SDN学习之路——第三天

               +-------------------+
               |    ovs-vswitchd   |<-->ovsdb-server
               +-------------------+
               |      ofproto      |<-->OpenFlow controllers
               +--------+-+--------+
               | netdev | | ofproto|
               +--------+ |provider|
               | netdev | +--------+
               |provider|
               +--------+
  • ovs-vswitchd : ovs的主要userspace程序,它通过ipc通道将db中的配置下发到ofproto层,也会把状态和统计信息保存到db中

  • ofproto : Open vSwitch library,可以实现ovs交换机,它与controller通信,

  • netdev : 网路设备的抽象

                   _
                  |   +-------------------+
                  |   |    ovs-vswitchd   |<-->ovsdb-server
                  |   +-------------------+
                  |   |      ofproto      |<-->OpenFlow controllers
                  |   +--------+-+--------+  _
                  |   | netdev | |ofproto-|   | 
                  |   +--------+ |  dpif  |   |
                  |   | netdev | +--------+   |
                  |   |provider| |  dpif  |   |
       userspace  |   +---||---+ +--------+   |
                  |       ||     |  dpif  |   | implementation of
                  |       ||     |provider|   | ofproto provider
                  |_      ||     +---||---+   |
                          ||         ||       |
                   _  +---||-----+---||---+   |
                  |   |          |datapath|   |
           kernel |   |          +--------+  _|
                  |   |                   |
                  |_  +--------||---------+
                               ||
                            physical
                               NIC
    

netdev provider

"netdev provider"实现一个操作系统和具体的硬件端口,e.g. eth0 on Linux.
netdev_class是一个可以实现网络设备的接口类

struct netdev_class {
    /* Type of netdevs in this class, e.g. "system", "tap", "gre", etc.
     *
     * One of the providers should supply a "system" type, since this is
     * the type assumed if no type is specified when opening a netdev.
     * The "system" type corresponds to an existing network device on
     * the system. */
    const char *type;

    /* If 'true' then this netdev should be polled by PMD threads. */
    bool is_pmd;

/* ## ------------------- ## */
/* ## Top-Level Functions ## */
/* ## ------------------- ## */

    /* Called when the netdev provider is registered, typically at program
     * startup.  Returning an error from this function will prevent any network
     * device in this class from being opened.
     *
     * This function may be set to null if a network device class needs no
     * initialization at registration time. */
    int (*init)(void);

    /* Performs periodic work needed by netdevs of this class.  May be null if
     * no periodic work is necessary.
     *
     * 'netdev_class' points to the class.  It is useful in case the same
     * function is used to implement different classes. */
    void (*run)(const struct netdev_class *netdev_class);

    /* Arranges for poll_block() to wake up if the "run" member function needs
     * to be called.  Implementations are additionally required to wake
     * whenever something changes in any of its netdevs which would cause their
     * ->change_seq() function to change its result.  May be null if nothing is
     * needed here.
     *
     * 'netdev_class' points to the class.  It is useful in case the same
     * function is used to implement different classes. */
    void (*wait)(const struct netdev_class *netdev_class);

/* ## ---------------- ## */
/* ## netdev Functions ## */
/* ## ---------------- ## */
    struct netdev *(*alloc)(void);
    int (*construct)(struct netdev *);
    void (*destruct)(struct netdev *);
    void (*dealloc)(struct netdev *);
    int (*get_config)(const struct netdev *netdev, struct smap *args);

