Skills DirectorySearch all skills ↗AI agent skill · by @NVIDIA
Doca Devemu
Use this skill when the user is doing hands-on DOCA Device Emulation on a BlueField DPU — exposing a custom emulated PCIe device the host sees as a real peripheral while DPU-side code runs the backend, picking the sub-library (PCI Generic, virtio-net, virtio-fs), wiring the per-sub-library Core context plus doorbell / DMA primitives, querying `doca_devemu_*_cap_*`, or debugging DOCA_ERROR_* from a `doca_devemu_*` call. Trigger even when the user does not say "devemu" — typical implicit phrasings include "expose a custom PCIe device from BlueField to the host", "host should see a virtio NIC backed by my DPU code", "lspci does not show my emulated device", "device enumerated but no driver binds", "DPU sees nothing when host kicks the queue", or "virtio feature negotiation failed at bind". Refuse and route elsewhere for the packaged DOCA SNAP / Virtio-net Services, host-side virtio kernel drivers, backend body design, or standard BlueField NIC behavior — those belong to other skills.
Archived 2026-10-23 · Source updated 2026-09-30 · License: Apache-2.0. Check the original repository for the latest version.
SKILL.md instructions
# DOCA Device Emulation **Where to start:** This skill assumes DOCA is already installed on the host AND on the BlueField, the user is doing **hands-on emulated-PCIe-device work** from the DPU side (writing the backend that the host's kernel driver will talk to over the emulated PCIe surface), and the user knows which CLASS of emulated device they want to build. Open [`TASKS.md`](TASKS.md) if the user wants to *do* something (configure / build / modify / run / test / debug); open [`CAPABILITIES.md`](CAPABILITIES.md) when the question is *what can Device Emulation express* on this DOCA version + this BlueField generation + this firmware. If the user has not installed DOCA yet, route to [`doca-setup`](../../doca-setup/SKILL.md) first. **Before anything else, the agent must route the user to the right sub-library** — DOCA Device Emulation is an *umbrella* that covers PCI Generic (raw PCIe device emulation), virtio-net (emulated virtio network device), and virtio-fs (emulated virtio filesystem device); each sub-library has its own context, its own `pkg-config` module, and its own capability surface. The sub-library selection rule lives in [`CAPABILITIES.md ## Capabilities and modes`](CAPABILITIES.md#capabilities-and-modes). If the user wants a packaged solution rather than a library (e.g. *"I want NVMe SNAP on my host without writing the backend myself"*, or *"I want a managed virtio-net daemon"*), route via [`doca-public-knowledge-map`](../../doca-public-knowledge-map/SKILL.md) to the DOCA SNAP Service / DOCA Virtio-net Service guides — those services are *built on top of* this library and are a different artifact than what this skill covers. ## Audience This skill serves **external developers building applications that consume the DOCA Device Emulation library** — i.e., users whose DPU-side code calls `doca_devemu_pci_*`, `doca_devemu_virtio_*`, or `doca_devemu_vfs_*` (directly in C / C++, or through FFI / bindings from another language) to expose an emulated PCIe device to the host that the host's existing kernel drivers can drive as if it were a real PCIe peripheral. It is *not* for NVIDIA developers contributing to DOCA Device Emulation itself, and it is *not* the right artifact for users who want a packaged emulated-device daemon they do not have to write the backend for (the DOCA SNAP Service and the DOCA Virtio-net Service are the packaged options that build on top of this library). **Language scope.** DOCA Device Emulation ships as a C library; this skill covers three sub-libraries end-to-end. Select the exact installed `pkg-config` module for the user's emulation class (see the sub-library selection table in [`CAPABILITIES.md ## Capabilities and modes`](CAPABILITIES.md#capabilities-and-modes)). The shipped samples under `/opt/mellanox/doca/samples/doca_devemu/` are written in C. C and C++ consumers are the canonical case and the worked examples in `TASKS.md` assume that path. Other-language consumers (Rust, Go, Python, …) consume the same `*.so` files through FFI or language-specific bindings; the skill's contribution in that case is to keep the sub-library selection, umbrella lifecycle, capability-discovery, permission, and error-taxonomy guidance language-neutral, and to route the agent to the public C ABI as the authoritative surface that any wrapper will eventually call. ## When to load this skill Load this skill when the user is doing hands-on DOCA Device Emulation work from the DPU side, in any language. Concretely: - Deciding which Device Emulation sub-library (PCI Generic, virtio-net, virtio-fs) the user needs — the umbrella selection question is *this skill's load-bearing first move*. - Initializing the per-sub-library DOCA Core context on the DPU (one context per emulated device per sub-library) and configuring the doorbell / DMA primitives the host's PCIe driver will interact with. - Reading per-sub-library capability surface via the `doca_devemu_pci_cap_*`, `doca_devemu_virtio_cap_*`, or `doca_devemu_vfs_cap_*` query