LSIOMMU(1)

💅 LSIOMMU(1) 💅

okay so this is a User Commands page for lsiommu, and bestie, it's literally a little detective tool for your hardware. let's get into it 🫶

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✨ NAME ✨

lsiommu — it enumerates IOMMU groups, and lists the PCIe devices and USB controllers associated with each group 🌸

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🦋 DESCRIPTION 🦋

okay so lsiommu is a hardware inspection utility that shows you the relationships between IOMMU groups, physical PCIe hardware, and nested USB buses. it's giving "family tree but for your motherboard" ngl 😭

it's commonly used when you're setting up Kernel-based Virtual Machines (KVM) with VFIO hardware passthrough — like, PCIe passthrough of a host device (such as a graphics card or a network interface) to a guest VM. that's the main character use case fr fr 👑

so the utility performs four core actions:

🌈 Group Mapping

it iterates sequentially through the system kernel directory /sys/kernel/iommu_groups/ to discover physical hardware isolation clusters. cute little walk through the kernel tree, no cap ✨

🔥 Hardware Details

it executes lspci(8) queries to extract and cleanly format vendor names, hardware descriptions, and precise hardware IDs for graphics cards, network interfaces, and storage drives. it ate, honestly 💅

💀 Reset Support Flag

it checks the system tree for device reset capabilities. it appends an [R] flag if a hardware device natively supports a function-level reset — which is required for reliable virtual machine attach/detach cycles. so like, if you're hot-swapping devices between VMs, this flag is your bestie, pay attention 🙈

🧚 USB Mapping

it correlates nested USB controllers via lsusb(8) with their parent PCIe buses. this exposes exactly which physical USB ports belong to which isolated IOMMU group — so you know precisely which ports go with which group, periodt 💜

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⭐ NOTES ⭐

IOMMU groups are a part of the kernel's VFIO (Virtual Function IO) driver framework — here's the link, bookmark it, iykyk:

https://docs.kernel.org/driver-api/vfio.html

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🎀 SEE ALSO 🎀

lspci(8), lsusb(8),

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and that's the whole vibe 💖 this one comes from the Linux System Utilities crew, dated July 2026 — go check your IOMMU groups bestie, they're waiting 🌸🦋🍓