From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sakari Ailus Subject: Re: [PATCH v6 01/12] tools lib traceevent: Convert remaining %p[fF] users to %p[sS] Date: Mon, 16 Sep 2019 14:41:59 +0300 Message-ID: <20190916114158.GN5781@paasikivi.fi.intel.com> References: <20190910084707.18380-1-sakari.ailus@linux.intel.com> <20190910084707.18380-2-sakari.ailus@linux.intel.com> <20190910071837.2e9110f8@oasis.local.home> <61a2b2ab4693535850306f396aac2a328e1d5a21.camel@perches.com> <20190910142621.0bec208d@oasis.local.home> <20190910150303.5a0d3904@oasis.local.home> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Joe Perches Cc: Steven Rostedt , Petr Mladek , linux-kernel@vger.kernel.org, rafael@kernel.org, Andy Shevchenko , linux-acpi@vger.kernel.org, devicetree@vger.kernel.org, Rob Herring , Heikki Krogerus , Arnaldo Carvalho de Melo , Tzvetomir Stoyanov , linux-trace-devel@vger.kernel.org, Jiri Olsa , Namhyung Kim List-Id: devicetree@vger.kernel.org Hi Joe, Steven, On Tue, Sep 10, 2019 at 12:44:03PM -0700, Joe Perches wrote: > 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 like %pnfw may be simpler. %p[Ff]w does not exist (I grepped for it) in older kernels since v3.0. So kernel support for %p[fF] and %pfw are mutually exclusive. If you're ok with that, I could change the patch to check %pf isn't followed by 'w', in order to support %pf on older kernels. Although that still does not address using older tooling on newer kernels with support for %pfw. If you think that's an issue, I'll opt for another extension than %pfw, which I chose originally since it's memorable --- fw for fwnode (names, paths, and probably more in the future). -- Regards, Sakari Ailus sakari.ailus@linux.intel.com