com/freebsd/freebsd-src/blob/b662ca1d6cd82044c6cb79075e1830b97594bef3/usr.sbin/bhyve/amd64/pci_gvt-d.c#L44

Has anyone experimented with this? Can I just patch this out, rebuild bhyve
and expect a chance of success?

Cheers,

P.
-- 
*Peter Wood*
peter@alastria.net