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Doca Dpa
Use this skill when the user is doing hands-on DOCA DPA host-side work on a BlueField — creating the `doca_dpa` Core context, loading a DPACC-compiled DPA app image (`doca_dpa_app`), creating DPA threads, launching kernels via `doca_dpa_kernel_launch_update_*`, draining `doca_dpa_completion`, running `doca_dpa_cap_*` discovery, choosing between the DPA comm component (inter-DPA messaging) and the DPA verbs component (in-kernel RDMA), or debugging `DOCA_ERROR_*` from `doca_dpa_*`. Trigger even without "DOCA DPA" or "Data-Path Accelerator": "run compute on the DPA from my host", "DPA kernel hangs, no completion", "DOCA_ERROR_DRIVER on launch", "DOCA/DPACC version skew", or "does this BlueField expose a DPA". Route elsewhere for DPA-side kernel programming itself, DPACC compiler internals, host↔DPU messaging (doca-comch), host-side RDMA (doca-rdma), and GPU-initiated networking (doca-gpunetio).
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 DPA **Where to start:** This skill assumes DOCA is already installed, the user's BlueField has a DPA processor and the host can see it through DOCA, and the user is doing **hands-on DPA work from the host side** — i.e. using `doca-dpa` to load a DPA application image, launch DPA kernels, and exchange data with the DPA processor. 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 the host-side DPA API express* on this version + this BlueField generation. If the user has not installed DOCA yet, route to [`doca-setup`](../../doca-setup/SKILL.md) first; if the user is asking how to *write* the DPA-side kernel itself (the code that runs on the DPA processor, compiled by `dpacc`), that is a different scope — route via [`doca-public-knowledge-map`](../../doca-public-knowledge-map/SKILL.md) to the public DOCA DPA / DPACC / DPA-Comms / DPA-Verbs guides (this skill does not redefine those DPA-side surfaces). ## Example questions this skill answers well The CLASSES of DPA questions this skill is built to answer, each with one worked example. The agent should treat the *class* as the load-bearing piece — the worked example is a single instance. - **"How do I run a piece of compute on the DPA processor from my host program?"** — worked example: *"load a DPA kernel that counts events in a loop and reports the count back to the host"*. Answered by the two-side-program model + the host-side launch workflow in [`CAPABILITIES.md ## Capabilities and modes`](CAPABILITIES.md#capabilities-and-modes) + the bring-up steps in [`TASKS.md ## configure`](TASKS.md#configure). - **"Does this BlueField even have a DPA, and which DPA features does my DOCA install expose?"** — worked example: *"my host has a BlueField; can I use the DPA on it for a programmable control workload?"*. Answered by the dual-axis capability rule (BlueField-generation axis via `doca_dpa_cap_*` against the active `doca_devinfo` plus the DOCA-install axis via `pkg-config --modversion doca-dpa`) in [`CAPABILITIES.md ## Capabilities and modes`](CAPABILITIES.md#capabilities-and-modes) + the device-enumeration step in [`TASKS.md ## configure`](TASKS.md#configure). - **"Why does my host-side DPA setup fail with `DOCA_ERROR_NOT_SUPPORTED` even though DOCA Core looks healthy?"** — worked example: *"the BlueField generation in this host predates the DPA feature my code uses"*. Answered by the env-precondition matrix in [`CAPABILITIES.md ## Safety policy`](CAPABILITIES.md#safety-policy) + the env checklist in [`TASKS.md ## configure`](TASKS.md#configure) step 1. - **"How do I get arguments and results between my host program and my DPA kernel?"** — worked example: *"pass a buffer pointer and a length into the DPA kernel as launch arguments; read a completion back when the kernel finishes"*. Answered by the launch-argument + completion overlay in [`CAPABILITIES.md ## Capabilities and modes`](CAPABILITIES.md#capabilities-and-modes) + the launch + drain steps in [`TASKS.md ## run`](TASKS.md#run). - **"Is the DPA host-side API I'm reading about on my installed DOCA?"** — worked example: *"is the host-side launch helper I see in the docs available against the DOCA + DPACC versions on this host?"*. Answered by the version-compatibility overlay in [`CAPABILITIES.md ## Version compatibility`](CAPABILITIES.md#version-compatibility) which cross-links the canonical detection chain in [`doca-version`](../../doca-version/SKILL.md) and adds the DPA-specific *DOCA must match DPACC* overlay. - **"What does this `DOCA_ERROR_*` from a `doca_dpa_*` call mean and which layer caused it?"