centos8 kvm启用 virsh console

新建一个centos8的虚拟机，使用virsh console 虚拟机连接失败，查阅一通资料后发现了解决方法

其中ttyS0中的S代表Serial Port Terminal，所以这是一个是虚拟串口，联系起来看就好理解许多，通过console使用串口登陆设备，前提是得有这么一个串口

虚拟机中执行以下命令：

grubby --update-kernel=ALL --args="console=ttyS0"  && init 6

然后，物理机中执行以下命令：

virsh list --all
virsh console 虚拟机

# 阿里云主机的grub文件参考

]# cat /etc/default/grub
GRUB_TIMEOUT=1
GRUB_DISTRIBUTOR="$(sed 's, release .*$,,g' /etc/system-release)"
GRUB_DEFAULT=saved
GRUB_TERMINAL_OUTPUT="console"
GRUB_CMDLINE_LINUX="crashkernel=0M-2G:0M,2G-8G:192M,8G-128G:256M,128G-:384M cryptomgr.notests cgroup.memory=nokmem rcupdate.rcu_cpu_stall_timeout=300 vring_force_dma_api rhgb quiet biosdevname=0 net.ifnames=0 console=tty0 console=ttyS0,115200n8 noibrs nvme_core.io_timeout=4294967295 nvme_core.admin_timeout=4294967295"
GRUB_DISABLE_RECOVERY="true"
GRUB_ENABLE_BLSCFG=true

# grep console /etc/grub2.cfg 
terminal_output console
    linux    /boot/vmlinuz-4.19.90-2102.2.0.0062.el7.x86_64 root=UUID=f81deefa-c459-4ad6-bef7-111 ro net.ifnames=0 biosdevname=0 console=tty0 console=ttyS0,115200n8 crashkernel=512M 
    linux    /boot/vmlinuz-0-rescue-1c6406e0f root=UUID=f81deefa-c459-4ad6-bef7-111 ro net.ifnames=0 biosdevname=0 console=tty0 console=ttyS0,115200n8 crashkernel=512M

参考连接：https://blog.51cto.com/coolsky/3713851

https://blog.51cto.com/coolsky/3713851#:~:text=%E6%96%B0%E5%AE%89%E8%A3%85%E4%B8%80%E5%8F%B0%E8%99%9A%E6%8B%9F%E6%9C%BA%E5%90%8E%EF%BC%8C%E6%98%AF%E6%97%A0%E6%B3%95%E9%80%9A%E8%BF%87virsh%20console,%E5%91%BD%E4%BB%A4%E8%BF%9E%E5%85%A5%E8%99%9A%E6%8B%9F%E6%9C%BA%E4%B8%AD%E7%9A%84%EF%BC%8C%E8%BF%99%E6%97%B6%E6%88%91%E4%BB%AC%E9%9C%80%E8%A6%81%E5%BC%80%E5%90%AF%E8%99%9A%E6%8B%9F%E6%9C%BA%E7%9A%84console%E5%8A%9F%E8%83%BD%E3%80%82%20RHEL%2FCentOS6%20%E4%B8%80%E3%80%81%E6%B7%BB%E5%8A%A0ttyS0%E7%9A%84%E8%AE%B8%E5%8F%AF%EF%BC%8C%E5%85%81%E8%AE%B8root%E7%99%BB%E9%99%86

其他：原文转载

新安装一台虚拟机后，是无法通过virsh console 命令连入虚拟机中的，这时我们需要开启虚拟机的console功能。

RHEL/CentOS6
一、添加ttyS0的许可，允许root登陆
[root@Inf-c6-n0 ~]# echo "ttyS0" >> /etc/securetty

 二、编辑/etc/grub.conf
加入console=ttyS0

登录后复制 
[root@Inf-c6-n0 ~]# cat /etc/grub.conf
# grub.conf generated by anaconda
#
# Note that you do not have to rerun grub after making changes to this file
# NOTICE:  You have a /boot partition.  This means that
#          all kernel and initrd paths are relative to /boot/, eg.
#          root (hd0,0)
#          kernel /vmlinuz-version ro root=/dev/mapper/c01-root
#          initrd /initrd-[generic-]version.img
#boot=/dev/vda
default=0
timeout=5
splashimage=(hd0,0)/grub/splash.xpm.gz
hiddenmenu
title CentOS 6 (2.6.32-754.el6.x86_64)
root (hd0,0)
kernel /vmlinuz-2.6.32-754.el6.x86_64 ro root=/dev/mapper/c01-root rd_NO_LUKS LANG=en_US.UTF-8 rd_NO_MD SYSFONT=latarcyrheb-sun16 crashkernel=auto rd_LVM_LV=c01/root rd_LVM_LV=c01/swap  KEYBOARDTYPE=pc KEYTABLE=us rd_NO_DM rhgb quiet console=ttyS0
initrd /initramfs-2.6.32-754.el6.x86_64.img
-----------------------------------
三、编辑/etc/inittab
在最后一行加入内容 S0:12345:respawn:/sbin/agetty ttyS0 115200

