[ltt-dev] migrating from lttctl.40 to lttctl.47

[Mathieu Desnoyers]

I guess the best way to find out what changes I've done to lttctl within
a whole year is to dig in the source, the mailing list and the
compatibility list on the ltt.polymtl.ca website, as I myself cannot
answer to this question without doing this process.

The best way for you would be to install both versions of lttctl, lttd
and lttv in different directories and to create a wrapper script which
detects the kernel version and uses the appropriate binary.

Note that the trace format have changed between the "xml event
description" based traces and the "marker" based traces. Therefore you
also need to upgrade lttv and maybe lttd too.

As a matter of fact, it's better for you to perform as few modifications
to the lttd, lttctl and lttv core as you can if you want to be able to
keep up with the newer versions when they appear, except, of course,
modifications send to upstream and well integrated in the project.

Mathieu


* Laurent Chavey (chavey at google.com) wrote:
> Great news.
> Since I have machines running different version of the kernel, this requires
> me to have a version of lttctl that is "compatible" across the
> different kernel versions
> (that is why I have lttctl version 40 and 47).
> How much is the control interface changing between version of lttng ?
> 
> (from the simple diff, I did not see anything major between the two
> versions listed
> above)
> 
> On Mon, Jul 14, 2008 at 2:21 PM, Mathieu Desnoyers
> <compudj at krystal.dyndns.org> wrote:
> > * Laurent Chavey (chavey at google.com) wrote:
> >> in lttctl 40, we use to have xml files describing the various facilities.
> >> when migrating to a newer version of lttng, I noticed that the facilities
> >> are not present anymore.
> >>
> >> - what do we do about those xml files, are they still needed ?
> >>    if not, then how are custom facilities supported ?
> >>
> >> thx
> >>
> >
> > Hi Laurent,
> >
> > The event descriptions are now fully contained in the markers. The
> > kernel exports the event description through the control/facilities_*
> > channel files automatically.
> >
> > So, basically, adding a new event is as simple as adding a new marker in
> > the kernel code.
> >
> > Userspace tracing work is "work in progress", but works work x86 and
> > will soon work for x86_64. It will use a userspace version of the marker
> > infrastructure.
> >
> > Mathieu
> >
> >
> > --
> > Mathieu Desnoyers
> > OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68
> >
> 

-- 
Mathieu Desnoyers
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68