我的系統是基於intel Atom的主機板，沒有視訊卡，可以透過串列埠（波特率為115200）和乙太網路連接埠進行通訊。我透過PXE安裝了CentOS，安裝後系統第一次重新啟動。以下是透過串行控制台輸出的最後幾行。之後透過鍵盤輸入時響應。
[ 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
所以登入提示無法正確輸出，無法輸入使用者名稱和密碼並登入。您可以看到最後一行和最後第三行的開頭有一些亂碼。我懷疑這些是登入提示，但由於某種原因以異常模式輸出。
現在我仍然可以透過ssh登錄，並且我檢查了serial-getty@服務的狀態。
[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)
man:systemd-getty-generator(8)
http://0pointer.de/blog/projects/serial-console.html
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.
所以請大家幫忙並給一些建議。多謝！
答案1
看來我找到原因了ModemManager.service與ttyS0衝突。停用此服務後，啟動過程恢復。