qemu启动ubuntu直接重定向到终端串口

ubuntu虚拟机中设置：

systemctl set-default multi-user.target

修改grub引导
GRUB_CMDLINE_LINUX="console=tty0 console=ttyS0,115200"
GRUB_TERMINAL=serial
GRUB_SERIAL_COMMAND="serial --speed=115200 --unit=0 --word=8 --parity=no --stop=1"

qemu启动命令修改

/qemu-5.1.0/build/x86_64-softmmu/qemu-system-x86_64 \
  -enable-kvm \
  -m 4G \
  -vga qxl \
  -display default \
  -device e1000,netdev=net0 \
  -netdev user,id=net0,net=192.168.20.0/24,dhcpstart=192.168.20.20 \
  -smp 4\
  -drive file=/ImageStore/ruguang/ji/ubuntu-20.04.1-desktop-amd64.qcow2,if=virtio \
  -nographic -serial mon:stdio
#  -spice port=8899,addr=172.17.81.26,disable-ticketing