doca-gpi

DOCA GPI

Where to start: This skill assumes DOCA is already installed and the user is doing hands-on GPI work on a host that has both a BlueField / ConnectX device and an NVIDIA GPU reachable over PCIe. Open TASKS.md if the user wants to do something (install / configure / build / modify / run / test / debug / use); open CAPABILITIES.md when the question is what can GPI express on this version — the domain + channel object model, the GPU-side handle handoff, the relationship to doca-gpunetio and doca-verbs, the attribute objects, and the safety overlay. If the user has not installed DOCA yet, route to doca-setup first.

Example questions this skill answers well

The CLASSES of GPI 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.

• "Should I use doca-gpi or doca-gpunetio for this case?" — worked example: "my CUDA kernel needs to post RDMA writes directly to a remote DPU's memory — do I want the higher-level Send/Receive surface or the lower-level channel/queue surface?". Answered by the channel-level vs Send/Receive-level selection rule in CAPABILITIES.md ## Capabilities and modes surface-selection table.
• "How do I bring up a GPI channel and connect it to a remote peer?" — worked example: "create the GPI, set domain + channel attribute sizing, create the channel, exchange endpoint connection info with the remote, connect the endpoint". Answered by the channel-object lifecycle in CAPABILITIES.md ## Capabilities and modes
  • the configure walk in TASKS.md ## configure.
• "What is the GPU-side handle and how do I hand it to my CUDA kernel?" — worked example: "doca_gpi_gpu_channel_get returns a doca_gpu_gpi_channel* — how do I get that into my CUDA kernel's argument list?". Answered by the GPU-handoff pattern in CAPABILITIES.md ## Capabilities and modes
  • the run-side wiring in TASKS.md ## run, cross-linked into doca-gpunetio for the CUDA-side programming surface itself.
• "What does my CUDA + GPU + DOCA version stack need to look like?" — worked example: "I have BlueField-3 + A100; which CUDA Toolkit and which DOCA version do I need?". Answered by the version-overlay in CAPABILITIES.md ## Version compatibility
  • the install-checks in TASKS.md ## install.
• "How do I size the channels and work queues I want?" — worked example: "I want 64 channels in a domain, each with a 1024-entry send queue; which setters express that?". Answered by the attribute-object sizing rule (doca_gpi_domain_attr_set_num_channels, doca_gpi_channel_attr_set_sq_wqe_num) in CAPABILITIES.md ## Capabilities and modes
  • the sizing step in TASKS.md ## configure.
• "What does this DOCA_ERROR_* from a doca_gpi_* call mean?" — worked example: "DOCA_ERROR_* from doca_gpi_gpu_channel_get". Answered by the GPI 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 GPU-resident DOCA applications that need to drive RDMA queues directly from CUDA kernels — i.e., users whose accelerator-side code wants to post RDMA work from GPU memory without round-tripping through the host CPU. The canonical caller is a CUDA kernel that runs on an NVIDIA GPU on the same host as a BlueField / ConnectX device, has GPUDirect-style access to the DPU's RDMA queues through the DOCA GPU-NetIO stack, and uses the GPI channel + queue handle to drive RDMA initiation. This skill is not for NVIDIA developers contributing to DOCA GPI itself, and it is not the right surface for the higher-level Send/Receive Ethernet-shaped GPU NetIO API — that belongs to doca-gpunetio.

Language scope

DOCA GPI ships as a C library with the pkg-config module name doca-gpi. The library's host-side surface (doca_gpi_*) is C; the GPU-side surface — the doca_gpu_gpi_channel* handle and the device-side calls a CUDA kernel uses against that handle — is compiled with nvcc against the DOCA GPU NetIO device-side header set documented in doca-gpunetio. Other-language consumers (Rust, Go, Python, …) consume the host-side *.so through FFI; the skill's contribution in that case is to keep the channel / queue lifecycle, the GPU-handle handoff, the version discipline, and the safety overlay language-neutral, and to route the agent to the public C ABI as the authoritative surface that any wrapper will eventually call. The GPU-side surface is not wrappable in another language — it is compiled and linked into the CUDA binary itself.

When to load this skill

Load this skill when the user is doing hands-on DOCA GPI work on a host with both a BlueField / ConnectX device and an NVIDIA GPU. Concretely:

• Deciding between doca-gpi (the lower-level channel/queue surface) and doca-gpunetio (the higher-level Send/Receive surface) for a new GPU-initiated RDMA workload.
• Creating a doca_gpi on a doca_dev, configuring it via the doca_gpi_set_* family (domain count, GID index, port) and sizing domains and channels through the doca_gpi_domain_attr_* / doca_gpi_channel_attr_* setters before doca_gpi_start().
• Creating a channel with doca_gpi_channel_create and retrieving its GPU-side handle with doca_gpi_gpu_channel_get, then handing the GPU-side handle to a CUDA kernel.
• Exchanging endpoint connection info with a remote peer using doca_gpi_channel_ep_conn_info_create / doca_gpi_channel_ep_connect to establish the GPU-driven channel end-to-end.
• Attaching memory regions to a GPI domain with doca_gpi_domain_attach_local_mmap / doca_gpi_domain_attach_remote_mmap (each backed by a doca_mmap the application created).
• Debugging a DOCA_ERROR_* returned by a doca_gpi_* call and deciding whether the cause is a lifecycle ordering bug, a GPU datapath mis-assignment, a CUDA-version mismatch, or a layer below DOCA.

