N100 - PCE Passthrough - iGPU does get assigned an IOMMU Group
I have been trying to passthrough the iGPU of an N100 to try and get Frigate and Plex hardware acceleration. My Frigate is currently running as an add-on Home Assistant - might move it over in the future but for now, that's how it sits. On my old computer, I was able to passthrough the iGPU. But I am struggling a lot this time round.
I have followed various guides to no success. My problem seems to be that the iGPU does not get assigned an IOMMU group - as you can see here.
Has anybody had any success with passing through the iGPU of an N100?
My GRUB looks like this:
GRUB_DEFAULT=0 GRUB_TIMEOUT=5 GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian` GRUB_CMDLINE_LINUX_DEFAULT="quiet intel_iommu=on iommu=pt intel_iommu=igfx_off i915.enable_guc=3 i915.max_vfs=7 initcall_blacklist=sysfb_init pcie_aspm=off" GRUB_CMDLINE_LINUX="intel_iommu=on intel_iommu=igfx_off iommu=pt vfio_iommu_type1.allow_unsafe_interrupts=1 kvm.ignore_msrs=1" GRUB_TERMINAL=console
/etc/modules looks like this:
# /etc/modules: kernel modules to load at boot time. # # This file contains the names of kernel modules that should be loaded # at boot time, one per line. Lines beginning with "#" are ignored. # Modules required for PCI passthrough vfio vfio_iommu_type1 vfio_pci vfio_virqfd # Generated by sensors-detect on Fri Mar 1 21:10:48 2024 # Chip drivers coretemp # Generated by sensors-detect on Fri Mar 1 21:18:45 2024 # Chip drivers coretemp
My /etc/kernel/cmdline looks like this:
intel_iommu=on
The GPU is definitely recognized.
00:00.0 Host bridge: Intel Corporation Device 461c 00:02.0 VGA compatible controller: Intel Corporation Alder Lake-N [UHD Graphics] 00:02.1 VGA compatible controller: Intel Corporation Alder Lake-N [UHD Graphics] 00:02.2 VGA compatible controller: Intel Corporation Alder Lake-N [UHD Graphics] 00:02.3 VGA compatible controller: Intel Corporation Alder Lake-N [UHD Graphics] 00:02.4 VGA compatible controller: Intel Corporation Alder Lake-N [UHD Graphics] 00:02.5 VGA compatible controller: Intel Corporation Alder Lake-N [UHD Graphics] 00:02.6 VGA compatible controller: Intel Corporation Alder Lake-N [UHD Graphics] 00:02.7 VGA compatible controller: Intel Corporation Alder Lake-N [UHD Graphics] 00:0d.0 USB controller: Intel Corporation Device 464e 00:14.0 USB controller: Intel Corporation Alder Lake-N PCH USB 3.2 xHCI Host Controller 00:14.2 RAM memory: Intel Corporation Alder Lake-N PCH Shared SRAM 00:16.0 Communication controller: Intel Corporation Alder Lake-N PCH HECI Controller 00:17.0 SATA controller: Intel Corporation Device 54d3 00:1c.0 PCI bridge: Intel Corporation Device 54b8 00:1c.1 PCI bridge: Intel Corporation Device 54b9 00:1c.2 PCI bridge: Intel Corporation Device 54ba 00:1c.3 PCI bridge: Intel Corporation Device 54bb 00:1c.6 PCI bridge: Intel Corporation Device 54be 00:1f.0 ISA bridge: Intel Corporation Alder Lake-N PCH eSPI Controller 00:1f.3 Multimedia audio controller: Intel Corporation Alder Lake-N PCH High Definition Audio Controller 00:1f.4 SMBus: Intel Corporation Device 54a3 00:1f.5 Serial bus controller: Intel Corporation Device 54a4 01:00.0 Ethernet controller: Intel Corporation Ethernet Controller I226-V (rev 04) 02:00.0 Ethernet controller: Intel Corporation Ethernet Controller I226-V (rev 04) 03:00.0 Ethernet controller: Intel Corporation Ethernet Controller I226-V (rev 04) 04:00.0 Ethernet controller: Intel Corporation Ethernet Controller I226-V (rev 04) 05:00.0 SATA controller: JMicron Technology Corp. JMB58x AHCI SATA controller
IOMMU is enabled too:
root@proxmox:~# dmesg | grep -e DMAR -e IOMMU [ 0.009090] ACPI: DMAR 0x0000000075490000 000088 (v02 INTEL EDK2 00000002 01000013) [ 0.009123] ACPI: Reserving DMAR table memory at [mem 0x75490000-0x75490087] [ 0.023831] DMAR: IOMMU enabled [ 0.023843] DMAR: Disable GFX device mapping [ 0.023904] DMAR: IOMMU enabled [ 0.023925] DMAR: Disable GFX device mapping [ 0.062253] DMAR: Host address width 39 [ 0.062254] DMAR: DRHD base: 0x000000fed90000 flags: 0x0 [ 0.062261] DMAR: dmar0: reg_base_addr fed90000 ver 4:0 cap 1c0000c40660462 ecap 29a00f0505e [ 0.062263] DMAR: DRHD base: 0x000000fed91000 flags: 0x1 [ 0.062268] DMAR: dmar1: reg_base_addr fed91000 ver 5:0 cap d2008c40660462 ecap f050da [ 0.062270] DMAR: RMRR base: 0x0000007c000000 end: 0x000000803fffff [ 0.062272] DMAR-IR: IOAPIC id 2 under DRHD base 0xfed91000 IOMMU 1 [ 