HTML rendering created 2025-09-06 byMichael Kerrisk, author ofThe Linux Programming Interface. For details of in-depthLinux/UNIX system programming training courses that I teach, lookhere. Hosting byjambit GmbH. |  |
NAME |SYNOPSIS |DESCRIPTION |ARGUMENTS |RETURN VALUE |AUTHOR |COLOPHON | |
mlx5dv_r.../ dealloc(3) mlx5 Programmer’s Manualmlx5dv_r.../ dealloc(3)mlx5dv_reserved_qpn_alloc - Allocate a reserved QP number from device mlx5dv_reserved_qpn_dealloc - Release the reserved QP number
#include <infiniband/mlx5dv.h> int mlx5dv_reserved_qpn_alloc(struct ibv_context *ctx, uint32_t *qpn); int mlx5dv_reserved_qpn_dealloc(struct ibv_context *ctx, uint32_t qpn);
When work with RDMA_CM RDMA_TCP_PS + external QP support, a client node needs GUID level unique QP numbers to comply with the CM’s timewait logic. If a real unique QP is not allocated, a device global QPN value is required and can be allocated via this interface. The mlx5 DCI QP is such an example, which could connect to the remote DCT’s multiple times as long as the application provides unique QPN for each new RDMA_CM connection. These 2 APIs provide the allocation/deallocation of a unique QP number from/to device. This qpn can be used with DC QPN in RDMA_CM connection establishment, which will comply with the CM timewait kernel logic.
ctx The device context to issue the action on.qpn The allocated QP number (for alloc API), or the QP number to be deallocated (for dealloc API).
0 on success; EOPNOTSUPP if not supported, or other errno value on other failures.
Mark Zhang ⟨markzhang@nvidia.com⟩ Alex Rosenbaum ⟨alexr@nvidia.com⟩
This page is part of therdma-core (RDMA Core Userspace Libraries and Daemons) project. Information about the project can be found at ⟨https://github.com/linux-rdma/rdma-core⟩. If you have a bug report for this manual page, send it to linux-rdma@vger.kernel.org. This page was obtained from the project's upstream Git repository ⟨https://github.com/linux-rdma/rdma-core.git⟩ on 2025-08-11. (At that time, the date of the most recent commit that was found in the repository was 2025-08-04.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which isnot part of the original manual page), send a mail to man-pages@man7.orgmlx5 2020-12-29mlx5dv_r.../ dealloc(3)HTML rendering created 2025-09-06 byMichael Kerrisk, author ofThe Linux Programming Interface. For details of in-depthLinux/UNIX system programming training courses that I teach, lookhere. Hosting byjambit GmbH. | |