Re: [PATCH v6 01/12] tools lib traceevent: Convert remaining %p[fF] users to %p[sS]

From: Joe Perches
Date: Tue Sep 10 2019 - 15:44:10 EST

On Tue, 2019-09-10 at 15:03 -0400, Steven Rostedt wrote:
> On Tue, 10 Sep 2019 11:42:06 -0700
> > btw:
> >
> > Is there kernel version information available in
> > trace output files?
> Not really. This is just a library that parses the trace event formats,
> there's not kernel versions passed in, but we do use variations in
> formats and such to determine what is supported.
> > If so, it might be reasonable to change the tooling
> > there instead.
> >
> Actually, I think we could just look to see if "%pfw" is used and fall
> to that, otherwise consider it an older kernel and do it the original
> way.

Well, if you think that works, OK great.

But could that work?
How would an individual trace record know if
another trace record used %pfw?

Perhaps not reusing %pf, marking it reserved
for a period of years, and using another unused
prefix %p<type> like %pnfw may be simpler.