From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:46711) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WSSfW-0004oT-H6 for qemu-devel@nongnu.org; Tue, 25 Mar 2014 10:49:39 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WSSfR-0007Te-W0 for qemu-devel@nongnu.org; Tue, 25 Mar 2014 10:49:34 -0400 Received: from static.88-198-71-155.clients.your-server.de ([88.198.71.155]:52031 helo=socrates.bennee.com) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WSSfR-0007TZ-P4 for qemu-devel@nongnu.org; Tue, 25 Mar 2014 10:49:29 -0400 References: <1395680694-27758-1-git-send-email-alex.bennee@linaro.org> <20140325095627.GO17172@stefanha-thinkpad.redhat.com> From: Alex =?utf-8?Q?Benn=C3=A9e?= In-reply-to: <20140325095627.GO17172@stefanha-thinkpad.redhat.com> Date: Tue, 25 Mar 2014 14:49:42 +0000 Message-ID: <8761n2nxix.fsf@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Subject: Re: [Qemu-devel] [PATCH] trace: teach lttng backend to use format strings List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Stefan Hajnoczi Cc: Mohamad Gebai , mohamad.gebai@gmail.com, qemu-devel@nongnu.org, vilanova@ac.upc.edu Stefan Hajnoczi writes: > On Mon, Mar 24, 2014 at 05:04:54PM +0000, alex.bennee@linaro.org wrote: >> From: Alex Bennée >> >> This makes the UST backend pay attention to the format string arguments >> that are defined when defining payload data. With this you can now >> ensure integers are reported in hex mode if you want. >> >> Signed-off-by: Alex Bennée >> --- >> scripts/tracetool/__init__.py | 13 +++++++++++-- >> scripts/tracetool/backend/ust.py | 16 ++++++++++++---- >> 2 files changed, 23 insertions(+), 6 deletions(-) > > How are strings handled, can LTTng copy them from the QEMU process' > memory space? lttng provides ctf_string for passing strings to the payload. But I wouldn't expect to use them for the result of format string calculations as that would defeat the point of the low impact tracing. There are a number of trace-events that pass strings for various things. I've not actually experimented with the output of any of them though. > > Stefan -- Alex Bennée