** — worked example: *"`DOCA_ERROR_DRIVER` on a host-side launch call — is it DOCA, the DPACC-produced image, or the DPA processor itself?"*. Answered by the DPA overlay on the cross-library taxonomy in [`CAPABILITIES.md ## Error taxonomy`](CAPABILITIES.md#error-taxonomy) + the layered ladder in [`TASKS.md ## debug`](TASKS.md#debug) that escalates to [`doca-debug`](../../doca-debug/SKILL.md). - **"How does my DPA kernel send a small message to another DPA thread on the same DPA processor?"** — worked example: *"two DPA threads in the same loaded `doca_dpa_app`; thread A sends a counter value to thread B over a DPA-side comms endpoint and thread B signals the host through `doca_dpa_completion`"*. Answered by the DPA-Comms routing rule, primitive families, host-side capability-budget rule, and DPA-Comms error overlay in [`CAPABILITIES.md ## comms`](CAPABILITIES.md#comms) plus the configure / build / modify / run / test / debug overlay in [`TASKS.md ## comms`](TASKS.md#comms). Disambiguates the DPA device-side comm component from host-side `doca-comch` and host-side `doca-rdma`. - **"How do I do RDMA directly from inside my DPA kernel to a remote peer, without round-tripping to the host?"** — worked example: *"my DPA kernel needs to fetch the next 4 KiB input buffer from a remote node via RDMA read before continuing compute; the host round-trip is the measured bottleneck"*. Answered by the 4-way RDMA matrix, the host-configures-QP / DPA-uses-QP coupling rule, the host-side cap-query rule for the specific verb, and the DPA-Verbs error overlay in [`CAPABILITIES.md ## verbs`](CAPABILITIES.md#verbs) plus the workflow overlay in [`TASKS.md ## verbs`](TASKS.md#verbs). Includes the climb-back rule for when the latency-tuning premise stops holding. ## Audience This skill serves **external developers building applications that consume the DOCA DPA library from the host side** — i.e., users whose code calls `doca_dpa_*` from host C / C++ to stand up the per-DPA-instance context, load a DPA application image that `dpacc` produced from their DPA-side source, create one or more DPA threads, launch DPA kernels with arguments, and drain completions. It is *not* for NVIDIA developers contributing to DOCA DPA itself, nor is it the place to learn how to *write* the DPA-side kernel code (that path goes through the public DOCA DPA, DPACC, DPA-Comms, and DPA-Verbs guides via [`doca-public-knowledge-map`](../../doca-public-knowledge-map/SKILL.md)). **Language scope.** DOCA DPA ships as a host-side C library with `pkg-config` module name `doca-dpa`. The host-side API is C; the DPA-side kernel is a separate translation unit written in the language the DPACC compiler accepts and compiled by `dpacc` into a binary that the host packages into the executable as the DPA application image. The shipped samples under `/opt/mellanox/doca/samples/doca_dpa/` are written in C plus DPA-side source (NVIDIA's choice). Other-language consumers are limited in practice — the DPA-side kernel has no FFI escape hatch because it must be a translation unit `dpacc` accepts — but a Rust / Go / Python host-side wrapper that drives `doca_dpa_*` setup and launches a DPA kernel image built separately is still useful, and the skill keeps the lifecycle, capability-discovery, env-precondition, and error-taxonomy guidance language-neutral. ## When to load this skill Load this skill when the user is doing hands-on DOCA DPA work **from the host side**, in any host language plus a DPA-side translation unit built by `dpacc`. Concretely: - Initializing a `doca_dpa` against a `doca_dev` that maps to a BlueField with a DPA processor visible to the host. - Loading a DPA application image (`doca_dpa_app`) that `dpacc` produced from the user's DPA-side source, into the `doca_dpa` context. - Creating one or more DPA execution contexts (`doca_dpa_thread`) so DPA kernels have somewhere to run on the DPA processor. - Launching a DPA kernel function with arguments from the host via the `doca_dpa_kernel_launch_update_*` family, and reasoning about which argument shape is supported on this install. - Attaching a `doca_dpa_completion` to observe when async DPA work finishes, and draining it from the host side. - Checking which DPA features are supported on the active `doca_devinfo` via the `doca_dpa_cap_*` family — BlueField generations differ in DPA hardware support. - Debugging a `DOCA_ERROR_*` returned from a `doca_dpa_*` call — in particular disambiguating *DPA not present on this BlueField* from *DPA feature too new for this hardware generation* from *DPACC-produced image mismatched against the host-side DOCA install* from *DPA driver layer reporting