IBV_REG_MR - Online Linux Manual PageSection : 3
Updated : 2006-10-31
Source : libibverbs
Note : Libibverbs Programmer's Manual
NAMEibv_reg_mr, ibv_reg_mr_iova, ibv_reg_dmabuf_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); struct ibv_mr *ibv_reg_mr_iova(struct ibv_pd *pd, void *addr, size_t length, uint64_t hca_va, int access); struct ibv_mr *ibv_reg_dmabuf_mr(struct ibv_pd *pd, uint64_t offset, size_t length, uint64_t iova, int fd, int access); int ibv_dereg_mr(struct ibv_mr *mr);
DESCRIPTIONibv_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_ZERO_BASED Use byte offset from beginning of MR to access this MR, instead of a pointer address  IBV_ACCESS_ON_DEMAND Create an on-demand paging MR  IBV_ACCESS_HUGETLB Huge pages are guaranteed to be used for this MR, applicable with IBV_ACCESS_ON_DEMAND in explicit mode only  IBV_ACCESS_RELAXED_ORDERING Allow system to reorder accesses to the MR to improve performance  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. To create an implicit ODP MR, IBV_ACCESS_ON_DEMAND should be set, addr should be 0 and length should be SIZE_MAX. If IBV_ACCESS_HUGETLB is set, then application awares that for this MR all pages are huge and must promise it will never do anything to break huge pages. ibv_reg_mr_iova() ibv_reg_mr_iova is the same as the normal reg_mr, except that the user is allowed to specify the virtual base address of the MR when accessed through a lkey or rkey. The offset in the memory region is computed as 'addr + (iova - hca_va)'. Specifying 0 for hca_va has the same effect as IBV_ACCESS_ZERO_BASED. ibv_reg_dmabuf_mr() registers a dma-buf based memory region (MR) associated with the protection domain pd. The MR starts at offset of the dma-buf and its size is length. The dma-buf is identified by the file descriptor fd. The argument iova specifies the virtual base address of the MR when accessed through a lkey or rkey. It must have the same page offset as offset. The argument access describes the desired memory protection attributes; it is similar to the ibv_reg_mr case except that only the following flags are supported: IBV_ACCESS_LOCAL_WRITE, IBV_ACCESS_REMOTE_WRITE, IBV_ACCESS_REMOTE_READ, IBV_ACCESS_REMOTE_ATOMIC, IBV_ACCESS_RELAXED_ORDERING. ibv_dereg_mr() deregisters the MR mr.
RETURN VALUEibv_reg_mr() / ibv_reg_mr_iova() / ibv_reg_dmabuf_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).
NOTESibv_dereg_mr() fails if any memory window is still bound to this MR.
SEE ALSOibv_alloc_pd(3), ibv_post_send(3), ibv_post_recv(3), ibv_post_srq_recv(3)
AUTHORSDotan Barak <dotanba@gmail.com> 0
Johanes Gumabo
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