Modify the default log level

1、log Grade introduction

        log Level common 8 individual , Namely ： 

Macro definition	Level	describe
KERN_EMERG	0	Emergency message , This information will cause the system to crash
KERN_ALERT	1	Prompt for some immediate action
KERN_CRIT	2	The key information , There are usually serious software or hardware problems
KERN_ERR	3	Usually used to report errors , For example, device drivers are usually used to report hardware operation failures, etc
KERN_WARNING	4	Warning message , Used to warn against problems that do not cause serious system exceptions
KERN_NOTICE	5	Used in normal but noteworthy situations , For example, a large number of safety related log
KERN_INFO	6	Information , Many drivers will use this level to print when the hardware starts Log
KERN_DEBUG	7	For printing debugging information

2、 Dynamic modification log Grade

         Get into adb shell

        Use cat proc/sys/kernel/printk View the current log Grade , Such as ： 

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         Use echo 3 6 1 7 > proc/sys/kernel/printk Modify level

         notes ： Just change the first number , The smaller the numerical , The higher the priority .

3、 Change the default log Grade

         If you modify the default log Grade , The corresponding file configuration information needs to be modified ;

         File path ：arch/arm/boot/dts/xxx.dts, Such as ：

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         Just put the loglevel You can modify the value of .