Ubuntu Manpage: ibv_reg_mr, ibv_reg_mr_iova, ibv_dereg_mr - register or deregister a memory region (MR)

Provided by: libibverbs-dev_28.0-1ubuntu1_amd64

NAME

       ibv_reg_mr, ibv_reg_mr_iova, 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);

       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_dereg_mr() deregisters the MR mr.

RETURN VALUE

       ibv_reg_mr()  /  ibv_reg_mr_iova()  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.

AUTHORS