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From: Yao Xu <xy2462381442@gmail.com>
To: pve-devel@lists.proxmox.com
Cc: Yao Xu <Xy2462381442@gmail.com>
Subject: [PATCH pve-docs 0/2] qm: pci passthrough: the AtomicOps caveat of the all-functions form
Date: Mon, 24 Aug 2026 19:08:26 +0200	[thread overview]
Message-ID: <20260824170828.42821-1-Xy2462381442@gmail.com> (raw)

Passing a card with the shortened ``00:02`' syntax quietly costs the
guest PCIe AtomicOps. QEMU adds AtomicOp completer support to the
emulated root port only for a single-function device, so the port ends
up advertising none, and nothing in the config or the logs points at
the cause. The failure surfaces as a driver or ROCm problem several
layers away.

Patch 1 documents this next to the paragraph that introduces the
syntax. Patch 2 appends the function to the GPU example below it, which
currently pairs pcie=on with the all-functions form and would hit the
caveat as written.

Verified on Proxmox VE 9.2.4 with QEMU 11.0.2 and two RX 7900 XT
(gfx1100) in one q35 guest; the reproduction is in patch 1.

Yao Xu (2):
  qm: pci passthrough: note the AtomicOps caveat of all-functions form
  qm: pci passthrough: name the function in the GPU example

 qm-pci-passthrough.adoc | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

-- 
2.50.1 (Apple Git-155)




             reply	other threads:[~2026-08-25  8:11 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-08-24 17:08 Yao Xu [this message]
2026-08-24 17:08 ` [PATCH pve-docs 1/2] qm: pci passthrough: note the AtomicOps caveat of all-functions form Yao Xu
2026-08-24 17:08 ` [PATCH pve-docs 2/2] qm: pci passthrough: name the function in the GPU example Yao Xu
2026-08-25 13:16 ` [PATCH pve-docs 0/2] qm: pci passthrough: the AtomicOps caveat of the all-functions form Dominik Csapak
     [not found]   ` <CANzZxgda3RsuakrK2wmDH3ez-hbby3qNte+qkfixipSrWoBzaQ@mail.gmail.com>
2026-08-25 14:09     ` Dominik Csapak

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