IBV_REG_MR(3) Libibverbs Programmer's Manual IBV_REG_MR(3)
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 protec-
tion 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 fol-
lowing 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 sup-
ported)
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, ex-
cept 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) asso-
ciated 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 mem-
ory 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_RE-
MOTE_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 oper-
ations. 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>
libibverbs 2006-10-31 IBV_REG_MR(3)
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