    /* Changes the device 'netdev''s configuration to 'args'.
    int (*set_config)(struct netdev *netdev, const struct smap *args,
                      char **errp);
    const struct netdev_tunnel_config *
        (*get_tunnel_config)(const struct netdev *netdev);
    int (*build_header)(const struct netdev *, struct ovs_action_push_tnl *data,
                        const struct netdev_tnl_build_header_params *params);
    void (*push_header)(const struct netdev *,
                        struct dp_packet *packet,
                        const struct ovs_action_push_tnl *data);
    struct dp_packet * (*pop_header)(struct dp_packet *packet);
    int (*get_numa_id)(const struct netdev *netdev);
    int (*set_tx_multiq)(struct netdev *netdev, unsigned int n_txq);
    int (*send)(struct netdev *netdev, int qid, struct dp_packet_batch *batch,
                bool concurrent_txq);
    void (*send_wait)(struct netdev *netdev, int qid);
    int (*set_etheraddr)(struct netdev *netdev, const struct eth_addr mac);
    int (*get_etheraddr)(const struct netdev *netdev, struct eth_addr *mac);
    int (*get_mtu)(const struct netdev *netdev, int *mtup);
    int (*set_mtu)(struct netdev *netdev, int mtu);
    int (*get_ifindex)(const struct netdev *netdev);
    int (*get_carrier)(const struct netdev *netdev, bool *carrier);
    long long int (*get_carrier_resets)(const struct netdev *netdev);
    int (*set_miimon_interval)(struct netdev *netdev, long long int interval);
    int (*get_stats)(const struct netdev *netdev, struct netdev_stats *);
    int (*get_custom_stats)(const struct netdev *netdev,
                            struct netdev_custom_stats *custom_stats);
    int (*get_features)(const struct netdev *netdev,
                        enum netdev_features *current,
                        enum netdev_features *advertised,
                        enum netdev_features *supported,
                        enum netdev_features *peer);
    int (*set_advertisements)(struct netdev *netdev,
                              enum netdev_features advertise);
    enum netdev_pt_mode (*get_pt_mode)(const struct netdev *netdev);
    int (*set_policing)(struct netdev *netdev, unsigned int kbits_rate,
                        unsigned int kbits_burst);
    int (*get_qos_types)(const struct netdev *netdev, struct sset *types);
    int (*get_qos_capabilities)(const struct netdev *netdev,
                                const char *type,
                                struct netdev_qos_capabilities *caps);
    int (*get_qos)(const struct netdev *netdev,
                   const char **typep, struct smap *details);
    int (*set_qos)(struct netdev *netdev,
                   const char *type, const struct smap *details);
    int (*get_queue)(const struct netdev *netdev,
                     unsigned int queue_id, struct smap *details);
    int (*set_queue)(struct netdev *netdev,
                     unsigned int queue_id, const struct smap *details);
    int (*delete_queue)(struct netdev *netdev, unsigned int queue_id);
    int (*get_queue_stats)(const struct netdev *netdev, unsigned int queue_id,
                           struct netdev_queue_stats *stats);
    int (*queue_dump_start)(const struct netdev *netdev, void **statep);
    int (*queue_dump_next)(const struct netdev *netdev, void *state,
                           unsigned int *queue_id, struct smap *details);
    int (*queue_dump_done)(const struct netdev *netdev, void *state);
    int (*dump_queue_stats)(const struct netdev *netdev,
                            void (*cb)(unsigned int queue_id,
                                       struct netdev_queue_stats *,
                                       void *aux),
                            void *aux);
    int (*set_in4)(struct netdev *netdev, struct in_addr addr,
                   struct in_addr mask);
    int (*get_addr_list)(const struct netdev *netdev, struct in6_addr **in,
                         struct in6_addr **mask, int *n_in6);
    int (*add_router)(struct netdev *netdev, struct in_addr router);
    int (*get_next_hop)(const struct in_addr *host, struct in_addr *next_hop,
                        char **netdev_name);
    int (*get_status)(const struct netdev *netdev, struct smap *smap);
    int (*arp_lookup)(const struct netdev *netdev, ovs_be32 ip,
                      struct eth_addr *mac);
    int (*update_flags)(struct netdev *netdev, enum netdev_flags off,
                        enum netdev_flags on, enum netdev_flags *old_flags);
    int (*reconfigure)(struct netdev *netdev);
/* ## -------------------- ## */
/* ## netdev_rxq Functions ## */
/* ## -------------------- ## */
    struct netdev_rxq *(*rxq_alloc)(void);
    int (*rxq_construct)(struct netdev_rxq *);
    void (*rxq_destruct)(struct netdev_rxq *);
    void (*rxq_dealloc)(struct netdev_rxq *);
    int (*rxq_recv)(struct netdev_rxq *rx, struct dp_packet_batch *batch,
                    int *qfill);
    void (*rxq_wait)(struct netdev_rxq *rx);
    /* Discards all packets waiting to be received from 'rx'. */
    int (*rxq_drain)(struct netdev_rxq *rx);

