IBV_REG_MR
Section: Libibverbs Programmer's Manual (3)
Updated: 2006-10-31
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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_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 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>
-
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- NOTES
-
- SEE ALSO
-
- AUTHORS
-
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