Amazon Elastic Fabric Adapter (EFA) RDMA driver
Amazon's Elastic Fabric Adapter is a PCIe RDMA-capable network device built into many EC2 instance types for high-performance computing, distributed training, and other low-latency workloads. It provides OS-bypass messaging for MPI and NCCL applications running across AWS clusters, complementing (not replacing) the regular ENA Ethernet interface.
recommendation
It should stay in the kernel because EFA is the RDMA fabric Amazon exposes on current EC2 HPC and AI/ML instance types, and Amazon engineers are still landing feature work upstream in 2025-2026 (completion counters, AH usage counter sysfs exposure). There is no replacement driver, since the related ENA driver only handles ordinary IP networking, not the low-latency RDMA path EFA provides.
repository signals
sources
- lore.kernel.org
Upstream activity is current: linux-rdma carried a 2026-04 EFA feature series adding completion counters, indicating active maintenance rather than retirement.
- lore.kernel.org
A separate 2026-02 EFA patch adds AH usage counter sysfs exposure, showing multiple active Amazon authors and ongoing feature work.
- docs.aws.amazon.com
AWS documents EFA as a current EC2 networking product for AI/ML and HPC, with a long list of supported instance types, so it is still offered for new deployments in 2025/2026.
codex reasoning notes (technical)
Real PCI RDMA driver: Kconfig names 'Amazon Elastic Fabric Adapter (EFA) support' and efa_main.c declares Amazon PCI IDs. lore_activity on drivers/infiniband/hw/efa/efa_main.c returned multiple 2025-2026 feature patches (URLs cited), so there is clear active upstream attention and no removal signal in the gathered lore evidence; an attempted lei lore query for removal/deprecation terms failed due local socket sandboxing, so absence of removal talk is inferred from the active patch stream plus the provided recent-touch metadata. AWS EFA product/support status was obtained by web.open on the canonical EC2 User Guide URL, which shows EFA as a current service with many supported instance families. Because EFA is AWS-specific RDMA hardware/interface, there is no like-for-like upstream replacement driver; ENA is complementary IP networking, not a replacement for EFA's RDMA/HPC role.