    /* ## -------------------------------- ## */
    /* ## netdev flow offloading functions ## */
    /* ## -------------------------------- ## */
    int (*flow_flush)(struct netdev *);
    int (*flow_dump_create)(struct netdev *, struct netdev_flow_dump **dump);
    int (*flow_dump_destroy)(struct netdev_flow_dump *);
    bool (*flow_dump_next)(struct netdev_flow_dump *, struct match *,
                           struct nlattr **actions,
                           struct dpif_flow_stats *stats,
                           struct dpif_flow_attrs *attrs, ovs_u128 *ufid,
                           struct ofpbuf *rbuffer, struct ofpbuf *wbuffer);
    int (*flow_put)(struct netdev *, struct match *, struct nlattr *actions,
                    size_t actions_len, const ovs_u128 *ufid,
                    struct offload_info *info, struct dpif_flow_stats *);
    int (*flow_get)(struct netdev *, struct match *, struct nlattr **actions,
                    const ovs_u128 *ufid, struct dpif_flow_stats *,
                    struct dpif_flow_attrs *, struct ofpbuf *wbuffer);
    int (*flow_del)(struct netdev *, const ovs_u128 *ufid,
                    struct dpif_flow_stats *);
    int (*init_flow_api)(struct netdev *);
    uint32_t (*get_block_id)(struct netdev *);
};

ovs已经实现的网络设备有多种,netdev-linux.c、netdev_vport.c、netdev-dummy.c等,具体讲一下netdev_vport,对于任意的net_device设备,当把设备连接到br上时(即add port),需要把OVS的接收函数hook到net_device的包接收函数中,这样net_device的进包就不会进入常规的内核协议栈中,而是由OVS接过来处理,实现如下:
netdev_create

static struct vport *netdev_create(const struct vport_parms *parms)
{
	struct vport *vport;

	vport = ovs_vport_alloc(0, &ovs_netdev_vport_ops, parms);
	if (IS_ERR(vport))
		return vport;

	return ovs_netdev_link(vport, parms->name);
}

ovs_netdev_link

struct vport *ovs_netdev_link(struct vport *vport, const char *name)
{
	int err;

	vport->dev = dev_get_by_name(ovs_dp_get_net(vport->dp), name);
	if (!vport->dev) {
		err = -ENODEV;
		goto error_free_vport;
	}
// 判断如果是internal或者不是Ether或者是回环,则直接丢弃
	if (vport->dev->flags & IFF_LOOPBACK ||
	    (vport->dev->type != ARPHRD_ETHER &&
	     vport->dev->type != ARPHRD_NONE) ||
	    ovs_is_internal_dev(vport->dev)) {
		err = -EINVAL;
		goto error_put;
	}

	rtnl_lock();
	err = netdev_master_upper_dev_link(vport->dev,
					   get_dpdev(vport->dp),
					   NULL, NULL, NULL);
	if (err)
		goto error_unlock;

	err = netdev_rx_handler_register(vport->dev, netdev_frame_hook,
					 vport);
	if (err)
		goto error_master_upper_dev_unlink;

	dev_disable_lro(vport->dev);
	dev_set_promiscuity(vport->dev, 1);
	vport->dev->priv_flags |= IFF_OVS_DATAPATH;
	rtnl_unlock();

	return vport;

error_master_upper_dev_unlink:
	netdev_upper_dev_unlink(vport->dev, get_dpdev(vport->dp));
error_unlock:
	rtnl_unlock();
error_put:
	dev_put(vport->dev);
error_free_vport:
	ovs_vport_free(vport);
	return ERR_PTR(err);
}

通过netdev_rx_handler_register将vport与dev连接在一起,dev存储在vport的priv数据中,netdev_frame_hook实际上是调用了netdev_port_receive,netdev_port_receive接着又调用了osv_vport_receive,之后的过程就是我们所熟悉的了。

ofproto Providers

ofproto_class定义了ofproto Provider实现的一个接口,具体实现为ofproto_dpif_class,除了ofproto_class,还有几个重要的代表不同组成部分的数据结构,如struct ofport,rule,oftable,ofgroup等。
ofproto_class

