Chapter 7. Configuring Soft-iWARP Remote Direct Memory Access (RDMA) uses several libraries and protocols over an Ethernet such as iWARP, Soft-iWARP for performance improvement and aided programming interface. Important The Soft-iWARP feature is deprecated and will be removed in RHEL 10. Soft-iWARP is a Technology Preview feature only. Technology Preview features are not supported with Red Hat production service level agreements (SLAs) and might not be functionally complete. Red Hat does not recommend using them in production. These features provide early access to upcoming product features, enabling customers to test functionality and provide feedback during the development process. For more information about the support scope of Red Hat Technology Preview features, see https://access.redhat.com/support/offerings/techpreview . 7.1. Overview of iWARP and Soft-iWARP Remote direct memory access (RDMA) uses the iWARP over Ethernet for converged and low latency data transmission over TCP. By using standard Ethernet switches and the TCP/IP stack, iWARP routes traffic across the IP subnets to utilize the existing infrastructure efficiently. In Red Hat Enterprise Linux, multiple providers implement iWARP for their hardware network interface cards. For example, cxgb4 , irdma , qedr , and so on. Soft-iWARP (siw) is a software-based iWARP kernel driver and user library for Linux. It is a software-based RDMA device that provides a programming interface to RDMA hardware when attached to network interface cards. It provides an easy way to test and validate the RDMA environment. 7.2. Configuring Soft-iWARP Soft-iWARP (siw) implements the iWARP Remote direct memory access (RDMA) transport over the Linux TCP/IP network stack. It enables a system with a standard Ethernet adapter to interoperate with an iWARP adapter or with another system running the Soft-iWARP driver or a host with the hardware that supports iWARP. Important The Soft-iWARP feature is deprecated and will be removed in RHEL 10. The Soft-iWARP feature is provided as a Technology Preview only. Technology Preview features are not supported with Red Hat production Service Level Agreements (SLAs), might not be functionally complete, and Red Hat does not recommend using them for production. These previews provide early access to upcoming product features, enabling customers to test functionality and provide feedback during the development process. See Technology Preview Features Support Scope on the Red Hat Customer Portal for information about the support scope for Technology Preview features. To configure Soft-iWARP, you can use this procedure in a script to run automatically when the system boots. Prerequisites An Ethernet adapter is installed Procedure Install the iproute , libibverbs , libibverbs-utils , and infiniband-diags packages: Display the RDMA links: Load the siw kernel module: Add a new siw device named siw0 that uses the enp0s1 interface: Verification View the state of all RDMA links: List the available RDMA devices: You can use the ibv_devinfo utility to display a detailed status:

Commands:
dnf install iproute libibverbs libibverbs-utils infiniband-diags
rdma link show
modprobe siw
rdma link add siw0 type siw netdev enp0s1
rdma link show link siw0/1 state ACTIVE physical_state LINK_UP netdev enp0s1
ibv_devices device node GUID ------ ---------------- siw0 0250b6fffea19d61
ibv_devinfo siw0 hca_id: siw0 transport: iWARP (1) fw_ver: 0.0.0 node_guid: 0250:b6ff:fea1:9d61 sys_image_guid: 0250:b6ff:fea1:9d61 vendor_id: 0x626d74 vendor_part_id: 1 hw_ver: 0x0 phys_port_cnt: 1 port: 1 state: PORT_ACTIVE (4) max_mtu: 1024 (3) active_mtu: 1024 (3) sm_lid: 0 port_lid: 0 port_lmc: 0x00 link_layer: Ethernet