内核的终端口修改

开发板linux kernel  log 控制台串口输出是在commandline中设置的, am335x默认串口输出是ttyO0

commandline: consoleblank=0 console=ttyO0,115200n8  root=/dev/mmcblk0p2 rootflags=data=journal rootwait ro fsck.repair=yes

如果要禁止kernel log在串口输出, 可在barebox中设置

barebox@Phytec phyCORE AM335x:/ nv linux.bootargs.console=console=off
nv variable modified, will save nv variables on shutdown
barebox@Phytec phyCORE AM335x:/ saveenv
saving environment

此时commandline已经修改为

commandline: consoleblank=0 console=off  root=/dev/mmcblk0p2 rootflags=data=journal rootwait ro fsck.repair=yes

kernel log也不会在串口输出了, 如果kernel log需要更改为其他串口输出, 也是按照上诉方法把commandline 的console设为其他串口.

linux 登录界面串口终端修改

按照上诉方法kernel log在串口禁止输出设置后, 启动完成后, 串口终端仍有以下登录界面

Loading ARM Linux zImage '/mnt/mmc0.0/linuximage'
Loading devicetree from '/mnt/mmc0.0/oftree'
commandline: consoleblank=0 console=off  root=/dev/mmcblk0p2 rootflags=data=journal rootwait ro fsck.repair=yes

 ____   _   _ __   __ _____  _____   ____
|  _ \ | | | |\ \ / /|_   _|| ____| / ___|
| |_) || |_| | \ V /   | |  |  _|  | |
|  __/ |  _  |  | |    | |  | |___ | |___
|_|    |_| |_|  |_|    |_|  |_____| \____|

__   __  ___    ____  _   _  ____   _____
\ \ / / / _ \  / ___|| | | ||  _ \ |_   _|
 \ V / | | | || |  _ | | | || |_) |  | |
  | |  | |_| || |_| || |_| ||  _ <   | |
  |_|   \___/  \____| \___/ |_| \_\  |_|


Yogurt (Phytec Example Distribution) BSP-Yocto-AM335x-PD17.2.2 phycore-am335x-1 ttyO0

phycore-am335x-1 login: root
root@phycore-am335x-1:~#

通过systemctl查找该服务名称

root@phycore-am335x-1:~# systemctl | grep getty
getty@tty1.service                                                                           loaded active running   Getty on tty1                                                            
serial-getty@ttyO0.service                                                                   loaded active running   Serial Getty on ttyO0                                                    
system-getty.slice                                                                           loaded active active    system-getty.slice                                                       
system-serial\x2dgetty.slice                                                                 loaded active active    system-serial\x2dgetty.slice                                             
getty.target                                                                                 loaded active active    Login Prompts

如果需要禁止这个登录界面串口输出的话, 可禁止该服务

root@phycore-am335x-1:~# systemctl disable serial-getty@ttyO0.service
Removed /etc/systemd/system/getty.target.wants/serial-getty@ttyO0.service.
root@phycore-am335x-1:~# sync

重启之后, 该服务已经被禁止了, 串口0终端就不会再有登录界面了.

如果需要将该登录界面改为在其他串口中显示, 可使能对应串口的getty服务.

root@phycore-am335x-1:~# systemctl enable serial-getty@ttyO1.service

Linux串口终端root用户自动登陆

修改/lib/systemd/system/serial-getty@.service文件, 

将service 文件中的

ExecStart=-/sbin/agetty -8 -L %I 115200 $TERM

修改为

ExecStart=-/sbin/agetty -8 -L -a root %I 115200 $TERM

保存后执行sync命令, 重启命令串口终端就会自动登陆root用户.

关闭显示在LCD上的终端口

lcd 关闭qt程序时, 也会显示一个控制台终端界面

 ____   _   _ __   __ _____  _____   ____
|  _ \ | | | |\ \ / /|_   _|| ____| / ___|
| |_) || |_| | \ V /   | |  |  _|  | |
|  __/ |  _  |  | |    | |  | |___ | |___
|_|    |_| |_|  |_|    |_|  |_____| \____|

__   __  ___    ____  _   _  ____   _____
\ \ / / / _ \  / ___|| | | ||  _ \ |_   _|
 \ V / | | | || |  _ | | | || |_) |  | |
  | |  | |_| || |_| || |_| ||  _ <   | |
  |_|   \___/  \____| \___/ |_| \_\  |_|

Yogurt (Phytec Example Distribution) BSP-Yocto-AM335x-PD17.2.2 phycore-am335x-1 tty1

phycore-am335x-1 login:

如果需要关闭该控制台终端界面, 可禁止该服务

root@phycore-am335x-1:~# systemctl disable getty@tty1.service
Removed /etc/systemd/system/getty.target.wants/getty@tty1.service.
root@phycore-am335x-1:~# sync

编译好的镜像默认不开启这个终端, 可以在BSP包中自定义的layer上增加recipes-core/systemd/systemd_%.bbappend文件, 内容如下

[meta-custom]/recipes-core/systemd/systemd_%.bbappend
do_install_append() {
     rm ${D}${sysconfdir}/systemd/system/getty.target.wants/getty@tty1.service
}
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