Re: pr_info in driver question

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On 7/6/22 10:58, A mp wrote:
I believe I tried that, I seen a similar solution on stack overflow, something about changing the log level?

That should work since pr_info is just a macro:

/**
 * pr_info - Print an info-level message
 * @fmt: format string
 * @...: arguments for the format string
 *
* This macro expands to a printk with KERN_INFO loglevel. It uses pr_fmt() to
 * generate the format string.
 */
#define pr_info(fmt, ...) \
        printk(KERN_INFO pr_fmt(fmt), ##__VA_ARGS__)


and you're setting the log level even higher to DEBUG.
cat /proc/sys/kernel/printk shows you the current log level




Any other suggestions perhaps?

Thanks,

Andrew.
On Wed, Jul 06, 2022 at 10:53:12AM +0300, Denis Kirjanov wrote:


On 7/6/22 09:47, A mp wrote:
Hi everyone,

My name is Andrew.

Recently, I went through the Linux Foundations intro to kernel development course. As part of the course, it gets us to put a print statement inside of the uvcvideo driver, recompile the kernel and then load the module and check dmesg for the print statement.

After several attempts, I was unable to find this print statement inside of dmesg. I know that the modified drier was compiling successfully and my custom kernel was indeed installed but no idea about this pr_info statement.

I tried this in Ubuntu and Fedora inside of virtualbox. Not sure if that would make any difference.

echo "7" > /proc/sys/kernel/printk

and make sure that you have your module listed in lsmod


Thanks,

Andrew.


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