hwpmc ktrdump: failed to resolve ktr symbols

[Navdeep Parhar]

On 2019-08-30 03:54, shreyank amartya wrote:
> Hi,
> 
> I'm trying to collect traces from hwpmc module. I compiled the module with
> -DHWPMC_DEBUG option and set the sysctl kern.hwpmc.debugflags but I'm
> unable to retrive the traces using ktrdump. I get this error message:
> 
> ktrdump: failed to resolve ktr symbols
> 
> I'm guessing that this error occurs because the symbols for hwpmc module
> (compiled and loaded separately) are not a part of kernel. If this is the
> case, then how do I get those symbols. In the ktr man page its also
> mentioned that ddb and gdb can retrieve ktraces.
> 
> I found the ddb command show ktr. But how do I invoke ddb (without a panic)?

sysctl debug.kdb.enter=1

> 
> I'm unable to find how can I use gdb to view the traces (I launched kgdb
> but could not find a command to show kernel traces).
> 
> Any idea on how to get ktrdump working? Or get the kernel traces.

You need a kernel with KTR support.  See ktr(4) for a full list of
the options and other details.  See "sysctl kern.conftxt" for what's
in your running kernel.

Regards,
Navdeep