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

[Alex Bennée]

address@hidden writes:

> 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.

Ahh that was it. I suggest you change the wording from:

"Package lttng-tools is required for userspace tracing. After running Qemu, 
LTTng
should be able to list all available events:"

to

"Package lttng-tools is required for userspace tracing. While running
and instrumented Qemu, LTTng should be able to list all available events:"

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

Yes, as I said the rest worked fine. With that minor wording fix I'm happy.

Thanks for getting this back into shape :-)

-- 
Alex Bennée