Doca Eth

DOCA Ethernet

Where to start: This skill assumes DOCA is already installed and the user is doing hands-on packet-queue work on a host or BlueField with DOCA. Open TASKS.md if the user wants to do something (configure / build / modify / run / test / debug); open CAPABILITIES.md when the question is what can a DOCA Ethernet queue express on this version. If the user has not installed DOCA yet, route to doca-setup first. If the user is asking "how do I get packets to land on my RX queue at all", the answer lives in doca-flow — DOCA Ethernet is the queue surface; DOCA Flow is the steering surface, and they are independent libraries.

Example questions this skill answers well

The CLASSES of DOCA Ethernet 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 bring up an RX and TX queue on a representor or physical port?" — worked example: "set up a doca_eth_rxq plus a doca_eth_txq on a single BlueField representor for first-run testing". Answered by the queue-pair lifecycle in TASKS.md ## configure + CAPABILITIES.md ## Capabilities and modes RX / TX object table.
• "Which RX type fits my data shape — regular, cyclic, or managed-recv?" — worked example: "line-rate ingress with fixed-size frames into a pre-allocated buffer ring". Answered by the RX-type taxonomy in CAPABILITIES.md ## Capabilities and modes
  • the capability-query rule (doca_eth_rxq_cap_is_type_supported against a doca_devinfo) in TASKS.md ## configure.
• "How do I send a packet from user code through doca_eth_txq?" — worked example: "allocate a packet doca_buf, attach the payload, submit one send-task, wait for the completion event". Answered by the TX submission shape in CAPABILITIES.md ## Capabilities and modes
  • the property-set workflow in TASKS.md ## modify.
• "My queue is up but no packets arrive — why?" — worked example: "doca_eth_rxq started cleanly but the recv callback never fires". Answered by the steering-dependency rule in CAPABILITIES.md ## Safety policy
  • the env-prep checklist in TASKS.md ## configure step 1, which routes the steering side to doca-flow and the promiscuous-mode side to doca-setup.
• "Is this Ethernet capability available on my device + my installed DOCA?" — worked example: "does this device advertise L3 checksum offload". Answered by the capability-query rule (doca_eth_txq_cap_is_l3_chksum_offload_supported against a doca_devinfo) in CAPABILITIES.md ## Capabilities and modes
  • the version-and-device overlay in CAPABILITIES.md ## Version compatibility.
• "What does this DOCA_ERROR_* from an Ethernet call mean and which layer caused it?" — worked example: "DOCA_ERROR_AGAIN on doca_task_submit for an eth_txq send-task at high rate". Answered by the Ethernet overlay on the cross-library taxonomy in CAPABILITIES.md ## Error taxonomy
  • the layered ladder in TASKS.md ## debug that escalates to doca-debug.

Audience

This skill serves external developers building applications that consume the DOCA Ethernet library — i.e., users whose code calls doca_eth_rxq_* / doca_eth_txq_* (directly in C/C++, or through FFI/bindings from another language) to do line-rate packet I/O on physical ports, representors, or SFs of a BlueField or ConnectX device. It is not for NVIDIA developers contributing to DOCA Ethernet itself.

Language scope. DOCA Ethernet ships as a C library with pkg-config module name doca-eth. The shipped samples are written in C. C and C++ consumers are the canonical case; the worked examples in TASKS.md assume that path. Other-language consumers (Rust, Go, Python, …) consume the same *.so through FFI or language-specific bindings; the skill's contribution in that case is to keep the queue-object split, lifecycle, capability-discovery, permission, RX-type taxonomy, 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 Ethernet work, in any language. Concretely:

• Initializing a doca_eth_rxq on a doca_dev opened against a physical port, a representor, or an SF — choosing among the regular / cyclic / managed-recv RX types based on data shape before doca_ctx_start().
• Initializing a doca_eth_txq on the same or a different doca_dev and posting send-tasks against packet doca_bufs payload buffers.
• Reading or setting Ethernet queue properties via doca_eth_rxq_set_* / doca_eth_txq_set_* and querying device capability via doca_eth_rxq_cap_* / doca_eth_txq_cap_* (max burst size, RX-type support, max scatter-gather length, checksum-offload presence).
• Confirming the port is up and that traffic is actually steered to the chosen RX queue — either via DOCA Flow rules (the canonical path) or via kernel-side promiscuous mode (the expedient first-run path).
• Wiring an Ethernet queue to a higher-level data plane: GPU packet processing via DOCA GPUNetIO, custom user-space forwarding agents, or telemetry mirrors that snap a copy of every packet.
• Debugging a DOCA_ERROR_* returned from an Ethernet call (lifecycle vs. permission vs. capability vs. send-queue-full vs. driver-below) and the per-queue progress engine events.
• Designing or extending non-C bindings (Rust, Go, Python, …) that wrap the DOCA Ethernet C ABI — for the lifecycle, queue split, RX-type, capability, and permission rules the wrapper must honor.

Do not load this skill for general DOCA orientation, install of DOCA itself, flow-rule programming (use doca-flow), host ↔ DPU control messaging (use doca-comch), or RDMA data movement (use doca-rdma). For DOCA documentation orientation, use doca-public-knowledge-map.