如何在内核中显示当前时间? [英] How can i print current time in kernel?

问题描述

我是linux的初学者.(对不起我英语不好)我应该打印当前时间，并通过linux中的系统调用来执行某些操作.我做了其他事情，但无法显示当前时间.我写得像

i'm a beginner of linux. (sorry about my poor english) I should print current time and do something through system call in linux. I did other things but failed to print current time.. I wrote like

#include<linux/kernel.h>
#include<linux/time.h>
...
asmlinkage long sys_printtime(void) {
     ...
     struct timeval time;
     struct tm tm1;
     ...

     do_gettimeofday(&time);
     local_time=(u32)(time.tv_sec -(sys_tz.tz_minuteswest * 60));
     time_to_tm(local_time,(3600*9),&tm1);
     printk(KERN_DEBUG "time @(%04d-%02d-%02d %02d:%02d:%02d)\n", tm1.tm_year+1900,tm1.tm_mon+1,tm1.tm_mday,tm1.tm_hour,tm1.tm_min,tm1.tm_sec);
    ...
    return 0;
}

但它不起作用.

该错误表明我不能使用do_gettimeofday，我终于知道我不能再使用do_gettimeofday，因为kernel5不支持.我在Google和stackoverflow上进行了搜索，但我不知道如何在kernel5中打印当前时间.有人可以帮助我吗?

The error said i can not use do_gettimeofday, and i finally knew that i can not use do_gettimeofday anymore because kernel5 doesn't support. I searched on google and stackoverflow, but i don't know how to print current time in kernel5.. anybody can help me?

推荐答案

是的，由于 https://www.kernel.org/doc/html/latest/core-api/timekeeping.html .

Yes, do_gettimeofday has been removed because of y2038 problem. Instead the kernel provides time interfaces which you can use as per your need. Check the documentation https://www.kernel.org/doc/html/latest/core-api/timekeeping.html.

例如，您有 ktime_get_ts64(struct timespec64 * ts)，它将为您提供以秒和纳秒为单位的时间.

For example, you have ktime_get_ts64(struct timespec64 *ts) which will provide you time in seconds and nanoseconds.

struct timespec64 {
    time64_t    tv_sec;         /* seconds */
    long        tv_nsec;        /* nanoseconds */
};

如果只需要几纳秒，则可以使用 u64 ktime_get_ns(void).请检查上面的文档以适合您的目的.您也可以检查 timekeeping.h 和 ktime.h 了解更多信息.

If you only want in nanoseconds, you can use u64 ktime_get_ns(void). Please check the documentation above for what suits your purpose. Also you can check timekeeping.h and ktime.h for further information.

如果要查找示例，请使用 grep -rni< func name> 或使用 cscope 在内核源代码中搜索函数名称.您也可以在此处

If you want to find an example just search the function name in the kernel source either using grep -rni <func name> or use cscope. You can also search it online here

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