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kvm console 的使用

news 2025/6/25 10:31:08

使用介绍：

[root@kvm1 ~]# virsh console --helpNAME控制台 - 连接到客户机控制台SYNOPSISconsole <domain> [--devname <string>] [--force] [--safe]DESCRIPTION为虚拟机连接虚拟串行控制台OPTIONS[--domain] <string>  domain name, id or uuid--devname <string>  字符设备名称--force          	强制连接控制台（断开已连接的会话）--safe           	只有在具备安全操作控制台的相关支持的情况下，才可进行连接。

使用一台新安装的虚拟机测试

无法进入到虚拟机的控制台；原因是：虚拟机没有正确配置串口设备

[root@kvm1 ~]# virsh listId   Name        State
---------------------------3    centos7.9   running
。/
[root@kvm1 ~]# virsh console centos7.9
Connected to domain centos7.9
Escape character is ^]

为已经安装好的虚拟机配置串口

我的虚拟机是centos7.9 ，也测试过ubuntu22.04步骤也是一样的；这里必须能够进入到虚拟机，使用ip连接到虚拟机或者使用virt-manger

在内核启动参数中添加 console=ttyS0 参数，添加完重启系统

grubby --update-kernel=ALL --args="console=ttyS0"

启动getty 程序

# systemd 会在 ttyS0 端口上启动 getty 程序。getty 程序会监听该端口，等待用户输入用户名和密码。
[root@localhost ~]# systemctl start serial-getty@ttyS0
[root@localhost ~]# systemctl enbale serial-getty@ttyS0[root@localhost ~]# systemctl status serial-getty@ttyS0
● serial-getty@ttyS0.service - Serial Getty on ttyS0Loaded: loaded (/usr/lib/systemd/system/serial-getty@.service; enabled; vendor preset: disabled)Active: active (running) since Tue 2025-06-24 05:03:42 EDT; 1min 12s agoDocs: man:agetty(8)man:systemd-getty-generator(8)http://0pointer.de/blog/projects/serial-console.htmlMain PID: 8627 (agetty)CGroup: /system.slice/system-serial\x2dgetty.slice/serial-getty@ttyS0.service└─8627 /sbin/agetty --keep-baud 115200,38400,9600 ttyS0 vt220Jun 24 05:03:42 localhost.localdomain systemd[1]: serial-getty@ttyS0.service holdoff time over, scheduling restart.
Jun 24 05:03:42 localhost.localdomain systemd[1]: Stopped Serial Getty on ttyS0.
Jun 24 05:03:42 localhost.localdomain systemd[1]: Started Serial Getty on ttyS0.

使用宿主机来连接虚拟机

virsh console centos7.9 敲一下回车进入输入账号密码界面，使用 ctrl + ] 退出虚拟机

[root@kvm1 ~]# virsh listId   Name        State
---------------------------3    centos7.9   running[root@kvm1 ~]# virsh console centos7.9
Connected to domain centos7.9
Escape character is ^]CentOS Linux 7 (Core)
Kernel 3.10.0-1160.el7.x86_64 on an x86_64localhost login: root
Password:
Last login: Tue Jun 24 05:03:30 on ttyS0
[root@localhost ~]#
[root@kvm1 ~]#

在创建虚拟机时添加 console=ttyS0 内核参数

virt-install \--name centos7.9 \--os-type linux \--os-variant centos7.0 \--memory 2048 \--vcpus 1 \--disk size=20 \--location /var/lib/libvirt/images/CentOS-7-x86_64-DVD-2009.iso \--network bridge=br0,model=virtio \--initrd-inject /root/centos79.cfs \--extra-args="ks=file:/centos79.cfs console=ttyS0" \--graphics vnc \--noautoconsole

--extra-args="ks=file:/centos79.cfs console=ttyS0" ：添加内核参数，不但指定了ks文件，而且添加了串口

ks文件内容如下：

#version=DEVEL
# System authorization information
auth --enableshadow --passalgo=sha512
# Use CDROM installation media
cdrom
# Use graphical install
text
# Run the Setup Agent on first boot
firstboot --enable
ignoredisk --only-use=vda
# Keyboard layouts
keyboard --vckeymap=us --xlayouts='us'
# System language
lang en_US.UTF-8# Network information
network  --bootproto=dhcp --device=eth0 --ipv6=auto --no-activate
network  --hostname=localhost.localdomain# Root password
rootpw --iscrypted $6$6RNXJjFR0En6Sxwj$21fidwn6Mt1BPl9rMzJCg34DxtrEUHbjeWrirBAkyt45BC8HJsR6Cw0BJ5roT0U2QBAvucc23MEjA.NvTsues.
# System services
services --enabled="chronyd"
# System timezone
timezone America/New_York --isUtc
# System bootloader configuration
bootloader --append=" crashkernel=auto" --location=mbr --boot-drive=vda
# Partition clearing information
clearpart --all --initlabel
# Disk partitioning information
part /boot --fstype="xfs" --ondisk=vda --size=300
part / --fstype="xfs" --ondisk=vda --grow%packages
@^minimal
@core
chrony
kexec-tools%end%addon com_redhat_kdump --enable --reserve-mb='auto'%end%anaconda
pwpolicy root --minlen=6 --minquality=1 --notstrict --nochanges --notempty
pwpolicy user --minlen=6 --minquality=1 --notstrict --nochanges --emptyok
pwpolicy luks --minlen=6 --minquality=1 --notstrict --nochanges --notempty
%end
reboot

在宿主机上使用virsh consle 来连接虚拟机
可以看出是正常连接的.

[root@kvm1 ~]# virsh console centos7.9
Connected to domain centos7.9
Escape character is ^]CentOS Linux 7 (Core)
Kernel 3.10.0-1160.el7.x86_64 on an x86_64192 login: root
Password:
Last login: Tue Jun 24 09:57:02 from 192.168.25.1

查看getty 程序 是否启动，ttyS0 端口是否被监听

如下可以看出，在使用virsh-install 安装虚拟机时在内核 console=ttyS0，会自动启动getty 程序

[root@192 ~]# systemctl status serial-getty@ttyS0
● serial-getty@ttyS0.service - Serial Getty on ttyS0Loaded: loaded (/usr/lib/systemd/system/serial-getty@.service; disabled; vendor preset: disabled)Active: active (running) since Tue 2025-06-24 11:42:34 EDT; 1min 38s agoDocs: man:agetty(8)man:systemd-getty-generator(8)http://0pointer.de/blog/projects/serial-console.htmlMain PID: 565 (agetty)CGroup: /system.slice/system-serial\x2dgetty.slice/serial-getty@ttyS0.service└─565 /sbin/agetty --keep-baud 115200,38400,9600 ttyS0 vt220Jun 24 11:42:34 localhost.localdomain systemd[1]: Started Serial Getty on ttyS0.

查看内核参数

总结：启动串口需要在内核启动参数种添加 console=ttyS0，需要启动 serial-getty@ttyS0 ttyS0串口编号，补充：串口端口号必须在 /etc/securetty 里面。

[root@192 ~]#  cat /etc/grub2.cfg | grep "console=ttyS0"linux16 /vmlinuz-3.10.0-1160.el7.x86_64 root=UUID=237e423d-356b-4352-9bc0-19e1321b4d79 ro crashkernel=auto spectre_v2=retpoline console=ttyS0 LANG=en_US.UTF-8linux16 /vmlinuz-0-rescue-1d166deb1edb4402b9b9267d1f2fee03 root=UUID=237e423d-356b-4352-9bc0-19e1321b4d79 ro crashkernel=auto spectre_v2=retpoline console=ttyS0