Re: [Qemu-devel] [RFC PATCH v3 4/5] Update documentation for LTTng ust tracing

[Mohamad Gebai <mohamad.gebai@polymtl.ca>]

On 13-10-16 08:05 AM, Alex Bennée wrote:
>>> Running this gives me:
>>>
>>> <quote>
>>> UST events:
>>> -------------
>>> None
>>> </quote>
>>>
>>> Before or after running qemu. What is the mechanism lttng expects to
>>> find out all these events?
>> Either the user should belong the group "tracing", or launch the
>> lttng-sessiond daemon (lttng-sessiond -d).
> <snip>
>
> Hmm I've done both and I get nothing still. I can enable all tracepoints
> though. This could just be a Ubuntu weirdness thing though.

That's weird. I did test it on a clean Ubuntu Precise (in a VM) and I 
didn't have any problem after either one of these steps. Can you please 
make sure that the user belongs to the "tracing" group and that the 
lttng-sessiond daemon is running before running any instance of Qemu. 
Also, Qemu should be running for LTTng to be able to list the events.

Does lttng enable-event -a -u/start/stop/view show any event?

>
> I'm not sure if mentioning the group/daemon requirements in the tracing
> doc is required though. I guess these things can be a little
> package/distro specific?
>
> '

This isn't really specific to Ubuntu, it's the setup of LTTng so I guess 
I could add it to the documentation as well.

Thanks!
Mohamad