先查看系统是否有 serial-getty@.service 模板，查看设备串口节点是 /dev/ttyFIQ0，可通过自定义 serial-getty@.service 单元文件来实现
bash
$ dmesg |grep tty
[ 5.032998] systemd[1]: Created slice system-getty.slice - Slice /system/getty.
[ 5.041364] systemd[1]: Created slice system-serial\x2dgetty.slice - Slice /system/serial-getty.
[ 5.045980] systemd[1]: Expecting device dev-ttyFIQ0.device - /dev/ttyFIQ0...不要直接修改 /lib/systemd/system/serial-getty@.service，而是复制一份到 /etc/systemd/system/ 下并重命名，以便针对特定串口进行配置：
bash
sudo cp /lib/systemd/system/serial-getty@.service /etc/systemd/system/serial-getty@ttyFIQ0.service
sudo vim /etc/systemd/system/serial-getty@ttyFIQ0.service
找到 ExecStart= 行，将其修改为：因为用户名是openkylin
ExecStart=-/sbin/agetty -a openkylin --keep-baud 1500000,115200 %I $ TERM-a openkylin：表示自动以 openkylin 用户登录
%I 会被替换为 ttyFIQ0，即设备路径 /dev/ttyFIQ0
--keep-baud 是为了兼容不同波特率（根据你的硬件调整，若确定波特率可简化为 - 1500000）
设置完 serial-getty@ttyFIQ0.service 之后，就已经能自动登录了
bash
openkylin@openkylin:~$ dmesg |grep tty
[ 1.285665] Kernel command line: storagemedia=emmc androidboot.storagemedia=emmc androidboot.mode=normal androidboot.verifiedbootstate=orange rw rootwait earlycon=uart8250,mmio32,0xfe660000 console=ttyFIQ0 root=PARTUUID=614e0000-0000
[ 1.604248] Registered FIQ tty driver
[ 2.316094] printk: console [ttyFIQ0] enabled
[ 2.317539] Registered fiq debugger ttyFIQ0
[ 2.447218] fe670000.serial: ttyS3 at MMIO 0xfe670000 (irq = 33, base_baud = 1500000) is a 16550A
[ 2.448004] fe680000.serial: ttyS4 at MMIO 0xfe680000 (irq = 34, base_baud = 1500000) is a 16550A
[ 2.448701] fe690000.serial: ttyS5 at MMIO 0xfe690000 (irq = 35, base_baud = 1500000) is a 16550A
[ 2.449453] fe6b0000.serial: ttyS7 at MMIO 0xfe6b0000 (irq = 36, base_baud = 1500000) is a 16550A
[ 2.450022] fe6d0000.serial: ttyS9 at MMIO 0xfe6d0000 (irq = 37, base_baud = 1500000) is a 16550A
[ 5.032998] systemd[1]: Created slice system-getty.slice - Slice /system/getty.
[ 5.041364] systemd[1]: Created slice system-serial\x2dgetty.slice - Slice /system/serial-getty.
[ 5.045980] systemd[1]: Expecting device dev-ttyFIQ0.device - /dev/ttyFIQ0...
bash
$ cat /etc/systemd/system/serial-getty@ttyFIQ0.service
# SPDX-License-Identifier: LGPL-2.1-or-later
#
# This file is part of systemd.
#
# systemd is free software; you can redistribute it and/or modify it
# under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation; either version 2.1 of the License, or
# (at your option) any later version.
[Unit]
Description=Serial Getty on %I
Documentation=man:agetty(8) man:systemd-getty-generator(8)
Documentation=https://0pointer.de/blog/projects/serial-console.html
BindsTo=dev-%i.device
After=dev-%i.device systemd-user-sessions.service plymouth-quit-wait.service getty-pre.target
After=rc-local.service
# If additional gettys are spawned during boot then we should make
# sure that this is synchronized before getty.target, even though
# getty.target didn't actually pull it in.
Before=getty.target
IgnoreOnIsolate=yes
# IgnoreOnIsolate causes issues with sulogin, if someone isolates
# rescue.target or starts rescue.service from multi-user.target or
# graphical.target.
Conflicts=rescue.service
Before=rescue.service
[Service]
# The '-o' option value tells agetty to replace 'login' arguments with an
# option to preserve environment (-p), followed by '--' for safety, and then
# the entered username.
ExecStart=-/sbin/agetty -a openkylin --keep-baud 1500000,115200 %I $TERM
Type=idle
Restart=always
UtmpIdentifier=%I
StandardInput=tty
StandardOutput=tty
TTYPath=/dev/%I
TTYReset=yes
TTYVHangup=yes
IgnoreSIGPIPE=no
SendSIGHUP=yes
ImportCredential=agetty.*
ImportCredential=login.*
[Install]
WantedBy=getty.target