0.062274] DMAR-IR: HPET id 0 under DRHD base 0xfed91000 [ 0.062275] DMAR-IR: Queued invalidation will be enabled to support x2apic and Intr-remapping. [ 0.064045] DMAR-IR: Enabled IRQ remapping in x2apic mode [ 0.286432] pci 0000:00:02.0: DMAR: Skip IOMMU disabling for graphics [ 0.369787] DMAR: No ATSR found [ 0.369788] DMAR: No SATC found [ 0.369790] DMAR: dmar1: Using Queued invalidation [ 0.370145] DMAR: Intel(R) Virtualization Technology for Directed I/O [ 11.015097] pci 0000:00:02.1: DMAR: Skip IOMMU disabling for graphics [ 11.020373] pci 0000:00:02.2: DMAR: Skip IOMMU disabling for graphics [ 11.025930] pci 0000:00:02.3: DMAR: Skip IOMMU disabling for graphics [ 11.030346] pci 0000:00:02.4: DMAR: Skip IOMMU disabling for graphics [ 11.035703] pci 0000:00:02.5: DMAR: Skip IOMMU disabling for graphics [ 11.039326] pci 0000:00:02.6: DMAR: Skip IOMMU disabling for graphics [ 11.042549] pci 0000:00:02.7: DMAR: Skip IOMMU disabling for graphics
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I use a cluster of N100 minipcs with integrated GPU pass-through without issue. You seem to be applying a couple of different configurations and have left out some information, so I will try to explain in detail some of the processes.
It used to be that you could pass-through a primary GPU to a VM and in doing so you would have to make sure the host didn't load the GPU drivers and take control of the GPU before the VM. This is when you configure IOMMU pass-through and blacklist the GPU drivers on the host. This would mean that the GPU could be passed on to just one VM, and the host would no longer have access.
With the newer chipsets like the Alder Lake N100 it is possible to use SR-IOV to generate multiple virtual GPUs (up to seven) to pass on to multiple VMs. This would also allow host device to still have access to the GPU.
You seem to be doing both configurations which isn't necessary. My suggestion would be to stick with the SR-IOV configuration.
This configuration should only require that the SR-IOV i915 driver be built for the host and that the following GRUB configuration be used
As well as the number of sriov vGPUs be configured in the sysfs.conf file.
There is a great tutorial here https://www.derekseaman.com/2023/11/proxmox-ve-8-1-windows-11-vgpu-vt-d-passthrough-with-intel-alder-lake.html
Now as for the VM getting the passed through GPU there are some considerations. First it has to be a q35 machine, it is required to have the OVMF bios. Further more when you pass the GPU it will have to be set as primary and your display set to none. The GPU that you pass also has to be a subset of the vGPUs 0000.00.20.1-7 and not the primary 0000.00.20.0 otherwise the host (proxmox) driver will crash and need to be restarted.
That being said what isn't very clear is the VM guest has to be aware of this configuration as well. If you are running a windows VM and install the ARC drivers it should be fine. If you are running a Linux VM it will need pretty much the same configuration setup as the host. That means installing the SR-IOV drivers and putting the following in GRUB:
GRUB_CMDLINE_LINUX_DEFAULT="quiet i915.enable_guc=3It would not need the IOMMU configuration or setting the PCI in sysfs as it's not going to be passing cards to anything else.
Finally I have not tested using vGPUs in LXC, I assume it should work but it's a lot more nuanced than just throwing numbers at it as suggested in this thread. Here is a better explanation of how to setup LXC pass-through and how to find the correct cgroup references and map them https://www.youtube.com/watch?v=0ZDr5h52OOE
I hope this helps.
I had no idea not only that you can do passthrough, but have multiple devices have access to it. Thanks a lot for sharing this
I'm not sure about Frigate, but I have a privileged Plex lxc running that shares the iGPU and handles hardware accelerated transcoding without touch grub, messing with IOMMU, etc.
/etc/pve/lxc/###.cfg
/var/lib/lxc/###/mount_hook.sh
mkdir -p ${LXC_ROOTFS_MOUNT}/dev/dri mknod -m 666 ${LXC_ROOTFS_MOUNT}/dev/dri/card0 c 226 0 mknod -m 666 ${LXC_ROOTFS_MOUNT}/dev/dri/renderD128 c 226 128 mknod -m 666 ${LXC_ROOTFS_MOUNT}/dev/fb0 c 29 0I believe I also needed to install the Intel iGPU drivers in both the host and lxc.
So I could move Frigate to an LXC (instead of Home Assistant addon), and potentially use this for both Frigate and Plex, without having to faff with passthrough?