如何设置ubuntu系统的串口输出(一)
1. 平台:intel X86 baytrail平台
2. 由于开发模式需要查看内核串口输出,所以需要将linux系统从开机到系统引导起来的部分都定向到串口,那么如何设置呢?
安装ubuntu系统后(这里装的是14.10版本的ubuntu系统)
(1)首先设置grub参数:
修改/etc/default/grub文件:
修改如下内容为:
GRUB_CMDLINE_LINUX_DEFAULT="text console=tty0 console=ttyS0,115200n8"
然后增加一行:
GRUB_SERIAL_COMMAND="serial --unit=0 --speed=115200 --word=8 --parity=no --stop=1"
然后执行update-grub,使配置生效
(2)然后在/etc/init/目录中创建ttyS0.conf,内容如下:
#ttyS0 - getty
start on rc RUNLEVEL=[2345]
stop on runlevel [!2345]
respawn
exec /sbin/getty -L 115200 ttyS0 vt100
遗留问题:
系统起来后,在串口部分只显示到:
* Starting regular background program processing daemon[ OK ]
* Starting Signal sysvinit that alsa-utils tasks are complete[ OK ]
* Starting CPU interrupts balancing daemon[ OK ]
* Stopping save kernel messages[ OK ]
* Stopping Restore Sound Card State[ OK ]
* Starting cups-browsed - Bonjour remote printer browsing daemon[ OK ]
* Starting automatic crash report generation[ OK ]
* Starting configure virtual network devices[ OK ]
[ OK ]toring resolver state...
[ OK ]rting uuid generator uuidd
* speech-dispatcher disabled; edit /etc/default/speech-dispatcher
saned disabled; edit /etc/default/saned
* Stopping System V runlevel compatibility[ OK ]
* Stopping cold plug devices[ OK ]
* Stopping log initial device creation[ OK ]
* Starting save udev log and update rules[ OK ]
[ 150.593006] systemd-logind[947]: Failed to start unit user@1000.service: Unknown unit: user@1000.service
[ 150.602779] systemd-logind[947]: Failed to start user service: Unknown unit: user@1000.service
然后在VGA上有显示登录,但是串口上没有显示
这里需要进一步研究
不过总算将这一步做出来了,后面的问题就是开机脚本配置的问题了
另外也说明了,之前购买的baytrail主板确实串口硬件有问题,小厂自己做的主板不如品牌主板给力