struct ofproto_class {
    
    void (*init)(const struct shash *iface_hints);
    void (*enumerate_types)(struct sset *types);
    int (*enumerate_names)(const char *type, struct sset *names);
    int (*del)(const char *type, const char *name);
    const char *(*port_open_type)(const char *datapath_type,
                                  const char *port_type);
    int (*type_run)(const char *type);
    void (*type_wait)(const char *type);
    struct ofproto *(*alloc)(void);
    int (*construct)(struct ofproto *ofproto);
    void (*destruct)(struct ofproto *ofproto, bool del);
    void (*dealloc)(struct ofproto *ofproto);
    int (*run)(struct ofproto *ofproto);
    void (*wait)(struct ofproto *ofproto);
    void (*get_memory_usage)(const struct ofproto *ofproto,
                             struct simap *usage);
    void (*type_get_memory_usage)(const char *type, struct simap *usage);
    void (*flush)(struct ofproto *ofproto);
    void (*query_tables)(struct ofproto *ofproto,
                         struct ofputil_table_features *features,
                         struct ofputil_table_stats *stats);
    void (*set_tables_version)(struct ofproto *ofproto, ovs_version_t version);
    struct ofport *(*port_alloc)(void);
    int (*port_construct)(struct ofport *ofport);
    void (*port_destruct)(struct ofport *ofport, bool del);
    void (*port_dealloc)(struct ofport *ofport);
    void (*port_modified)(struct ofport *ofport);
    int (*port_query_by_name)(const struct ofproto *ofproto,
                              const char *devname, struct ofproto_port *port);
    int (*port_add)(struct ofproto *ofproto, struct netdev *netdev);
    int (*port_del)(struct ofproto *ofproto, ofp_port_t ofp_port);
    int (*port_set_config)(const struct ofport *port, const struct smap *cfg);
    /* Get port stats */
    int (*port_get_stats)(const struct ofport *port,
                          struct netdev_stats *stats);
    int (*port_dump_start)(const struct ofproto *ofproto, void **statep);
    int (*port_dump_next)(const struct ofproto *ofproto, void *state,
                          struct ofproto_port *port);
    int (*port_dump_done)(const struct ofproto *ofproto, void *state);
    int (*port_poll)(const struct ofproto *ofproto, char **devnamep);
    void (*port_poll_wait)(const struct ofproto *ofproto);
    int (*port_is_lacp_current)(const struct ofport *port);
    int (*port_get_lacp_stats)(const struct ofport *port,
                               struct lacp_slave_stats *stats);
    enum ofperr (*rule_choose_table)(const struct ofproto *ofproto,
                                     const struct minimatch *match,
                                     uint8_t *table_idp);
    
    /* Rules indexed on their cookie values, in all flow tables. */
    struct rule *(*rule_alloc)(void);
    enum ofperr (*rule_construct)(struct rule *rule)
        /* OVS_REQUIRES(ofproto_mutex) */;
    void (*rule_insert)(struct rule *rule, struct rule *old_rule,
                        bool forward_counts)
        /* OVS_REQUIRES(ofproto_mutex) */;
    void (*rule_delete)(struct rule *rule) /* OVS_REQUIRES(ofproto_mutex) */;
    void (*rule_destruct)(struct rule *rule);
    void (*rule_dealloc)(struct rule *rule);
    /* ## ------------------------- ## */
    /* ## OFPP_NORMAL configuration ## */
    /* ## ------------------------- ## */

    /* Configures NetFlow on 'ofproto' according to the options in
     * 'netflow_options', or turns off NetFlow if 'netflow_options' is NULL.
     *
     * EOPNOTSUPP as a return value indicates that 'ofproto' does not support
     * NetFlow, as does a null pointer. */
    int (*set_netflow)(struct ofproto *ofproto,
                       const struct netflow_options *netflow_options);

    void (*get_netflow_ids)(const struct ofproto *ofproto,
                            uint8_t *engine_type, uint8_t *engine_id);

    /* Configures sFlow on 'ofproto' according to the options in
     * 'sflow_options', or turns off sFlow if 'sflow_options' is NULL.
     *
     * EOPNOTSUPP as a return value indicates that 'ofproto' does not support
     * sFlow, as does a null pointer. */
    int (*set_sflow)(struct ofproto *ofproto,
                     const struct ofproto_sflow_options *sflow_options);

