libevm/proxmox_vm_gpu_steps.md

## proxmox_vm_gpu_steps.md

      
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              proxmox_vm_gpu_steps.md
            
          
    Proxmox VE + RTX 5090 Passthrough (Debian 13)

This document summarizes the end‑to‑end, known‑good process to:

Enable GPU passthrough on Proxmox VE
Create a Debian 13 (trixie) VM
Attach an RTX 5090 via PCI passthrough
Run the VM headless (Display: none)
Access the VM via serial console and SSH

The steps are ordered and opinionated to avoid the common traps.

1. Proxmox Host: Enable GPU Passthrough

1.1 Enable IOMMU

Edit /etc/default/grub on the Proxmox host:
GRUB_CMDLINE_LINUX_DEFAULT="quiet intel_iommu=on iommu=pt"

(Use amd_iommu=on iommu=pt on AMD CPUs.)
Apply and reboot:
update-grub
reboot
Verify:
dmesg | grep -e IOMMU -e DMAR

1.2 Bind RTX 5090 to VFIO (host must NOT use NVIDIA)

Confirm device IDs:
lspci -nn | grep -i nvidia
Example (yours):

GPU: 10de:2b85
Audio: 10de:22e8

Create VFIO binding:
echo "options vfio-pci ids=10de:2b85,10de:22e8 disable_vga=1" > /etc/modprobe.d/vfio.conf
Blacklist nouveau:
echo -e "blacklist nouveau\noptions nouveau modeset=0" > /etc/modprobe.d/blacklist-nouveau.conf
Ensure VFIO modules load:
printf "vfio\nvfio_pci\nvfio_iommu_type1\n" > /etc/modules-load.d/vfio.conf
Rebuild initramfs and reboot:
update-initramfs -u -k all
reboot
Verify after reboot:
lspci -nnk | grep -A3 -i nvidia
Expected:
Kernel driver in use: vfio-pci


2. Create the Debian 13 VM (Proxmox Web UI)

2.1 VM Creation (Wizard)

General

Any VM ID / Name

OS

Debian 13 (trixie) ISO
Guest OS: Linux

System (CRITICAL)

BIOS: OVMF (UEFI)
Add EFI Disk: ✔ (Pre‑enroll keys ❌)
Machine: q35
SCSI Controller: VirtIO SCSI single
QEMU Agent: ✔

Disks / CPU / Memory / Network

Defaults are fine
Network model: VirtIO

Create the VM but do not rely on GPU yet.

3. Install Debian (Temporary Display)

During installation, you need some console.
Recommended:

Display: Standard VGA (or SPICE)

Install Debian normally.
Inside Debian, install essentials:
apt install openssh-server qemu-guest-agent
Enable guest agent:
systemctl enable --now qemu-guest-agent
Confirm you can SSH into the VM.

4. Switch VM to Headless + Serial Console

4.1 Disable Virtual Display


VM → Hardware → Display → None

(noVNC will no longer work — this is expected)

4.2 Add Serial Console (Web UI)


VM → Hardware → Add → Serial Port

Port: serial0


VM → Options → Console → set to Serial0


Inside Debian (one‑time):
systemctl enable serial-getty@ttyS0.service
systemctl start serial-getty@ttyS0.service
Now the Proxmox Console button works even with Display: none.

5. Attach RTX 5090 to the VM

5.1 Add PCI Devices (Web UI)

Add GPU:

Hardware → Add → PCI Device
Device: 0000:e1:00.0
✔ PCI‑Express
❌ Primary GPU
❌ ROM‑Bar

Add audio:

Device: 0000:e1:00.1
✔ PCI‑Express

Do NOT enable “Primary GPU” (this avoids x-vga crashes).

5.2 Start the VM

Inside Debian:
lspci | grep -i nvidia
You should now see:
NVIDIA Corporation GB202 [GeForce RTX 5090]


6. Install NVIDIA Driver Inside Debian VM

Enable non‑free repositories:
deb http://deb.debian.org/debian trixie main contrib non-free non-free-firmware
deb http://deb.debian.org/debian-security trixie-security main contrib non-free non-free-firmware
deb http://deb.debian.org/debian trixie-updates main contrib non-free non-free-firmware

Install headers + driver:
apt update
apt install linux-headers-$(uname -r)
apt install nvidia-driver firmware-misc-nonfree
Reboot the VM.
Verify:
nvidia-smi

7. Final Access Model (Expected)


❌ noVNC / VGA
✅ Serial console (Proxmox Web UI)
✅ SSH (ssh user@vm_ip)
✅ Full RTX 5090 acceleration inside Debian


Key Rules (TL;DR)


Never install NVIDIA drivers on the Proxmox host
q35 + OVMF is mandatory
Do NOT use Primary GPU / x‑vga
Display: none + Serial Port is the correct headless setup
RTX 5090 works cleanly with Debian 13 + modern Proxmox


This configuration is stable, repeatable, and avoids all known RTX 50‑series passthrough pitfalls.
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