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IBV_REG_MR(3) Libibverbs Programmer's Manual IBV_REG_MR(3) NAME ibv_reg_mr, ibv_dereg_mr - register or deregister a memory region (MR) SYNOPSIS #include <infiniband/verbs.h> struct ibv_mr *ibv_reg_mr(struct ibv_pd *pd, void *addr, size_t length, int access); int ibv_dereg_mr(struct ibv_mr *mr); DESCRIPTION ibv_reg_mr() registers a memory region (MR) associated with the protection domain pd. The MR's starting address is addr and its size is length. The argument access describes the desired memory protection attributes; it is either 0 or the bitwise OR of one or more of the following flags: IBV_ACCESS_LOCAL_WRITE Enable Local Write Access IBV_ACCESS_REMOTE_WRITE Enable Remote Write Access IBV_ACCESS_REMOTE_READ Enable Remote Read Access IBV_ACCESS_REMOTE_ATOMIC Enable Remote Atomic Operation Access (if supported) IBV_ACCESS_MW_BIND Enable Memory Window Binding IBV_ACCESS_ON_DEMAND Create an on-demand paging MR If IBV_ACCESS_REMOTE_WRITE or IBV_ACCESS_REMOTE_ATOMIC is set, then IBV_ACCESS_LOCAL_WRITE must be set too. Local read access is always enabled for the MR. ibv_dereg_mr() deregisters the MR mr. RETURN VALUE ibv_reg_mr() returns a pointer to the registered MR, or NULL if the request fails. The local key (L_Key) field lkey is used as the lkey field of struct ibv_sge when posting buffers with ibv_post_* verbs, and the the remote key (R_Key) field rkey is used by remote processes to perform Atomic and RDMA operations. The remote process places this rkey as the rkey field of struct ibv_send_wr passed to the ibv_post_send function. ibv_dereg_mr() returns 0 on success, or the value of errno on failure (which indicates the failure reason). NOTES ibv_dereg_mr() fails if any memory window is still bound to this MR. SEE ALSO ibv_alloc_pd(3), ibv_post_send(3), ibv_post_recv(3), ibv_post_srq_recv(3)