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>