---
name: "ibv_query_port"
section: "3"
platform: "freebsd"
package: "base"
version: "16.0-CURRENT-20261027-61c70dc16a79"
release: "FreeBSD 16.0-CURRENT (2026-10-27)"
platforms: ["linux", "freebsd"]
url: "https://new.carta.tech/ibv_query_port"
---

# ibv\_query\_port(3)

query an RDMA port's attributes

## NAME

ibv\_query\_port - query an RDMA port's attributes

## SYNOPSIS

```
#include <infiniband/verbs.h>

int ibv_query_port(struct ibv_context *context, uint8_t port_num,
                   struct ibv_port_attr *port_attr);
```

## DESCRIPTION

**ibv\_query\_port()** returns the attributes of port *port\_num* for device context *context* through the pointer *port\_attr.* The argument *port\_attr* is an ibv\_port\_attr struct, as defined in \<infiniband/verbs.h\>.

```
struct ibv_port_attr {
enum ibv_port_state     state;          /* Logical port state */
enum ibv_mtu            max_mtu;        /* Max MTU supported by port */
enum ibv_mtu            active_mtu;     /* Actual MTU */
int                     gid_tbl_len;    /* Length of source GID table */
uint32_t                port_cap_flags; /* Port capabilities */
uint32_t                max_msg_sz;     /* Maximum message size */
uint32_t                bad_pkey_cntr;  /* Bad P_Key counter */
uint32_t                qkey_viol_cntr; /* Q_Key violation counter */
uint16_t                pkey_tbl_len;   /* Length of partition table */
uint16_t                lid;            /* Base port LID */
uint16_t                sm_lid;         /* SM LID */
uint8_t                 lmc;            /* LMC of LID */
uint8_t                 max_vl_num;     /* Maximum number of VLs */
uint8_t                 sm_sl;          /* SM service level */
uint8_t                 subnet_timeout; /* Subnet propagation delay */
uint8_t                 init_type_reply;/* Type of initialization performed by SM */
uint8_t                 active_width;   /* Currently active link width */
uint8_t                 active_speed;   /* Currently active link speed */
uint8_t                 phys_state;     /* Physical port state */
uint8_t                 link_layer;     /* link layer protocol of the port */
};

possible values for the link layer field are IBV_LINK_LAYER_INFINIBAND,
IBV_LINK_LAYER_ETHERNET, or IBV_LINK_LAYER_UNSPECIFIED.

```

## RETURN VALUE

**ibv\_query\_port()** returns 0 on success, or the value of errno on failure (which indicates the failure reason).

## SEE ALSO

[**ibv\_create\_qp**(3)](/ibv_create_qp/3.md), [**ibv\_destroy\_qp**(3)](/ibv_destroy_qp/3.md), [**ibv\_query\_qp**(3)](/ibv_query_qp/3.md), [**ibv\_create\_ah**(3)](/ibv_create_ah/3.md)

## AUTHORS

- Dotan Barak \<dotanba@gmail.com\>