My system is a intel Atom based board without a vedio card, communication can be carried out through serial port(at baut rate of 115200) and ethernet port. I installed CentOS through PXE, after installation the system reboots for the first time. Following is the last lines output through serial console. After that on response when inputing through keyboard.

[  OK  ] Started Notify NFS peers of a restart.
[  OK  ] Started Logout off all iSCSI sessions on shutdown.
[  OK  ] Reached target Remote File Systems (Pre).
[  OK  ] Reached target Remote File Systems.
         Starting Permit User Sessions...
         Starting Crash recovery kernel arming...
         Starting Availability of block devices...
[  OK  ] Started System Logging Service.
[  OK  ] Started OpenSSH server daemon.
[  OK  ] Started Availability of block devices.
[  OK  ] Started Permit User Sessions.
[  OK  ] Started Job spooling tools.
[  OK  ] Started Serial Getty on ttyS0.
[  OK  ] Reached target Login Prompts.
[  OK  ] Started Command Scheduler.
         Starting Terminate Plymouth Boot Screen...
[  OK  ] Created slice User Slice of root.
[  OK  ] Started Session c1 of user root.
[   20.825375] fuse init (API version 7.22)
****0`3鎬~x饉****[   31.791710] XFS (sdb1): Mounting V5 Filesystem
[   31.875202] XFS (sdb1): Ending clean mount
~x饉[   48.919242] TCP: lp registered

So the login prompt is not output correctly and I cannot input user name and password and login. You can see there are some gibberish characters in the beginning of the last line and last third line. I doubt that those was the login prompt but output in that abnormal pattern due to some reason.

Now I can still login through ssh, and I checked the status of serial-getty@ service.

[root@CentOS ~]# systemctl status [email protected][email protected] - Serial Getty on ttyS0
   Loaded: loaded (/usr/lib/systemd/system/[email protected]; enabled; vendor preset: disabled)
   Active: active (running) since Fri 2015-01-02 00:20:42 CST; 28min ago
     Docs: man:agetty(8)
 Main PID: 5242 (agetty)
   CGroup: /system.slice/system-serial\x2dgetty.slice/[email protected]
           └─5242 /sbin/agetty --keep-baud 115200 ttyS0 linux

Jan 02 00:20:42 CentOS systemd[1]: Started Serial Getty on ttyS0.

So please help and give some advice. Thanks a lot!


1 Answer 1


Seems I found the reason. The ModemManager.service conficts with the ttyS0. When disable this service, booting process recovered.


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