    /* Configures IPFIX on 'ofproto' according to the options in
     * 'bridge_exporter_options' and the 'flow_exporters_options'
     * array, or turns off IPFIX if 'bridge_exporter_options' and
     * 'flow_exporters_options' is NULL.
     *
     * EOPNOTSUPP as a return value indicates that 'ofproto' does not support
     * IPFIX, as does a null pointer. */
    int (*set_ipfix)(
        struct ofproto *ofproto,
        const struct ofproto_ipfix_bridge_exporter_options
            *bridge_exporter_options,
        const struct ofproto_ipfix_flow_exporter_options
            *flow_exporters_options, size_t n_flow_exporters_options);

    /* Gets IPFIX stats on 'ofproto' according to the exporter of birdge
     * IPFIX or flow-based IPFIX.
     *
     * OFPERR_NXST_NOT_CONFIGURED as a return value indicates that bridge
     * IPFIX or flow-based IPFIX is not configured. */

dpif provider

ofproto_dpif是内置的ofproto provider,datapath尝试匹配收到的数据包,如果匹配成功,则执行action;否则则将数据包传给dpif(dpif将自己的大部分功能下放给dpif provider),dpif尝试进行full flow table lookup,如果找到,则执行action;否则,则把数据报传送给controller。
dpif class是datapath interface实现的工厂接口类,用于和实际的datapath, e.g. openvswitch.ko, 或者userspace datapath交互。目前已有的两个dpif的实现是dpif-netlink和dpif-netdev,前者是基于内核datapath的dpif实现,后者基于用户态datapath,具体定义如下:
dpif_netdev_class

const struct dpif_class dpif_netdev_class = {
    "netdev",
    dpif_netdev_init,
    dpif_netdev_enumerate,
    dpif_netdev_port_open_type,
    dpif_netdev_open,
    dpif_netdev_close,
    dpif_netdev_destroy,
    dpif_netdev_run,
    dpif_netdev_wait,
    dpif_netdev_get_stats,
    dpif_netdev_port_add,
    dpif_netdev_port_del,
    dpif_netdev_port_set_config,
    dpif_netdev_port_query_by_number,
    dpif_netdev_port_query_by_name,
    NULL,                       /* port_get_pid */
    dpif_netdev_port_dump_start,
    dpif_netdev_port_dump_next,
    dpif_netdev_port_dump_done,
    dpif_netdev_port_poll,
    dpif_netdev_port_poll_wait,
    dpif_netdev_flow_flush,
    dpif_netdev_flow_dump_create,
    dpif_netdev_flow_dump_destroy,
    dpif_netdev_flow_dump_thread_create,
    dpif_netdev_flow_dump_thread_destroy,
    dpif_netdev_flow_dump_next,
    dpif_netdev_operate,
    NULL,                       /* recv_set */
    NULL,                       /* handlers_set */
    dpif_netdev_set_config,
    dpif_netdev_queue_to_priority,
    NULL,                       /* recv */
    NULL,                       /* recv_wait */
    NULL,                       /* recv_purge */
    dpif_netdev_register_dp_purge_cb,
    dpif_netdev_register_upcall_cb,
    dpif_netdev_enable_upcall,
    dpif_netdev_disable_upcall,
    dpif_netdev_get_datapath_version,
    dpif_netdev_ct_dump_start,
    dpif_netdev_ct_dump_next,
    dpif_netdev_ct_dump_done,
    dpif_netdev_ct_flush,
    dpif_netdev_ct_set_maxconns,
    dpif_netdev_ct_get_maxconns,
    dpif_netdev_ct_get_nconns,
    NULL,                       /* ct_set_limits */
    NULL,                       /* ct_get_limits */
    NULL,                       /* ct_del_limits */
    dpif_netdev_meter_get_features,
    dpif_netdev_meter_set,
    dpif_netdev_meter_get,
    dpif_netdev_meter_del,
};

