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IBV_CREATE_QP_EX(3) Libibverbs Programmer's Manual IBV_CREATE_QP_EX(3)


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


#include <infiniband/verbs.h>

struct ibv_qp *ibv_create_qp_ex(struct ibv_context *context,
                                struct ibv_qp_init_attr_ex *qp_init_attr);

int ibv_destroy_qp(struct ibv_qp *qp);


ibv_create_qp_ex() creates a queue pair (QP) associated with the protection domain pd. The argument qp_init_attr_ex is an ibv_qp_init_attr_ex struct, as defined in <infiniband/verbs.h>.

struct ibv_qp_init_attr_ex {

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 or IBV_QPT_RAW_PACKET */ int sq_sig_all; /* If set, each Work Request (WR) submitted to the SQ generates a completion entry */ uint32_t comp_mask; /* Identifies valid fields */ struct ibv_pd *pd; /* PD to be associated with the QP */ struct ibv_xrcd *xrcd; /* XRC domain to be associated with the target QP */ enum ibv_qp_create_flags create_flags; /* Creation flags for this QP */ uint16_t max_tso_header; /* Maximum TSO header size */ struct ibv_rwq_ind_table *rwq_ind_tbl; /* Indirection table to be associated with the QP */ struct ibv_rx_hash_conf rx_hash_conf; /* RX hash configuration to be used */ uint32_t source_qpn; /* Source QP number, creation flag IBV_QP_CREATE_SOURCE_QPN should be set, few NOTEs below */
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 SQ */ uint32_t max_inline_data;/* Requested max number of data (bytes) that can be posted inline to the SQ, otherwise 0 */
enum ibv_qp_create_flags {
IBV_QP_CREATE_BLOCK_SELF_MCAST_LB = 1 << 1, /* Prevent self multicast loopback */ IBV_QP_CREATE_SCATTER_FCS = 1 << 8, /* FCS field will be scattered to host memory */ IBV_QP_CREATE_CVLAN_STRIPPING = 1 << 9, /* CVLAN field will be stripped from incoming packets */ IBV_QP_CREATE_SOURCE_QPN = 1 << 10, /* The created QP will use the source_qpn as its wire QP number */ IBV_QP_CREATE_PCI_WRITE_END_PADDING = 1 << 11, /* Incoming packets will be padded to cacheline size */
struct ibv_rx_hash_conf {
uint8_t rx_hash_function; /* RX hash function, use enum ibv_rx_hash_function_flags */ uint8_t rx_hash_key_len; /* RX hash key length */ uint8_t *rx_hash_key; /* RX hash key data */ uint64_t rx_hash_fields_mask; /* RX fields that should participate in the hashing, use enum ibv_rx_hash_fields */

enum ibv_rx_hash_fields {

IBV_RX_HASH_SRC_IPV4 = 1 << 0, IBV_RX_HASH_DST_IPV4 = 1 << 1, IBV_RX_HASH_SRC_IPV6 = 1 << 2, IBV_RX_HASH_DST_IPV6 = 1 << 3, IBV_RX_HASH_SRC_PORT_TCP = 1 << 4, IBV_RX_HASH_DST_PORT_TCP = 1 << 5, IBV_RX_HASH_SRC_PORT_UDP = 1 << 6, IBV_RX_HASH_DST_PORT_UDP = 1 << 7, /* When using tunneling protocol, e.g. VXLAN, then we have an inner (encapsulated packet) and outer. * For applying RSS on the inner packet, then the following field should be set with one of the L3/L4 fields. */ IBV_RX_HASH_INNER = (1UL << 31),

The function ibv_create_qp_ex() will update the qp_init_attr_ex->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.


ibv_create_qp_ex() 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).


The attributes max_recv_wr and max_recv_sge are ignored by ibv_create_qp_ex() if the QP is to be associated with an SRQ.

The attribute source_qpn is supported only on UD QP, without flow steering RX should not be possible.

ibv_destroy_qp() fails if the QP is attached to a multicast group.


ibv_alloc_pd(3), ibv_modify_qp(3), ibv_query_qp(3), ibv_create_rwq_ind_table(3)


Yishai Hadas <>
2013-06-26 libibverbs