登录后复制 
[root@Inf-c6-n0 ~]# cat /etc/inittab
# inittab is only used by upstart for the default runlevel.
#
# ADDING OTHER CONFIGURATION HERE WILL HAVE NO EFFECT ON YOUR SYSTEM.
#
# System initialization is started by /etc/init/rcS.conf
#
# Individual runlevels are started by /etc/init/rc.conf
#
# Ctrl-Alt-Delete is handled by /etc/init/control-alt-delete.conf
#
# Terminal gettys are handled by /etc/init/tty.conf and /etc/init/serial.conf,
# with configuration in /etc/sysconfig/init.
#
# For information on how to write upstart event handlers, or how
# upstart works, see init(5), init(8), and initctl(8).
#
# Default runlevel. The runlevels used are:
#   0 - halt (Do NOT set initdefault to this)
#   1 - Single user mode
#   2 - Multiuser, without NFS (The same as 3, if you do not have networking)
#   3 - Full multiuser mode
#   4 - unused
#   5 - X11
#   6 - reboot (Do NOT set initdefault to this)
#
id:3:initdefault:
S0:12345:respawn:/sbin/agetty ttyS0 115200
-----------------------------------
三、编辑/etc/inittab
在最后一行加入内容 S0:12345:respawn:/sbin/agetty ttyS0 115200

登录后复制 
[root@Inf-c6-n0 ~]# cat /etc/inittab
# inittab is only used by upstart for the default runlevel.
#
# ADDING OTHER CONFIGURATION HERE WILL HAVE NO EFFECT ON YOUR SYSTEM.
#
# System initialization is started by /etc/init/rcS.conf
#
# Individual runlevels are started by /etc/init/rc.conf
#
# Ctrl-Alt-Delete is handled by /etc/init/control-alt-delete.conf
#
# Terminal gettys are handled by /etc/init/tty.conf and /etc/init/serial.conf,
# with configuration in /etc/sysconfig/init.
#
# For information on how to write upstart event handlers, or how
# upstart works, see init(5), init(8), and initctl(8).
#
# Default runlevel. The runlevels used are:
#   0 - halt (Do NOT set initdefault to this)
#   1 - Single user mode
#   2 - Multiuser, without NFS (The same as 3, if you do not have networking)
#   3 - Full multiuser mode
#   4 - unused
#   5 - X11
#   6 - reboot (Do NOT set initdefault to this)
#
id:3:initdefault:
S0:12345:respawn:/sbin/agetty ttyS0 115200
-----------------------------------
三、编辑/etc/inittab
在最后一行加入内容 S0:12345:respawn:/sbin/agetty ttyS0 115200

登录后复制 
[root@Inf-c6-n0 ~]# cat /etc/inittab
# inittab is only used by upstart for the default runlevel.
#
# ADDING OTHER CONFIGURATION HERE WILL HAVE NO EFFECT ON YOUR SYSTEM.
#
# System initialization is started by /etc/init/rcS.conf
#
# Individual runlevels are started by /etc/init/rc.conf
#
# Ctrl-Alt-Delete is handled by /etc/init/control-alt-delete.conf
#
# Terminal gettys are handled by /etc/init/tty.conf and /etc/init/serial.conf,
# with configuration in /etc/sysconfig/init.
#
# For information on how to write upstart event handlers, or how
# upstart works, see init(5), init(8), and initctl(8).
#
# Default runlevel. The runlevels used are:
#   0 - halt (Do NOT set initdefault to this)
#   1 - Single user mode
#   2 - Multiuser, without NFS (The same as 3, if you do not have networking)
#   3 - Full multiuser mode
#   4 - unused
#   5 - X11
#   6 - reboot (Do NOT set initdefault to this)
#
id:3:initdefault:
S0:12345:respawn:/sbin/agetty ttyS0 115200
-----------------------------------

RHEL/CentOS8
在虚拟机里执行

[root@inf-r8-n0 ~]# grubby --update-kernel=ALL --args="console=ttyS0"
[root@inf-r8-n0 ~]#
[root@inf-r8-n0 ~]# reboot
1.
2.
3.
在宿主机上测试

登录后复制 
[root@localhost vmfs]# virsh start Rocky8
Domain Rocky8 started

[root@localhost vmfs]# virsh console Rocky8
Connected to domain Rocky8
Escape character is ^]
[  OK  ] Started Show Plymouth Boot Screen.
[  OK  ] Started Forward Password Requests to Plymouth Directory Watch.
[  OK  ] Reached target Paths.
[  OK  ] Found device /dev/mapper/r01-root.
[  OK  ] Reached target Initrd Root Device.
[  OK  ] Found device /dev/mapper/r01-swap.
         Starting Resume from hibernation using device /dev/mapper/r01-swap...
[  OK  ] Started Resume from hibernation using device /dev/mapper/r01-swap.
[  OK  ] Reached target Local File Systems (Pre).
[  OK  ] Reached target Local File Systems.
         Starting Create Volatile Files and Directories...
[  OK  ] Started dracut initqueue hook.
         Starting File System Check on /dev/mapper/r01-root...
[  OK  ] Reached target Remote File Systems (Pre).
[  OK  ] Reached target Remote File Systems.
-----------------------------------


https://blog.51cto.com/coolsky/3713851