NAME

       ibv_alloc_mw, ibv_dealloc_mw - allocate or deallocate a memory window (MW)

SYNOPSIS

       #include <infiniband/verbs.h>

       struct ibv_mw *ibv_alloc_mw(struct ibv_pd *pd,
                                   enum ibv_mw_type type);

       int ibv_dealloc_mw(struct ibv_mw *mw);

DESCRIPTION

       ibv_alloc_mw() allocates a memory window (MW) associated with the protection domain pd.  The MW's type (1
       or 2A/2B) is type.

       The MW is created not bound. For it to be useful, the MW must be bound, through either ibv_bind_mw  (type
       1)  or  a  special WR (type 2).  Once bound, the memory window allows RDMA (remote) access to a subset of
       the MR to which it was bound, until invalidated by:  ibv_bind_mw  verb  with  zero  length  for  type  1,
       IBV_WR_LOCAL_INV/IBV_WR_SEND_WITH_INV WR opcode for type 2, deallocation.

       ibv_dealloc_mw() Unbinds in case was previously bound and deallocates the MW mw.

RETURN VALUE

       ibv_alloc_mw()  returns  a  pointer  to  the  allocated MW, or NULL if the request fails.  The remote key
       (R_Key) field rkey is used by remote processes to perform Atomic and RDMA operations. This  key  will  be
       changed  during  bind  operations.  The  remote  process  places  this  rkey  as the rkey field of struct
       ibv_send_wr passed to the ibv_post_send function.

       ibv_dealloc_mw() 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_bind_mw(3), ibv_reg_mr(3),

AUTHORS

       Majd Dibbiny <majd@mellanox.com>

       Yishai Hadas <yishaih@mellanox.com>