MLX driver for host-to-ARM communication
From: Tariq Toukan <tariqt@nvidia.com>
Date: 2026-08-13 08:33:31
Hi, I plan to submit a patch series introducing a new minimalist MLX host-to-ARM communication driver. Could you confirm whether this series can be submitted in parallel with our regular mlx5 feature patches without conflicting with the 15-patch limit? It is to be placed in its own new directory: drivers/net/ethernet/mellanox/mlx5/nodnic/ Find more details below [1]. Regards, Tariq [1] net/mlx5: Introduce mlx5_nodnic driver for BF4 management PF BlueField-4 no longer includes the RSHIM hardware that previous BlueField generations relied on for host-to-ARM communication. In its place, the firmware exposes two dedicated management PFs — one facing the host side and one facing the ARM side — and configures steering rules to loop traffic between them, enabling host-to-ARM communication through standard networking interfaces. Add mlx5_nodnic, a lightweight driver for these management PFs. NODNIC (No DRAM NIC) is a lightweight interface intended to allow simple packet transmission for minimalistic drivers with a low memory footprint. The driver communicates with the firmware through PCI Vendor Specific Capability (VSC) — reads and writes over PCI config space, unlike mlx5_core which uses a DMA-based command interface. Each management PF exposes a single SQ and a single RQ that share one CQ. The interface configures two MSI-Xs: the data MSI-X fires on CQEs, driving both TX and RX completions; the event MSI-X notifies on port state changes, where the firmware brings the port up once both the host and ARM sides have gone up.