# ibv_create_qp

## NAME



           ibv_create_qp, ibv_destroy_qp - create or destroy a queue pair
           (QP)
    


## SYNOPSIS



           **#include <infiniband/verbs.h>**
    
           **struct ibv_qp *ibv_create_qp(struct ibv_pd** _*pd_**,**
                                        **struct ibv_qp_init_attr** _*qp_init_attr_**);**
    
           **int ibv_destroy_qp(struct ibv_qp** _*qp_**);**
    


## DESCRIPTION



           **ibv_create_qp()** creates a queue pair (QP) associated with the
           protection domain _pd_.  The argument _qp_init_attr_ is an
           ibv_qp_init_attr struct, as defined in <infiniband/verbs.h>.
    
           struct ibv_qp_init_attr {
                   void                   *qp_context;     /* Associated context of the QP */
                   struct ibv_cq          *send_cq;        /* CQ to be associated with the Send Queue (SQ) */
                   struct ibv_cq          *recv_cq;        /* CQ to be associated with the Receive Queue (RQ) */
                   struct ibv_srq         *srq;            /* SRQ handle if QP is to be associated with an SRQ, otherwise NULL */
                   struct ibv_qp_cap       cap;            /* QP capabilities */
                   enum ibv_qp_type        qp_type;        /* QP Transport Service Type: IBV_QPT_RC, IBV_QPT_UC, IBV_QPT_UD, IBV_QPT_RAW_PACKET or IBV_QPT_DRIVER */
                   int                     sq_sig_all;     /* If set, each Work Request (WR) submitted to the SQ generates a completion entry */
           };
    
           struct ibv_qp_cap {
                   uint32_t                max_send_wr;    /* Requested max number of outstanding WRs in the SQ */
                   uint32_t                max_recv_wr;    /* Requested max number of outstanding WRs in the RQ */
                   uint32_t                max_send_sge;   /* Requested max number of scatter/gather (s/g) elements in a WR in the SQ */
                   uint32_t                max_recv_sge;   /* Requested max number of s/g elements in a WR in the RQ */
                   uint32_t                max_inline_data;/* Requested max number of data (bytes) that can be posted inline to the SQ, otherwise 0 */
           };
    
           The function **ibv_create_qp()** will update the _qp_init_attr_ ->cap
           struct with the actual QP values of the QP that was created; the
           values will be greater than or equal to the values requested.
    
           **ibv_destroy_qp()** destroys the QP _qp_.
    


## RETURN VALUE



           **ibv_create_qp()** returns a pointer to the created QP, or NULL if
           the request fails.  Check the QP number (**qp_num**) in the returned
           QP.
    
           **ibv_destroy_qp()** returns 0 on success, or the value of errno on
           failure (which indicates the failure reason).
    


## NOTES



           **ibv_create_qp()** will fail if a it is asked to create QP of a type
           other than **IBV_QPT_RC** or **IBV_QPT_UD** associated with an SRQ.
    
           The attributes max_recv_wr and max_recv_sge are ignored by
           **ibv_create_qp()** if the QP is to be associated with an SRQ.
    
           **ibv_destroy_qp()** fails if the QP is attached to a multicast group.
    
           **IBV_QPT_DRIVER** does not represent a specific service and is used
           for vendor specific QP logic.
    


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