/doca-caps

DOCA Capabilities Print Tool — Capabilities

Where to start: doca_caps is a single CLI binary; the pattern overview below names the recurring doca_caps-class questions. Pick the pattern first, then drill into the H2 that owns the substance. For the how of executing each pattern, jump to TASKS.md.

This file is loaded by SKILL.md. It documents what doca_caps is, what it reports, what versions it ships in, what its narrow error and observability surfaces look like, and the read-only safety posture that makes it the canonical first step in other skills' workflows. For step-by-step invocations and the capability-snapshot workflow, see TASKS.md.

Pattern overview

Every doca_caps-class question this skill teaches resolves into one of FIVE patterns. The patterns are CLASSES — they apply across every DOCA install, not just one specific platform.

Two cross-cutting rules that apply to every pattern above:

• Read-only always; never recommend a state-changing alternative. doca_caps is uniquely safe to run early in any DOCA workflow. The agent must not propose a state-changing workaround when doca_caps answers the question.
• Empty output is an answer, not a failure. When doca_caps prints nothing for a capability the user asked about, the answer is "this device on this DOCA version does not expose that capability". The agent must report that conclusion, not retry the invocation hoping for different output.

Capabilities and modes

doca_caps is shipped as a single read-only CLI binary at /opt/mellanox/doca/tools/doca_caps on every DOCA install (host or BlueField Arm) since DOCA 2.6.0. There is no daemon, no library to link against, and no programmatic API. The user's entire interaction model is invoke the binary, read the printed output.

The tool reports five documented capability families, per the public DOCA Capabilities Print Tool guide:

1. DOCA device list — for every DOCA device, prints the PCIe address and per-device attributes (ibdev_name, iface_name, iface_index, pci_func_type (PF / VF / SF), uplink_ib_port, mac_addr, ipv4_addr, ipv6_addr).
2. DOCA representor device list — for every DOCA device, prints the PCIe address of every available DOCA representor and per-representor attributes (ib_port, host_index, pf_index, vf_index, pci_func_type, hotplug, vuid, iface_name, iface_index).
3. DOCA library list (CLI flag: --list-libs) — prints the DOCA libraries supported by the running OS and their availability for specific OS targets. This is the documented authoritative answer to "which DOCA libraries does this install actually support on my OS?"
4. DOCA library capabilities — for every DOCA device, prints the capabilities it supports in every DOCA library. This is the documented authoritative answer to "can DOCA library X actually do Y on this device?"
5. DOCA logger list (CLI flag: --list-loggers) — prints the available logger names of DOCA libraries. Useful when configuring doca_log_* filters.

The flags the binary registers in tools/caps/main.c are --list-devs, --list-rep-devs, --list-libs, --list-loggers, --pci-addr (scope to a single PCIe address), and --lib. Any of the --list-* flags above can be combined with --pci-addr / --lib to narrow the output. The exact, current flag inventory and example output live in the public guide and in the tool's own --help on the installed version — see TASKS.md ## run.

The tool has no execution modes beyond the flag-driven selection of which capability family to print. There is no --watch, no streaming subscription, no JSON output mode in the documented surface; if a feature like that lands in a future DOCA release, treat the public guide and --help as ground truth and do not assume legacy generic-CLI flags work.

Version compatibility

For the canonical DOCA version-detection chain, the four-way match rule, NGC container semantics, and the headers-win-over-docs rule, see doca-version. The body lives there; this skill does not duplicate it.

The doca_caps-specific overlay is:

• doca_caps is available since DOCA 2.6.0. On older installs the binary is not present; the right answer for "I can't find doca_caps" is to confirm the installed version per doca-version TASKS.md ## configure and, if < 2.6.0, route to doca-setup for an upgrade rather than recommending alternative tools.
• Where it runs: on the x86 / Arm host that has DOCA installed, or on the BlueField Arm side. Same binary, same flags; the set of devices it sees differs by execution context.
• Output format stability: the documented capability families (the five listed in ## Capabilities and modes) are stable across the recent DOCA train. The exact textual / column layout of the output is not contractually frozen — agents that need to consume the output programmatically should prefer the structured doca-capability-snapshot helper per doca-structured-tools-contract when present, and re-verify the textual layout against the user's installed version when absent.
• Per-OS library support: capability family 3 ("DOCA library list") explicitly varies with the OS the install runs on; do not copy a library-availability claim from one host to another.

Error taxonomy

doca_caps's error surface is narrow because the tool is read-only, takes no configuration, and does no orchestration. The error layers the agent should distinguish, in escalating order:

1. Tool-not-installed. doca_caps does not exist at /opt/mellanox/doca/tools/doca_caps. Causes (distinguish before routing):
   • (a) DOCA is not installed on this host at all — pkg-config --modversion doca-common errors with Package 'doca-common' was not found. Routing: full install via doca-setup ## install.
   • (b) The install is < DOCA 2.6.0 (the first release that ships doca_caps). pkg-config --modversion doca-common returns 2.5.x or earlier. Routing: upgrade to ≥ 2.6.0, or use the per-library doca_<library>_cap_* C API as the cap-discovery surface until upgraded.
   • (c) Partial install on a host that DOES have doca-common — pkg-config --modversion doca-common returns a version ≥ 2.6.0 but the per-tool package that ships doca_caps (on DOCA 3.3+ this is the granular doca-caps package; on older releases it shipped via the legacy doca-tools meta-package that no longer exists on 3.3+) was not installed alongside doca-common. This is the most common cause on lab boxes and CI containers that pinned a minimal install. Confirm via: pkg-config --modversion doca-common succeeds AND ls /opt/mellanox/doca/tools/doca_caps errors. Routing: confirm the package name with apt-cache policy doca-caps FIRST, then run apt install doca-caps (or, on older releases, the legacy apt install doca-tools) — NOT a full doca-all reinstall, and NOT a version downgrade. See doca-version CAPABILITIES.md ## Version compatibility partial-install table.
   • (c2) Package installed, binary off-PATH (DOCA 3.3+ default). dpkg -l doca-caps shows the package as ii AND ls /opt/mellanox/doca/tools/doca_caps succeeds, but command -v doca_caps and a bare doca_caps --version both report "not found." On DOCA 3.3+, per-tool binaries land under /opt/mellanox/doca/tools/ and are NOT symlinked into /usr/bin/. This is NOT a partial install — it is a $PATH hygiene issue. Routing: invoke by absolute path (/opt/mellanox/doca/tools/doca_caps --version) or extend PATH (export PATH=/opt/mellanox/doca/tools:$PATH) once at the start of the session. Do NOT re-apt install.
   • (d) The install path was changed by the operator. Confirm via pkg-config --variable=prefix doca-common and check whether doca_caps exists under that prefix's tools/. Routing: ask the operator for the correct path or restore the canonical install layout.
2. Permission / driver layer. Tool runs but cannot enumerate devices because the underlying driver stack (mlx5_core, IB stack, etc.) is not loaded, the user lacks the privileges the install profile expects, or the BlueField mode is incompatible with the requested capability family. The tool's own message (and dmesg for the driver layer) is ground truth; do not guess.
3. Empty / partial output, no error. The tool exits 0 but reports zero devices or a representor list shorter than the operator expects. Cause: no DOCA-supported devices on this host (e.g. the public NGC DOCA container with no PCIe passthrough), or the device the user expected is excluded by the chosen --pci-addr scope. This is a capability-snapshot finding, not a tool failure — route the answer to the consumer of the snapshot (doca-setup ## test or doca-programming-guide ## debug).
4. Library-capability mismatch. Tool runs successfully and prints capabilities, but the user is asking "why does library X say it doesn't support feature Y on my device?". That question belongs in the matching libs/<library> skill — doca_caps only reports the coarse per-device per-library capability surface, not the library-internal reasoning.

doca_caps does not participate in the cross-library DOCA_ERROR_* taxonomy that DOCA libraries return through their C API; it is a CLI, not a library call. For that taxonomy and the program-side debug order, see doca-programming-guide CAPABILITIES.md ## Error taxonomy.

Observability

doca_caps is itself an observability primitive for the rest of the bundle — it is what other skills load to observe the install and the hardware before doing anything that changes state. Specifically:

• doca-setup ## test prescribes running doca_caps --list-devs (and --list-rep-devs where representors are in scope) as the documented install smoke-test.
• doca-programming-guide ## debug prescribes running doca_caps early and preserving its output as a capability snapshot so subsequent debug steps have ground truth instead of guesses.
• The matching libs/<library> skills (e.g. doca-flow CAPABILITIES.md ## Capabilities and modes) point back at doca_caps as the documented source of coarse per-device per-library capability claims, while reserving fine-grained library-internal capability checks for the library's own programmatic API.

The tool does not emit metrics, traces, or logs of its own beyond the printed output. For the program-side observability surface (DOCA log levels, doca_log_*, DOCA_LOGGER_* env vars) see doca-programming-guide CAPABILITIES.md ## Observability.

Safety policy

Overlay on the bundle-wide hardware-safety meta-policy. The rules below are this skill's per-artifact overlay on the cross-cutting rules in doca-hardware-safety CAPABILITIES.md ## Safety policy (specifically ### Per-artifact overlay pattern). When the two layers disagree, the stricter wins; when either layer says STOP, the agent stops.

doca_caps is the safest tool the bundle prescribes:

• Read-only. The tool prints; it does not configure, allocate, claim, or modify any DOCA, kernel, firmware, or device state. This property is what makes it the canonical first step before any workflow that does mutate state.
• No persistent side effects on the host. No files written to /etc, no daemons started, no devices reserved. Re-running it is free.
• Safe to run inside the public NGC DOCA container. Because it takes no configuration and writes nothing, an agent can run it as the very first action even on a host where the operator has not yet decided whether to keep DOCA installed; running it inside the NGC container is the documented zero-install path.
• Quote what the tool said. Do not paraphrase capability claims. If the user later asks "does my setup support feature Y?", the correct answer is to point at the line of the snapshot that says so. If the snapshot does not show feature Y, the answer is "this install / device combination does not report support for Y" — not "it should work, try it".
• Do not invent flags. The documented invocations are the authoritative surface. If the user asks for an output format or a flag the public guide does not list, the safe answer is "the installed --help is the source of truth — let me check it there", not a guess based on generic CLI conventions.

Public-source pointer

The single canonical public source for doca_caps is the DOCA Capabilities Print Tool page on docs.nvidia.com, reachable through doca-public-knowledge-map ## DOCA tools. Do not invent flags, output formats, or capability families beyond what that page documents.