运行 Ubuntu 16.04，默认情况下，virbr0 接口不会在启动时启动，这意味着我必须使用以下命令手动启动它：
$ sudo virsh net-start default
这也许不是什么大问题，而且我知道如何解决这个问题，但是以下命令的输出表明 virbr0 已配置为自动启动：
$ virsh net-list --all
Name State Autostart Persistent
----------------------------------------------------------
default active yes yes
有人能指点下一步该看哪里来帮助调试吗？
更新：
启动后在 /var/log/syslog 中看到的一些选定的行对我没有帮助，但可能对某些人有意义：
systemd-udevd[368]: Could not generate persistent MAC address for virbr0: No such file or directory
NetworkManager[862]: <info> [1508409794.6955] device added (path: /sys/devices/virtual/net/virbr0, iface: virbr0): no ifupdown configuration found.
NetworkManager[862]: <info> [1508409794.6956] device added (path: /sys/devices/virtual/net/virbr0-nic, iface: virbr0-nic): no ifupdown configuration found.
NetworkManager[862]: <info> [1508409794.7711] device (virbr0-nic): state change: unmanaged -> unavailable (reason 'connection-assumed') [10 20 41]
NetworkManager[862]: <info> [1508409794.7725] device (virbr0-nic): state change: unavailable -> disconnected (reason 'none') [20 30 0]
NetworkManager[862]: <info> [1508409796.0723] device (virbr0): state change: unmanaged -> unavailable (reason 'connection-assumed') [10 20 41]
avahi-daemon[847]: Registering new address record for 192.168.122.1 on virbr0.IPv4.
NetworkManager[862]: <info> [1508409796.0734] device (virbr0): state change: unavailable -> disconnected (reason 'connection-assumed') [20 30 41]
NetworkManager[862]: <info> [1508409796.0739] device (virbr0): Activation: starting connection 'virbr0' (6a02deba-6a45-44f3-8c7d-92bb6f8c287b)
. . .
NetworkManager[862]: <info> [1508409796.0829] device (virbr0): Activation: successful, device activated.
NetworkManager[862]: <info> [1508409796.0833] device (virbr0-nic): state change: secondaries -> activated (reason 'none') [90 100 0]
nm-dispatcher: req:5 'up' [virbr0]: new request (2 scripts)
nm-dispatcher: req:5 'up' [virbr0]: start running ordered scripts...
NetworkManager[862]: <info> [1508409796.0877] device (virbr0-nic): Activation: successful, device activated.
nm-dispatcher: req:6 'up' [virbr0-nic]: new request (2 scripts)
nm-dispatcher: req:6 'up' [virbr0-nic]: start running ordered scripts...
avahi-daemon[847]: Interface virbr0.IPv4 no longer relevant for mDNS.
avahi-daemon[847]: Leaving mDNS multicast group on interface virbr0.IPv4 with address 192.168.122.1.
kernel: [ 11.827450] virbr0: port 1(virbr0-nic) entered disabled state
NetworkManager[862]: <info> [1508409796.4151] device (virbr0): state change: activated -> unmanaged (reason 'connection-assumed') [100 10 41]
avahi-daemon[847]: Withdrawing address record for 192.168.122.1 on virbr0.
nm-dispatcher: req:7 'down' [virbr0]: new request (2 scripts)
nm-dispatcher: req:7 'down' [virbr0]: start running ordered scripts...
kernel: [ 13.245387] device virbr0-nic left promiscuous mode
kernel: [ 13.245390] virbr0: port 1(virbr0-nic) entered disabled state
NetworkManager[862]: <info> [1508409797.8565] device (virbr0-nic): state change: activated -> unmanaged (reason 'unmanaged') [100 10 3]
NetworkManager[862]: <info> [1508409797.8565] device (virbr0): bridge port virbr0-nic was detached
NetworkManager[862]: <info> [1508409797.8566] device (virbr0-nic): released from master device virbr0
NetworkManager[862]: <info> [1508409797.8620] devices removed (path: /sys/devices/virtual/net/virbr0-nic, iface: virbr0-nic)
nm-dispatcher: req:8 'down' [virbr0-nic]: new request (2 scripts)
nm-dispatcher: req:8 'down' [virbr0-nic]: start running ordered scripts...
NetworkManager[862]: <info> [1508409797.8990] devices removed (path: /sys/devices/virtual/net/virbr0, iface: virbr0)
看起来有点像 virbr0 在启动期间被启用然后再次被禁用。
答案1
libvirtd如果网络标记为自动启动，则它应该在启动时立即启动。因此请检查是否libvirtd.service设置为在启动时自动启动。
另外，在您的第二条virsh命令中，您省略了sudo，因此有可能/很可能您正在连接到不同的libvirtd实例 - 以您的用户帐户运行的实例，而不是特权实例libvirtd。因此，请务必尝试sudo virsh net-list --all，如果没有显示自动启动，则运行sudo virsh net-autostart default
答案2
根据我的经验，libvirt 不会在启动时启动，您需要手动启动它。或者您需要创建一个脚本以通过 systemctl 在启动时启动 libvirt