Windows Vm Patterns

Windows VM Patterns

iGPU PCI Passthrough

1. Bind iGPU to vfio-pci via runtime sysfs manipulation (echo to /sys/bus/pci/drivers/). Do NOT write modprobe config files (blacklist-igpu.conf, vfio-pci-igpu.conf). Sysfs-only binding is reversible without initramfs updates.

2. NEVER bind the sole GPU on an AMD host to vfio-pci. The amdgpu driver removal triggers a kernel panic when it is the only framebuffer. Hard-fail if lspci | grep -c 'VGA compatible controller' < 2 and vendor is AMD. Intel single-GPU hosts survive (SSH stays up).

3. Cleanup MUST modprobe -r the GPU driver BEFORE modprobe to re-probe devices. Simply running modprobe i915 after vfio-pci unbind is a no-op if the module is already loaded. Sequence: unbind → modprobe -r → PCI rescan → modprobe → wait for DRI.

4. Previous bug: cleanup removed /etc/modprobe.d/blacklist-igpu.conf — a file the role never created. Cleanup MUST only remove artifacts the deploy creates.

Per-Host VMID Computation

5. When multiple hosts share a Proxmox node (common in test environments), compute VMID as base + groups['flavor_group'].index(inventory_hostname). Apply the same computation in provision, verify, AND cleanup.

6. The default cleanup list must include the full range of possible per-host VMIDs (base, base+1, base+2, ...) to cover all group sizes.

Image Upload: Use /var/tmp, Not /tmp

7. Proxmox /tmp is often tmpfs (~7.8 GB). Windows qcow2 images are 8-18 GB. ALWAYS use /var/tmp/ (real disk) for image uploads and qemu-img convert output.

8. Previous bug: qemu-img convert to /tmp/ failed with "No space left on device" on a host with 8 GB tmpfs.

QEMU Guest Agent Communication

9. Use qm guest cmd <vmid> ping to detect GA readiness. Use qm guest exec <vmid> --timeout N -- cmd /c "..." for in-VM commands. These bypass the network entirely — no SSH, no sshpass, no ProxyJump needed.

10. IP discovery: qm guest cmd <vmid> network-get-interfaces returns JSON. Parse with Python, skip Loopback interfaces AND 169.254.x.x (APIPA/link-local) addresses, extract first routable IPv4 address. Retry until a DHCP lease is obtained.

11. Previous bug: Guest Agent responded to ping before Windows DHCP client obtained a lease. The first IP returned was 169.254.143.117 (APIPA). SSH to this link-local address timed out. Fix: filter 169.254. prefix in the Python parser and increase retries.

12. qm guest cmd ping is a simple command — use ansible.builtin.command, not ansible.builtin.shell. Only use shell when there's an actual pipeline.

Windows Unattended Installation

13. Disable Windows Defender and Windows Update in the specialize pass via RunSynchronous + reg add to Group Policy keys. Do NOT use FirstLogonCommands — Tamper Protection blocks Defender changes from user-context commands.

14. Re-enable Defender and set Windows Update to Manual at the end of post-install.ps1. This prevents AV interference during setup but leaves the system in a safe state.

15. Post-install completion: write a marker file (C:\post-install-done.txt) at the end of post-install.ps1. Poll with qm guest exec checking for the marker. Hard-fail if marker not found within timeout — proceeding with an incomplete image violates the one-path principle.

PowerShell via Ansible

16. NEVER wrap ansible.builtin.raw commands in powershell -Command "..." when the SSH shell is already PowerShell. The outer shell expands $variables in double-quoted strings before passing to the inner PowerShell instance.

17. Previous bug: $svc = Get-Service ... in powershell -Command "... $svc ..." — the outer PowerShell expanded $svc to empty, causing syntax errors.

EFI Disk Format

18. On LVM-thin storage, EFI disks MUST use format=raw. The qcow2 format is unsupported for EFI disks on LVM-thin and causes "unsupported format" errors.

LAN Host VM Connectivity

19. VMs on LAN hosts get LAN IPs (e.g., 10.10.10.x) not directly routable from the controller. Add conditional ProxyJump via PRIMARY_HOST when the host is in lan_hosts.