ibv_reg_mr(3) — Linux manual page


IBV_REG_MR(3)        Libibverbs Programmer's Manual        IBV_REG_MR(3)

NAME         top

       ibv_reg_mr, ibv_reg_mr_iova, ibv_reg_dmabuf_mr, ibv_dereg_mr -
       register or deregister a memory region (MR)

SYNOPSIS         top

       #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);

DESCRIPTION         top

       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_FLUSH_GLOBAL Enable Remote Flush Operation with global
       visibility placement type (if supported)

       IBV_ACCESS_FLUSH_PERSISTENT Enable Remote Flush Operation with
       persistence placement type (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

       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_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_dereg_mr() deregisters the MR mr.

RETURN VALUE         top

       ibv_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).

NOTES         top

       ibv_dereg_mr() fails if any memory window is still bound to this

SEE ALSO         top

       ibv_alloc_pd(3), ibv_post_send(3), ibv_post_recv(3),

AUTHORS         top

       Dotan Barak <dotanba@gmail.com>

COLOPHON         top

       This page is part of the rdma-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 2023-06-23.  (At
       that time, the date of the most recent commit that was found in
       the repository was 2023-06-14.)  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 is not part of the original manual page), send a mail to

libibverbs                     2006-10-31                  IBV_REG_MR(3)

Pages that refer to this page: ibv_alloc_mw(3)ibv_alloc_pd(3)ibv_bind_mw(3)rdma_dereg_mr(3)rdma_post_recv(3)rdma_post_recvv(3)rdma_reg_msgs(3)rdma_reg_read(3)rdma_reg_write(3)