GPU PCI Address Instability: When Your Card Moves Between Reboots

I spent an entire afternoon debugging a VM that refused to boot, only to find out my GPU had decided to change its PCI address. One reboot and the device that lived at 01:00.0 suddenly migrated to 02:00.0 . Because my Proxmox VM configuration was pinned to the old address, the VM crashed with a QEMU assertion error, and the GPU simply vanished from the guest. This usually happens because of how the BIOS handles PCIe enumeration during POST. If you have multiple PCIe devices or a complex motherbo