Provided by: libibverbs-dev_50.0-2build2_amd64 
NAME
ibv_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);
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_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
This setting allows the NIC to relax the order that data is transfered between the network and the
target memory region. Relaxed ordering allows network initiated writes (such as incoming message
send or RDMA write operations) to reach memory in an arbitrary order. This can improve the
performance of some applications. However, relaxed ordering has the following impact: RDMA write-
after-write message order is no longer guaranteed. (Send messages will still match posted receive
buffers in order.) Back-to-back network writes that target the same memory region leave the
region in an unknown state. Relaxed ordering does not change completion semantics, such as data
visibility. That is, a completion still ensures that all data is visible, including data from
prior transfers. Relaxed ordered operations will also not bypass atomic operations.
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 VALUE
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
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)
AUTHORS
Dotan Barak <dotanba@gmail.com>