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Subject: Re: [PATCH] [media] v4l2: export videobuf2 trace points
From: Philipp Zabel <p.zabel@pengutronix.de>
To: Hans Verkuil <hverkuil@xs4all.nl>
Cc: Hans Verkuil <hans.verkuil@cisco.com>,
	Mauro Carvalho Chehab <mchehab@osg.samsung.com>,
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	Kyungmin Park <kyungmin.park@samsung.com>,
	Steven Rostedt <rostedt@goodmis.org>,
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Date: Tue, 28 Jul 2015 10:15:06 +0200
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Am Dienstag, den 28.07.2015, 10:02 +0200 schrieb Hans Verkuil:
> On 07/28/2015 09:55 AM, Philipp Zabel wrote:
> > If videobuf2-core is built as a module, the vb2 trace points must be
> > exported from videodev.o to avoid errors when linking videobuf2-core.
> 
> I'm no tracepoint expert, so I'll just ask: if the tracepoint functionality
> is disabled in the kernel, will this still compile OK?
> 
> That is, will the EXPORT_TRACEPOINT_SYMBOL_GPL() code disappear in that
> case or will it point to absent code/data?

No traces left if CONFIG_TRACEPOINTS not set. include/linux/tracepoint.h
contains:

#ifdef CONFIG_TRACEPOINTS
#define EXPORT_TRACEPOINT_SYMBOL_GPL(name)         \
        EXPORT_SYMBOL_GPL(__tracepoint_##name)
#else /* !CONFIG_TRACEPOINTS */
#define EXPORT_TRACEPOINT_SYMBOL_GPL(name)
#endif

regards
Philipp