failure*. - Designing host-side bindings in a non-C language that drive a DPA application image they built separately with `dpacc` — the env-precondition and capability-discovery rules in this skill still apply. - Writing DPA-side kernel code that calls the DPA device-side comm component **`libdoca_dpa_dev_comm.a`** (header `doca_dpa_dev_comch_msgq.h`) — for inter-DPA-thread messaging or coordination signals between DPA threads on the same `doca_dpa_app`. The DPA-Comms routing rule, primitive families, capability rule (there is no per-primitive host cap-query family — host-side DPA discovery is only `doca_dpa_cap_is_supported` / `doca_dpa_cap_get_max_kernel_time_alive_supported`), error overlay (`_AGAIN` → kernel must yield; `_BAD_STATE` disambiguation from the parent's host-side `_BAD_STATE`), and the configure / build / modify / run / test / debug overlay live in [`CAPABILITIES.md ## comms`](CAPABILITIES.md#comms) and [`TASKS.md ## comms`](TASKS.md#comms) under this same skill. - Writing DPA-side kernel code that calls the DPA device-side verbs component **`libdoca_dpa_dev_verbs.a`** (header `doca_dpa_dev_verbs.h`) — for RDMA from inside the DPA kernel to a remote peer when the host round-trip is the measured latency bottleneck. The 4-way RDMA matrix, the host-configures-QP / DPA-uses-QP coupling rule, the capability rule (no per-verb host cap-query family exists; verb availability follows the BlueField generation + matched DOCA/DPACC install, read from `doca_dpa_dev_verbs.h` and the shipped sample), the IO_FAILED → CQE-inspection overlay, and the climb-back rule live in [`CAPABILITIES.md ## verbs`](CAPABILITIES.md#verbs) and [`TASKS.md ## verbs`](TASKS.md#verbs) under this same skill. Do **not** load this skill for general DOCA orientation, install of DOCA or the DPACC compiler, the DPA-side programming model itself (how to write a DPA kernel; the DPA device-side comm and verbs components (`libdoca_dpa_dev_comm.a` / `libdoca_dpa_dev_verbs.a`) that run *inside* the DPA kernel), or non-DPA library questions. For those, route through [`doca-public-knowledge-map`](../../doca-public-knowledge-map/SKILL.md) to the matching upstream guide. ## What this skill provides This is a **thin loader**. The body keeps only the orientation needed to pick the right next file. The substantive DPA-specific material lives in two companion files: - `CAPABILITIES.md` — what the host-side DPA API can express on this version + this BlueField generation: the per-DPA-instance `doca_dpa` context, the loaded `doca_dpa_app` image produced by `dpacc`, the `doca_dpa_thread` execution context, the host-initiated kernel launch surface (`doca_dpa_kernel_launch_update_*`), the `doca_dpa_completion` mechanism, the capability-query surface (`doca_dpa_cap_*`), the DPA error taxonomy mapped onto the cross-library `DOCA_ERROR_*` set, the observability surface (host-side completions plus the public DPA developer tools surface reachable via `doca-public-knowledge-map`), and the safety policy that gates env preconditions (DPA-capable BlueField, matched DOCA + DPACC versions, DPA-side image and host-side expected entry points agree). - `TASKS.md` — step-by-step workflows for the six in-scope DPA 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 where DOCA is already installed at the standard location, a BlueField with a DPA processor is physically present and visible to the host, the DPACC compiler is installed at a version matched to the DOCA install per the DOCA Compatibility Policy, and the user already knows how (at least at a sketch level) to write the DPA-side kernel that `dpacc` will compile. It does not cover installing DOCA or the DPACC compiler — that path goes through [`doca-setup`](../../doca-setup/SKILL.md). ## What this skill deliberately does not ship This skill is **agent guidance**, not a samples or templates bundle. To keep the boundary clean, it deliberately does not contain — and pull requests should not add: - **Pre-written DOCA DPA application source code or DPA-side kernel source, in any language.** The verified DPA source is the shipped C + DPA-side samples at `/opt/mellanox/doca/samples/doca_dpa/`. The agent's job is to route the user to those files and prescribe a minimum-diff modification on them via the universal modify-a-sample workflow in [`doca-programming-guide`](../../doca-programming-guide/SKILL.md), layered with the DPA-specific overrides in [`TASKS.md ## modify`](TASKS.md#modify). - **Standalone build manifests** (`meson.build`, `CMakeLists.txt`, …) parked inside the skill. The agent constructs the build manifest *in the user's project directory* against the user's installed DOCA + DPACC compiler, where `pkg-config --modversion doca-dpa` and the installed `dpacc` are the two sources of truth. - **A `samples/`, `bindings/`, or `reference/` subtree** of any kind. A mock or incomplete artifact in this skill's tree, even one labeled "reference", is misleading: users will read it as buildable. - **DPA device-side content for the comm / verbs components (`libdoca_dpa_dev_comm.a` / `libdoca_dpa_dev_verbs.a`).