Lab notes
Problems I hit building one specific home lab, and what fixed them. Tier 3 territory — the guides don't assume any of this.
The rest of this site is written for any budget. This section is different: it’s the engineering log of one particular build — a used enterprise server, a couple of GPUs, Proxmox, and a lot of evenings — kept because every one of these problems cost me hours that a search engine couldn’t save, and someone else is hitting the same wall right now.
Each note follows the same shape: symptom → cause → fix → how to make it stick. Commands are real and were run; versions are stated because they matter. Scripts referenced here live in the lab/ folder of the site’s repo.
If one of these saved you time, or you found a better way, open an issue.
- Intel Arc in a Proxmox VM: no Resizable BAR, no oneAPI
An Arc Pro B-series card passed through to a VM on a server whose BIOS has no ReBAR option. Vulkan worked; Level Zero, oneAPI and torch.xpu refused to initialize. The fix is a sysfs write on the host — and a hookscript to make it survive reboots.
- PyTorch on Intel Arc (torch.xpu) inside a VM, and ComfyUI on top
Once the BAR problem is solved, getting a working torch.xpu environment on Battlemage in an Ubuntu VM — and running ComfyUI as a service on it — is mostly a matter of picking versions that agree with each other.