Re: [PATCH] tracing: add trace console

From: Johannes Berg <johannes@sipsolutions.net>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Christoph Hellwig <hch@infradead.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Frederic Weisbecker <fweisbec@gmail.com>,
	Ingo Molnar <mingo@redhat.com>
Subject: Re: [PATCH] tracing: add trace console
Date: Wed, 16 Nov 2011 17:45:02 +0100	[thread overview]
Message-ID: <1321461902.4502.14.camel@jlt3.sipsolutions.net> (raw)
In-Reply-To: <1321461693.4181.26.camel@frodo>

On Wed, 2011-11-16 at 11:41 -0500, Steven Rostedt wrote:

> > That's possible, basically adding a tracepoints to printk -- that would
> > even catch everything and not require setting the console level (which
> > has its advantages too since other consoles might be slow).
> > 
> > It's a completely different thing though. I did it this way because it
> > was trivial to do out of tree for a quick test I was doing yesterday.
> > Doing it the other way is obviously more intrusive in core code.
> 
> I'm not sure it would be too invasive. Think you could get something
> working?

I briefly looked at it just after writing the email, but quickly got
lost in printk.c because of the multi-line handling it has. We could
instead trace each call to printk(), so the multi-line stuff would end
up in multiple events, but all of that code is too much vodoo for me :)

johannes