{
  "observed_at": "2026-09-08T06:42:47.272198+00:00",
  "read_only": true,
  "selected_kernel_iommu_arguments": [],
  "gpu_iommu_domains": [
    {
      "gpu_index": 0,
      "iommu_group_present": true,
      "iommu_domain_type": "DMA-FQ"
    },
    {
      "gpu_index": 1,
      "iommu_group_present": true,
      "iommu_domain_type": "DMA-FQ"
    }
  ],
  "limitation": "No ACS or data-transfer test; no boot/firmware change",
  "interpretation": "DMA-FQ is translated DMA with batched invalidation. Both GPU paths currently use translation. NVIDIA documents a bare-metal PCIe P2P incompatibility for translated IOMMU; this is a prerequisite to review, not a proven cause of the prior hang.",
  "sources": [
    "https://raw.githubusercontent.com/torvalds/linux/v7.0/Documentation/ABI/testing/sysfs-kernel-iommu_groups",
    "https://docs.nvidia.com/deeplearning/nccl/user-guide/docs/troubleshooting/gpu_troubleshooting.html"
  ]
}