** These are *DPA-side* archives shipped as part of `doca-dpa` (NOT separate pkg-config modules): their symbols are called from inside the DPA kernel and linked into the DPA image by `dpacc`, not from the host. Their public guides are reachable via [`doca-public-knowledge-map`](../../doca-public-knowledge-map/SKILL.md). This skill names them and routes; it does not redefine them. ## Loading order 1. Read this `SKILL.md` first to confirm the user's question is in scope (host-side DPA work, not DPA-side kernel-writing). 2. **For the DPA capability matrix, the `doca_dpa` per-instance context, the loaded `doca_dpa_app` image, the `doca_dpa_thread` execution context, the kernel-launch + completion model, the dual capability query, the env-precondition policy, 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 DPA overlay that DOCA must match the DPACC compiler), and [`doca-public-knowledge-map`](../../doca-public-knowledge-map/SKILL.md) whenever the right answer is "look it up in the public DOCA DPA, DPACC, DPA-Comms, or DPA-Verbs guide, or in the on-disk install layout" rather than "DPA host-side-specific guidance". ## Related skills - [`doca-public-knowledge-map`](../../doca-public-knowledge-map/SKILL.md) — the routing table for every public DOCA documentation source and the on-disk layout of an installed DOCA package. The DPA public guide is at <https://docs.nvidia.com/doca/sdk/DOCA-DPA/index.html>; the DPACC compiler guide, the DPA-Comms guide (DPA-side communications), the DPA-Verbs guide (DPA-side verbs), and the DPA Tools umbrella (developer / admin CLIs for DPA) live in the same routing table and are *companion surfaces* to this skill rather than redefined by it. - [`doca-setup`](../../doca-setup/SKILL.md) — env preparation, install verification, DPACC compiler install / verification, and the *I have no install yet* path with the public NGC DOCA container. This skill assumes its preconditions are satisfied AND that DPACC is installed at a version that matches DOCA. - [`doca-version`](../../doca-version/SKILL.md) — canonical DOCA version-handling rules. This skill's `## Version compatibility` cross-links the four-way match rule and adds the DPA-specific *DOCA-and-DPACC must match* overlay per the DOCA Compatibility Policy. - [`doca-structured-tools-contract`](../../doca-structured-tools-contract/SKILL.md) — the bundle's structured-tools precedence rule (detect / prefer / fall back / report). The Command appendix in [TASKS.md](TASKS.md) honors this contract. - [`doca-programming-guide`](../../doca-programming-guide/SKILL.md) — general DOCA programming patterns shared by every library: the canonical `pkg-config` + meson build pattern, the universal modify-a-shipped-sample first-app workflow, the universal Core-context lifecycle, the cross-library `DOCA_ERROR_*` taxonomy, and the program-side debug order. This skill layers DPA specifics on top. - [`doca-debug`](../../doca-debug/SKILL.md) — the cross-cutting debug ladder (install / version / build / link / runtime / program / driver). DPA-specific debug (DPACC + DOCA version skew, DPA not present on this BlueField generation, DPA kernel hangs that show no host-side completion, launch-argument shape mismatches between the host launch call and the DPA-side function signature) overlays on top of that ladder. DOCA DPA's DPA device-side components — the comm archive `libdoca_dpa_dev_comm.a` (communication primitives the DPA kernel itself calls, header `doca_dpa_dev_comch_msgq.h`) and the verbs archive `libdoca_dpa_dev_verbs.a` (ibverbs-like RDMA verbs the DPA kernel itself calls, header `doca_dpa_dev_verbs.h`) — are **DPA-side archives shipped within `doca-dpa`**, not separate pkg-config modules, and each has its own public guide. No library skill ships for them in this bundle yet; for any DPA-side question, route via [`doca-public-knowledge-map`](../../doca-public-knowledge-map/SKILL.md) to the public *DOCA DPA Comms* and *DOCA DPA Verbs* guides and to the shipped `/opt/mellanox/doca/samples/doca_dpa/` samples (which include both host-side and DPA-side translation units). Conflating them with `doca-dpa` is the single most common DPA first-app design error.