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From: Steven Rostedt <rostedt@goodmis.org>
To: Sakari Ailus <sakari.ailus@linux.intel.com>
Cc: Joe Perches <joe@perches.com>, Petr Mladek <pmladek@suse.com>,
	linux-kernel@vger.kernel.org, rafael@kernel.org,
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	linux-acpi@vger.kernel.org, devicetree@vger.kernel.org,
	Rob Herring <robh@kernel.org>,
	Heikki Krogerus <heikki.krogerus@linux.intel.com>,
	Arnaldo Carvalho de Melo <acme@redhat.com>,
	Tzvetomir Stoyanov <tstoyanov@vmware.com>,
	linux-trace-devel@vger.kernel.org, Jiri Olsa <jolsa@redhat.com>,
	Namhyung Kim <namhyung@kernel.org>
Subject: Re: [PATCH v6 01/12] tools lib traceevent: Convert remaining %p[fF] users to %p[sS]
Date: Mon, 16 Sep 2019 10:37:55 -0400	[thread overview]
Message-ID: <20190916103755.4c19eda9@gandalf.local.home> (raw)
In-Reply-To: <20190916114158.GN5781@paasikivi.fi.intel.com>

On Mon, 16 Sep 2019 14:41:59 +0300
Sakari Ailus <sakari.ailus@linux.intel.com> wrote:

> > 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.  
> 
> %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.

I think that's what I suggested to do.

> 
> Although that still does not address using older tooling on newer kernels
> with support for %pfw.

That should be fine. I don't think it will crash those tools, they will
just give out wrong information, and if people complain, we can try to
get them to use the newer version of those tools ;-) (hopefully they
don't complain to Linus).

> 
> 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).
> 

I'm fine with the switch, as long as newer tools know how to handle it.

Make sure we also add a comment in the Linux kernel code that states
that older kernels use to have 'f' and 'F' and that new tools look for
'fw' to denote that this isn't an older kernel. This way, people will
hopefully not add another 'fX' pointer name.

-- Steve

  reply	other threads:[~2019-09-16 14:37 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-10  8:46 [PATCH v6 00/12] Device property improvements, add %pfw format specifier Sakari Ailus
2019-09-10  8:46 ` [PATCH v6 01/12] tools lib traceevent: Convert remaining %p[fF] users to %p[sS] Sakari Ailus
2019-09-10  9:22   ` Andy Shevchenko
2019-09-10 11:18   ` Steven Rostedt
2019-09-10 17:18     ` Joe Perches
2019-09-10 18:26       ` Steven Rostedt
2019-09-10 18:42         ` Joe Perches
2019-09-10 19:03           ` Steven Rostedt
2019-09-10 19:44             ` Joe Perches
2019-09-16 11:41               ` Sakari Ailus
2019-09-16 14:37                 ` Steven Rostedt [this message]
2019-09-18 13:08                   ` Sakari Ailus
2019-09-10  8:46 ` [PATCH v6 02/12] software node: Get reference to parent swnode in get_parent op Sakari Ailus
2019-09-10  8:46 ` [PATCH v6 03/12] software node: Make argument to to_software_node const Sakari Ailus
2019-09-10  8:46 ` [PATCH v6 04/12] device property: Move fwnode_get_parent() up Sakari Ailus
2019-09-10  8:47 ` [PATCH v6 05/12] device property: Add functions for accessing node's parents Sakari Ailus
2019-09-10  8:47 ` [PATCH v6 06/12] device property: Add fwnode_get_name for returning the name of a node Sakari Ailus
2019-09-10  8:47 ` [PATCH v6 07/12] device property: Add a function to obtain a node's prefix Sakari Ailus
2019-09-10  8:47 ` [PATCH v6 08/12] lib/vsprintf: Remove support for %pF and %pf in favour of %pS and %ps Sakari Ailus
2019-09-10  8:47 ` [PATCH v6 09/12] lib/vsprintf: Make use of fwnode API to obtain node names and separators Sakari Ailus
2019-09-10  8:47 ` [PATCH v6 10/12] lib/vsprintf: OF nodes are first and foremost, struct device_nodes Sakari Ailus
2019-09-10  8:47 ` [PATCH v6 11/12] lib/vsprintf: Add %pfw conversion specifier for printing fwnode names Sakari Ailus
2019-09-10 10:21   ` Joe Perches
2019-09-18 13:11     ` Sakari Ailus
2019-09-10  8:47 ` [PATCH v6 12/12] lib/test_printf: Add tests for %pfw printk modifier Sakari Ailus

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