Mellanox ConnectX-3 InfiniBand and RoCE HCA support (mlx4_ib)
The InfiniBand and RoCE (RDMA over Ethernet) side of Mellanox's ConnectX-3 and ConnectX-3 Pro host channel adapters, a generation of high-speed datacenter NICs from the early-to-mid 2010s widely deployed in HPC clusters, storage fabrics, and enterprise virtualization hosts. It provides the RDMA verbs interface that lets these cards do low-latency InfiniBand or 10/40/56 Gb Ethernet RoCE traffic.
recommendation
Worth keeping but documenting its niche. ConnectX-3 and ConnectX-3 Pro are now classified as legacy by NVIDIA and no longer appear on the current adapter line-up, yet the installed base is substantial and upstream fixes are still landing in 2026. Newer Mellanox/NVIDIA RDMA hardware is handled by the separate mlx5_ib driver, so mlx4_ib cannot simply be dropped without stranding existing ConnectX-3 deployments.
repository signals
sources
- lore.kernel.org
linux-rdma carried an April 6, 2026 patch touching drivers/infiniband/hw/mlx4/main.c, showing current upstream maintenance rather than abandonment.
- cateee.net
LKDDb lists CONFIG_MLX4_INFINIBAND as 'Mellanox ConnectX HCA support', building module mlx4_ib, and present through 6.19-rc+HEAD.
- docs.nvidia.com
NVIDIA's December 2, 2025 MFT documentation lists ConnectX-3/ConnectX-3 Pro under 'supported legacy HCAs', not the main current adapter list.
- docs.nvidia.com
NVIDIA's February 23, 2026 MFT documentation places ConnectX-3 and ConnectX-3 Pro in 'Group I/4th Generation', separate from newer ConnectX-4/5/6/7 hardware.
- nvidia.com
NVIDIA's current ConnectX NIC product page markets ConnectX-6 Lx, ConnectX-6 Dx, ConnectX-7 and SuperNIC products, indicating current new-sales focus has moved beyond mlx4-generation hardware.
codex reasoning notes (technical)
`lore_file_timeline` and `lore_activity` on drivers/infiniband/hw/mlx4/main.c showed steady activity through April 6, 2026; source URL taken from lore_activity output. `lore_regex` for removal/deprecation subjects timed out once and was not retried, so I only claim positive maintenance evidence, not a proven absence of removal discussion. `web.search_query` + `open` obtained the LKDDb and NVIDIA docs URLs: LKDDb confirms the driver is still in-tree, while NVIDIA docs classify ConnectX-3/3 Pro as legacy and the live product page highlights newer ConnectX generations. Recommendation is `keep-annotate`: hardware is legacy and likely absent from mainstream new 2025 deployments, but installed-base usage and upstream fix traffic remain real. `mlx5_ib` is the natural replacement for newer Mellanox/NVIDIA RDMA HCAs, though it does not drive the same PCI IDs.