逻辑端口状态。它可以是下列枚举值之一：

• IBV_PORT_NOP - 保留值, 不应该出现
• IBV_PORT_DOWN - 逻辑链接已断开。端口的物理链路未up。在这种状态下，链路层将丢弃递送给它的所有数据包。

• IBV_PORT_INIT - 逻辑链接正在初始化。端口的物理链路已建立，但SM尚未配置逻辑链路。在这种状态下，链路层只能接收和发送SMP和流控制链路数据包，递交给它的其他类型的数据包将被丢弃

• IBV_PORT_ARMED - 逻辑链接已布防（Logical link is Armed）。端口的物理链路已建立，但SM尚未完全配置逻辑链路。在这种状态下，链路层可以接收和发送SMP和流控制链路数据包，可以接收其他类型的数据包，但是会丢弃非SMP数据包以进行发送。（but discards non SMP packets for sending）
• IBV_PORT_ACTIVE - 逻辑链接是活动的。链路层可以发送和接收所有数据包类型
• IBV_PORT_ACTIVE_DEFER - 逻辑链接处于“活动延迟”状态。逻辑链接为活动，但物理链接出现故障。如果错误在超时之前恢复，则逻辑链接将返回到IBV_PORT_ACTIVE，否则它将移动到IBV_PORT_DOWN

（If the error will be recovered within a timeout, the logical link will return to IBV_PORT_ACTIVE, otherwise it will move to IBV_PORT_DOWN）

该端口支持的最大MTU。它可以是下列枚举值之一：

• IBV_MTU_256 - MTU is 256 bytes
• IBV_MTU_512 - MTU is 512 bytes
• IBV_MTU_1024 - MTU is 1024 bytes
• IBV_MTU_2048 - MTU is 2048 bytes
• IBV_MTU_4096 - MTU is 4096 bytes

Active maximum MTU enabled on this port to transmit and receive. It can be one of the following enumerated values which specified for max_mtu. This value specify the maximum message size that can be configured in UC/RC QPs and the maximum message size that an UD QP can transmit

在此端口上启用的最大活动MTU进行发送和接收。它可以是为max_mtu指定的以下枚举值之一。此值指定可以在UC / RC QP中配置的最大消息大小以及UD QP可以传输的最大消息大小

• 1 << 1   - Indication that the SM that manages the subnet sending the packets from this port
• 1 << 10 - Indication that there is an SM which isn't active in this port
• 1 << 17 - Indication that an SNMP Tunneling agent is listening on this port
• 1 << 19 - Indication that a Device Management agent is listening on this port
• 1 << 20 - Indication that a Vendor specific agent is listening on this port
• 1 << 25 - Indication that this port capable of generating the IBV_EVENT_CLIENT_REREGISTER asynchronous event

• 1 - 1 VL: VL0
• 2 - 2 VLs: VL0, VL1
• 3 - 4 VLs: VL0 - VL3
• 4 - 8 VLs: VL0 - VL7
• 5 - 15 VLs: VL0 - VL14

• 1 - 1x
• 2 - 4x
• 4 - 8x
• 8 - 12x

• 1 - 2.5 Gbps
• 2 - 5.0 Gbps
• 4 - 10.0 Gbps
• 8 - 10.0 Gbps
• 16 - 14.0 Gbps
• 32 - 25.0 Gbps

• 1 - Sleep: The port drives its output to quiescent levels and does not respond to received data. In this state, the link is deactivated  without powering off the port
• 2 - Polling: The port transmits training sequences and responds to receive training sequences.
• 3 - Disabled: The port drives its output to quiescent levels and does not respond to receive data
• 4 - PortConfigurationTraining: Both transmitter and receive active and the port is attempting to configure and transition to the LinkUp state
• 5 - LinkUp: The port is available to send and receive packets
• 6 - LinkErrorRecovery: Port attempts to re-synchronize the link and return it to normal operation
• 7 - Phytest: Port allows the transmitter and received circuitry to be tested by external test equipment for compliance with the transmitter and receiver specifications

• IBV_LINK_LAYER_UNSPECIFIED - Legacy value, used to indicate that the link layer protocol is InfiniBand
• IBV_LINK_LAYER_INFINIBAND - Link layer protocol is InfiniBand
• IBV_LINK_LAYER_ETHERNET - Link layer protocol is Ethernet, thus IBoE (or RoCE) can be used

struct ibv_port_attr port_attr;
int port_num = 1;
 
rc = ibv_query_port(ctx, port_num, &port_attr);
if (rc) {
	fprintf(stderr, "Error, failed to query port %d attributes in device '%s'\n",
		port_num, ibv_get_device_name(ctx->device));
	return -1;
}