Can't see kern.log

[Mrigendra Chaubey]

Hi all,

I am a newbie and following a number of forums to learn kernel programming such as drivers, pin multilexing without using overlays or device tree because I was comfortable with the previous kernel. Kernel version is 3.8.

Well the small problem I am having is

I am using extra folder of derek molly's exploringBB repo. I tried to compile gpio_test.c file as a module in bbb kernel in drivers/gpio folder.

1) If I insmod this driver from home such as

root@beaglebone:~# insmod gpio_test.ko
insmod: can't insert 'gpio_test.ko': No such file or directory

I get this error. So I have to go the particular directory
cd /lib/modules/3.8.13-00770-g97d16ab-dirty/kernel/drivers/gpio and then do the insmod.
Why I can't load from home?

2)I am not  getting log messages for this command
tail -f kern.log
ta
tail: can't open 'kern.log': No such file or directory
tail: no files
why?



[Chad Baker]

insmod doesn't know where the source file is. If you put the complete path name in the command, insmod should be able to locate the file. Try -
insmod /lib/modules/3.8.13-00770-g97d16ab-dirty/kernel/drivers/gpio/gpio_test.ko

Chad

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[John Syne]

On Jan 9, 2017, at 6:49 AM, Mrigendra Chaubey <mrigendr...@gmail.com> wrote:

Hi all,

I am a newbie and following a number of forums to learn kernel programming such as drivers, pin multilexing without using overlays or device tree because I was comfortable with the previous kernel. Kernel version is 3.8.

Well the small problem I am having is

I am using extra folder of derek molly's exploringBB repo. I tried to compile gpio_test.c file as a module in bbb kernel in drivers/gpio folder.

1) If I insmod this driver from home such as

root@beaglebone:~# insmod gpio_test.ko
insmod: can't insert 'gpio_test.ko': No such file or directory

Why not use modprobe to install module:

modprobe gpio_test

To remove module:

modprobe -r gpio_test

Regards,

John

I get this error. So I have to go the particular directory
cd /lib/modules/3.8.13-00770-g97d16ab-dirty/kernel/drivers/gpio and then do the insmod.
Why I can't load from home?

2)I am not  getting log messages for this command
tail -f kern.log
ta
tail: can't open 'kern.log': No such file or directory
tail: no files
why?