families against the active `doca_devinfo` BEFORE assuming a particular feature bit or device characteristic is available. - Choosing between writing the backend with `doca-devemu` yourself and adopting a packaged service (DOCA SNAP Service / DOCA Virtio-net Service) that already wraps this library. - Debugging a `DOCA_ERROR_*` returned from a `doca_devemu_*` call — in particular disambiguating *firmware-level emulation type not enabled* from *BlueField generation does not support this sub-library at all* from *DPU-side process lacks privilege* from *host-side kernel driver did not bind*. - Designing or extending non-C bindings (Rust, Go, Python, …) that wrap one of the device-emulation sub-libraries — for the sub-library selection, umbrella lifecycle, capability- discovery, permission, and error-taxonomy rules the wrapper must honor. Do **not** load this skill for general DOCA orientation, install of DOCA itself, the host-side kernel driver for the emulated device class (virtio-net / virtio-blk / virtio-fs kernel drivers ship with the host kernel and are not part of DOCA), the packaged SNAP / Virtio-net services (they are separate artifacts with their own service guides), or for standard NIC behavior on the BlueField data path (use [`doca-flow`](../doca-flow/SKILL.md) + [`doca-eth`](../doca-eth/SKILL.md) instead — Device Emulation is for *custom* emulated devices, not for shaping the BlueField's built-in NIC personality). ## What this skill provides This is a **thin loader**. The body keeps only the orientation needed to pick the right next file. The substantive Device Emulation-specific material lives in two companion files: - `CAPABILITIES.md` — what Device Emulation can express on this version + this BlueField generation + this firmware: the umbrella architecture (host sees an emulated PCIe device; DPU runs the backend), the sub-library selection rule (PCI Generic vs virtio-net vs virtio-fs), the per- sub-library Core context shape, the doorbell / DMA primitives that bridge host ↔ DPU, the per-sub-library capability-query family (`doca_devemu_*_cap_*`), the per-sub-library `pkg-config` module name, the Device Emulation error taxonomy mapped onto the cross-library `DOCA_ERROR_*` set, the observability surface, the library-vs-packaged-service path-selection rule, and the safety policy that gates env preconditions (DPU-side privileges, BlueField firmware-level emulation type enablement, BlueField generation actually supporting the emulation class). - `TASKS.md` — step-by-step workflows for the six in-scope Device Emulation verbs: `configure`, `build`, `modify`, `run`, `test`, `debug`. Plus a `Deferred task verbs` block that points out-of-scope questions at the right next skill. The skill assumes a host + BlueField pair where DOCA is already installed at the standard location on both sides, the BlueField firmware has the emulation type the user wants to build enabled, the user has the privileges their public install profile expects (in particular, sudo on the DPU side to perform PCIe-level emulation), and the host kernel ships the standard driver for the emulated device class the user is building. It does not cover installing DOCA, flipping firmware-level configuration, or installing host-side kernel drivers — those paths go through [`doca-setup`](../../doca-setup/SKILL.md). ## Loading order 1. Read this `SKILL.md` first to confirm the user's question is in scope (custom emulated PCIe device built on the `doca-devemu` library, not the packaged SNAP / Virtio-net services, not the host-side kernel driver, not standard NIC behavior). 2. **For the umbrella architecture, the sub-library selection rule (PCI Generic vs virtio-net vs virtio-fs), the per- sub-library Core context shape, the doorbell / DMA primitives, the per-sub-library capability-query rule, the per-sub-library `pkg-config` modules, the library-vs- packaged-service path-selection rule, the error taxonomy, the observability surface, and the safety policy, see [CAPABILITIES.md](CAPABILITIES.md).** 3. **For step-by-step workflows — configure, build, modify, run, test, debug — see [TASKS.md](TASKS.md).** Both companion files cross-link to each other, [`doca-version`](../../doca-version/SKILL.md) for the canonical DOCA version-handling rules (with the Device Emulation overlay that the chosen sub-library's `pkg-config` module plus the firmware-level emulation slot plus the `doca_devemu_*_cap_*` query are all part of *"is this emulation supported here"*), and [`doca-public-knowledge-map`](../../doca-public-knowledge-map/SKILL.md) whenever the right answer is "look it up in the public DOCA Device Emulation umbrella guide, the per-sub-library guide linked from it, the DOCA SNAP / Virtio-net Service guide, or in the on-disk install layout" rather than "Device Emulation- specific guidance". ## Example questions this skill answers well See [`references/details.md`](references/details.md#example-questions-this-skill-answers-well). ## What this skill deliberately does not ship See [`references/details.md`](references/details.md#what-this-skill-deliberately-does-not-ship). ## Related skills See [`references/details.md`](references/details.md#related-skills).