Dear all, I am working on a kernel module that incorporate both pr_debug and pr_warn. I would like to see pr_debug messages from dmesg. What I followed is to specify kernel parameter by saying "loglevel=7". This can be seen confirmed from /proc/cmdline. But still, I donot get pr_debug level messages either from dmesg or from /var/log/messages. I also tried echo 7 > /proc/sys/kernel/printk. It does not return what I expect, either. Let me know what I am missing. Thank you very much in advance. Cheers, Wenda Ni, Ph.D.
On Mon, Oct 17, 2016 at 07:17:32PM -0400, Wenda Ni wrote:
Dear all,
I am working on a kernel module that incorporate both pr_debug and pr_warn. I would like to see pr_debug messages from dmesg.
What I followed is to specify kernel parameter by saying "loglevel=7". This can be seen confirmed from /proc/cmdline. But still, I donot get pr_debug level messages either from dmesg or from /var/log/messages. I also tried echo 7 > /proc/sys/kernel/printk. It does not return what I expect, either.
Let me know what I am missing. Thank you very much in advance.
Cheers,
Wenda Ni, Ph.D.
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Hello Wenda, I encountered the same issue a while ago. As stated here: http://elinux.org/Debugging_by_printing pr_debug is replaced with an empty statement unless the kernel is compiled with DEBUG. So if you just want to play with printing kernel debug logs, just define the DEBUG macro in your module source file for testing. I also observed that without a new line character at the end of the string passed to pr_debug, I could not find the log line in dmesg output. Not sure where this comes from. -- Thibaut SAUTEREAU
Hi Wenda, pr_debug needs you to define the DEBUG macro to activate it. Check: http://stackoverflow.com/questions/28936199/pr-debug-not-giving-any-output and the kernel docs, https://www.kernel.org/doc/local/pr_debug.txt Joel On Mon, Oct 17, 2016 at 4:17 PM, Wenda Ni <wonda.ni@gmail.com> wrote:
Dear all,
I am working on a kernel module that incorporate both pr_debug and pr_warn. I would like to see pr_debug messages from dmesg.
What I followed is to specify kernel parameter by saying "loglevel=7". This can be seen confirmed from /proc/cmdline. But still, I donot get pr_debug level messages either from dmesg or from /var/log/messages. I also tried echo 7 > /proc/sys/kernel/printk. It does not return what I expect, either.
Let me know what I am missing. Thank you very much in advance.
Cheers,
Wenda Ni, Ph.D.
_______________________________________________ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Hi Joel, It works by specifying ccflags-y += -DDEBUG in the Makefile. Thank you for the info!!!! Cheers, Wenda Ni, Ph.D. On Mon, Oct 17, 2016 at 7:48 PM, Joel Fernandes <agnel.joel@gmail.com> wrote:
Hi Wenda,
pr_debug needs you to define the DEBUG macro to activate it.
Check: http://stackoverflow.com/questions/28936199/pr-debug-not-giving-any-output
and the kernel docs, https://www.kernel.org/doc/local/pr_debug.txt
Joel
On Mon, Oct 17, 2016 at 4:17 PM, Wenda Ni <wonda.ni@gmail.com> wrote:
Dear all,
I am working on a kernel module that incorporate both pr_debug and pr_warn. I would like to see pr_debug messages from dmesg.
What I followed is to specify kernel parameter by saying "loglevel=7". This can be seen confirmed from /proc/cmdline. But still, I donot get pr_debug level messages either from dmesg or from /var/log/messages. I also tried echo 7 > /proc/sys/kernel/printk. It does not return what I expect, either.
Let me know what I am missing. Thank you very much in advance.
Cheers,
Wenda Ni, Ph.D.
_______________________________________________ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
participants (3)
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Joel Fernandes -
Thibaut SAUTEREAU -
Wenda Ni