[BUG] UEFI VM boot hangs at TianoCore / boot order corrupted when cloning in XO6

[gounthar]

Proxy filing — Originally reported by escape222 on the XCP-ng forum, with a related observation from MajorP93.

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Are you using XOA or XO from the sources?

XOA / XO6

Which release channel?

Not specified

Describe the bug

When cloning a VM from a template in XO6, the UEFI boot order is corrupted: Network Boot is inserted as the first boot option. The VM then hangs at the TianoCore boot screen for 2+ minutes waiting for PXE to time out before falling through to the hard drive. The same clone operation in XO5 does not alter the boot order.

A second reporter (MajorP93) observes greatly increased UEFI VM boot times across the board, with the kernel log showing "installing Xen timer" and "spinlock event" messages for each CPU during boot — behavior not present for BIOS-mode VMs and potentially related to the same UEFI configuration issue.

Error message

# escape222 — boot order corruption after XO6 clone:
# VM hangs 2+ minutes at TianoCore screen (Network Boot inserted as first option)
# No error text — visible only as a stall at firmware screen

# MajorP93 — Xen timer / spinlock events during UEFI VM boot:
Apr 27 11:35:06 xo01 kernel: Xen: using vcpuop timer interface
Apr 27 11:35:06 xo01 kernel: installing Xen timer for CPU 0
Apr 27 11:35:06 xo01 kernel: smpboot: CPU0: AMD EPYC 7702P 64-Core Processor
Apr 27 11:35:06 xo01 kernel: cpu 0 spinlock event irq 52
Apr 27 11:35:06 xo01 kernel: installing Xen timer for CPU 1
Apr 27 11:35:06 xo01 kernel: cpu 1 spinlock event irq 81
Apr 27 11:35:06 xo01 kernel: installing Xen timer for CPU 2
Apr 27 11:35:06 xo01 kernel: cpu 2 spinlock event irq 82
[... CPUs 3–7 same pattern ...]

To reproduce

Boot order corruption (escape222):

1. Have a UEFI-enabled Debian 13 VM on XO6
2. Clone it from a template using XO6
3. Boot the clone

Observed: clone hangs at TianoCore for ~2 minutes (PXE timeout), then boots from disk.
Expected: clone boots directly from disk without delay.

Note: the same operation via XO5 does not change the boot order.

Slow UEFI boot (MajorP93):

1. Create any UEFI VM on XCP-ng
2. Boot it and observe kernel log

Observed: "installing Xen timer for CPU N" and "cpu N spinlock event irq XX" for all CPUs; boot time greatly increased vs. BIOS-mode VMs.

Expected behavior

Cloning a UEFI VM via XO6 preserves the original boot order. UEFI VM boot time is comparable to BIOS VM boot time.

Environment

• Hypervisor: XCP-ng (version not specified)
• XOA version: XO6 (exact version not specified); issue absent in XO5
• CPU: AMD EPYC 7702P (MajorP93's environment)

Additional context

Reported by community members on the XCP-ng forum.

Forum discussion: https://xcp-ng.org/forum/topic/11604
Direct posts: https://xcp-ng.org/forum/post/104741, https://xcp-ng.org/forum/post/104771