Do not load this skill for general DOCA orientation, install of DOCA itself, host-CPU-initiated RDMA, or the higher-level GPU NetIO Send/Receive Ethernet-shaped API. For those, use doca-public-knowledge-map, doca-setup, doca-rdma, and doca-gpunetio respectively. When one question spans the GPI channel lifecycle and CUDA-side GPU NetIO behavior, load both skills: this skill owns GPI object creation, connection, and teardown, while doca-gpunetio owns kernel launch and device-side execution. If that boundary remains ambiguous after reading both scopes, stop and ask which side is failing instead of choosing one implicitly.

What this skill provides

This is a thin loader. The body keeps only the orientation needed to pick the right next file. The substantive GPI-specific material lives in two companion files:

• CAPABILITIES.md — what GPI can express on this version: the doca_gpi / doca_gpi_domain / doca_gpi_channel object model, the GPU-side handle handoff, the relationship to doca-gpunetio (which owns the GPU-side doca_gpu_gpi_channel* device surface) and to doca-verbs and doca-dpa (the transport and DPA layers GPI builds on), the domain and channel attribute objects, the maturity statement (every doca_gpi_* symbol is DOCA_EXPERIMENTAL), the GPI overlay on the cross-library DOCA_ERROR_* taxonomy, the observability surface (CUDA-side channel polling, mmap-attach exchange), and the safety policy that gates GPU-side RDMA initiation.
• TASKS.md — step-by-step workflows for the eight in-scope verbs: install, configure, build, modify, run, test, debug, use. 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 CUDA Toolkit compatible with the installed DOCA is present, and the user has the privileges their public install profile expects. It does not cover installing DOCA — that path goes through doca-setup.

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 GPI application source code, in any language. The agent's job is to route the user to verified reference code (the shipped DOCA GPU-NetIO samples on the installed package set are the canonical worked examples for the GPU-side handoff) and to prescribe a minimum-diff modification via the universal modify-a-sample workflow in doca-programming-guide. Because every GPI symbol is tagged DOCA_EXPERIMENTAL in the public header, the skill refuses to author GPI source from documentation prose.
• Standalone build manifests (meson.build, CMakeLists.txt, Cargo.toml, …) parked inside the skill. The agent constructs the build manifest in the user's project directory against the user's installed DOCA, where pkg-config --modversion doca-gpi is the source of truth.
• CUDA kernel templates. The CUDA-side surface is owned by doca-gpunetio; GPI's GPU-side handle is consumed by the CUDA programming model documented there. This skill names the GPI-specific handoff (the doca_gpu_gpi_channel* type, the channel-connect call) but does not author CUDA kernels.
• 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.

Loading order

1. Read this SKILL.md first to confirm the user's question is in scope.
2. For the GPI object model, the GPU-side handoff pattern, the domain and channel attribute objects, the version compatibility rule, the error taxonomy, observability, and safety policy, see CAPABILITIES.md.
3. For step-by-step workflows — install, configure, build, modify, run, test, debug, use — see TASKS.md.

Both companion files cross-link to each other and to doca-public-knowledge-map whenever the right answer is "look it up in the public docs or the installed package layout" rather than "GPI-specific guidance".

Related skills

• doca-gpunetio — the GPU NetIO library that exposes Send/Receive-shaped Ethernet I/O for CUDA kernels and owns the GPU-side device surface GPI hands off to: the doca_gpu_gpi_channel* type and its device-side .cuh API live in doca-gpunetio, and doca_gpi.h includes doca_gpunetio.h. Both can coexist in the same application. The selection table in CAPABILITIES.md ## Capabilities and modes is the load-bearing decision aid.
• doca-verbs and doca-dpa — the transport and DPA layers GPI builds on. dependencies/meson.build lists doca-dpa, doca-gpunetio, and doca-verbs (plus the libmlx5 / libibverbs externals); doca_gpi_get_dpa returns the GPI-owned doca_dpa* for tuning DPA attributes. The RDMA transport type, GID / port selection, and permission semantics live at the verbs layer; GPI consumes it rather than binding a doca-rdma queue.
• doca-rdmi — the sister DPA-side initiator surface. Both GPI and RDMI exist for "drive RDMA initiation from an accelerator without the host CPU on the data path"; GPI is the GPU case, RDMI is the DPA case.
• doca-public-knowledge-map — the routing table for every public DOCA documentation source and the on-disk layout of an installed DOCA package.
• doca-setup — env preparation, install verification, and the I have no install yet path with the public NGC DOCA container.
• doca-programming-guide — 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. This skill layers GPI specifics on top.
• doca-debug — the cross-cutting debug ladder (install / version / build / link / runtime / program / driver). GPI-specific debug overlays on top of it.
• doca-hardware-safety — the bundle-wide hardware-safety meta-policy. The ## Safety policy overlay in CAPABILITIES.md cross-links it.
• doca-version — the version detection / four-way match rule every per-artifact ## Version compatibility anchor builds on. This skill quotes the GPI-specific overlay only (DOCA-side .pc PLUS the CUDA Toolkit axis).
• doca-structured-tools-contract — the JSON-schema contracts for the agent-preferred structured helpers; the ## Command appendix in TASKS.md defers to them before falling back to the manual chain.*