dpif_netlink_class

const struct dpif_class dpif_netlink_class = {
    "system",
    NULL,                       /* init */
    dpif_netlink_enumerate,
    NULL,
    dpif_netlink_open,
    dpif_netlink_close,
    dpif_netlink_destroy,
    dpif_netlink_run,
    NULL,                       /* wait */
    dpif_netlink_get_stats,
    dpif_netlink_port_add,
    dpif_netlink_port_del,
    NULL,                       /* port_set_config */
    dpif_netlink_port_query_by_number,
    dpif_netlink_port_query_by_name,
    dpif_netlink_port_get_pid,
    dpif_netlink_port_dump_start,
    dpif_netlink_port_dump_next,
    dpif_netlink_port_dump_done,
    dpif_netlink_port_poll,
    dpif_netlink_port_poll_wait,
    dpif_netlink_flow_flush,
    dpif_netlink_flow_dump_create,
    dpif_netlink_flow_dump_destroy,
    dpif_netlink_flow_dump_thread_create,
    dpif_netlink_flow_dump_thread_destroy,
    dpif_netlink_flow_dump_next,
    dpif_netlink_operate,
    dpif_netlink_recv_set,
    dpif_netlink_handlers_set,
    NULL,                       /* set_config */
    dpif_netlink_queue_to_priority,
    dpif_netlink_recv,
    dpif_netlink_recv_wait,
    dpif_netlink_recv_purge,
    NULL,                       /* register_dp_purge_cb */
    NULL,                       /* register_upcall_cb */
    NULL,                       /* enable_upcall */
    NULL,                       /* disable_upcall */
    dpif_netlink_get_datapath_version, /* get_datapath_version */
    dpif_netlink_ct_dump_start,
    dpif_netlink_ct_dump_next,
    dpif_netlink_ct_dump_done,
    dpif_netlink_ct_flush,
    NULL,                       /* ct_set_maxconns */
    NULL,                       /* ct_get_maxconns */
    NULL,                       /* ct_get_nconns */
    dpif_netlink_ct_set_limits,
    dpif_netlink_ct_get_limits,
    dpif_netlink_ct_del_limits,
    dpif_netlink_meter_get_features,
    dpif_netlink_meter_set,
    dpif_netlink_meter_get,
    dpif_netlink_meter_del,
};

ofproto_dpif_class

const struct ofproto_class ofproto_dpif_class = {
    init,
    enumerate_types,
    enumerate_names,
    del,
    port_open_type,
    type_run,
    type_wait,
    alloc,
    construct,
    destruct,
    dealloc,
    run,
    ofproto_dpif_wait,
    NULL,                       /* get_memory_usage. */
    type_get_memory_usage,
    flush,
    query_tables,
    set_tables_version,
    port_alloc,
    port_construct,
    port_destruct,
    port_dealloc,
    port_modified,
    port_reconfigured,
    port_query_by_name,
    port_add,
    port_del,
    port_set_config,
    port_get_stats,
    port_dump_start,
    port_dump_next,
    port_dump_done,
    port_poll,
    port_poll_wait,
    port_is_lacp_current,
    port_get_lacp_stats,
    NULL,                       /* rule_choose_table */
    rule_alloc,
    rule_construct,
    rule_insert,
    NULL,                       /* rule_delete */
    rule_destruct,
    rule_dealloc,
    rule_get_stats,
    packet_xlate,
    packet_xlate_revert,
    packet_execute,
    set_frag_handling,
    nxt_resume,
    set_netflow,
    get_netflow_ids,
    set_sflow,
    set_ipfix,
    get_ipfix_stats,
    set_cfm,
    cfm_status_changed,
    get_cfm_status,
    set_lldp,
    get_lldp_status,
    set_aa,
    aa_mapping_set,
    aa_mapping_unset,
    aa_vlan_get_queued,
    aa_vlan_get_queue_size,
    set_bfd,
    bfd_status_changed,
    get_bfd_status,
    set_stp,
    get_stp_status,
    set_stp_port,
    get_stp_port_status,
    get_stp_port_stats,
    set_rstp,
    get_rstp_status,
    set_rstp_port,
    get_rstp_port_status,
    set_queues,
    bundle_set,
    bundle_remove,
    mirror_set__,
    mirror_get_stats__,
    set_flood_vlans,
    is_mirror_output_bundle,
    forward_bpdu_changed,
    set_mac_table_config,
    set_mcast_snooping,
    set_mcast_snooping_port,
    meter_get_features,
    meter_set,
    meter_get,
    meter_del,
    group_alloc,                /* group_alloc */
    group_construct,            /* group_construct */
    group_destruct,             /* group_destruct */
    group_dealloc,              /* group_dealloc */
    NULL,                       /* group_modify */
    group_get_stats,            /* group_get_stats */
    get_datapath_version,       /* get_datapath_version */
    type_set_config,
    ct_flush,                   /* ct_flush */
}; 

《How to Port Open vSwitch to New Software or Hardware》

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