Ubuntu VM102 virtio blob/host-visible trial (2026-11-06)

Read-only preflight:
- Guest virtio-gpu reported: +virgl +edid -resource_blob -host_visible.
- Guest kernel: 7.0.0-38-generic.
- Mesa: 25.2.8-0ubuntu0.24.04.1.
- Current PVE display before trial: vga=virtio-gl.

Trial:
- Gracefully stopped VM102.
- Temporarily replaced managed display with:
  vga=none
  args=-device virtio-vga-gl,id=vga,blob=true,hostmem=512M
- VM process initially reported running, but the guest agent never became available after 70 seconds.
- No production stream was left on the trial configuration.

Rollback:
- Restored vga=virtio-gl.
- Removed custom args.
- Started VM102.
- Guest agent returned after 2 seconds.
- Final guest feature flags remain +virgl +edid -resource_blob -host_visible.
- Sunshine process is running with capture=kms and encoder=software.

Conclusion:
- The current Proxmox/QEMU managed virtio display path cannot be enabled for blob/host-visible resources through this custom override without losing stable guest boot/agent availability.
- Trial was fully reverted. Windows VM100 and Kylin VM101 were not changed.
- A production zero-copy path now requires a Proxmox/qemu-server version that exposes the virtio-vga-gl blob/hostmem properties natively, or a separate GPU/real hardware encoder for VM102.
