From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753325AbdGNGyW (ORCPT ); Fri, 14 Jul 2017 02:54:22 -0400 Received: from mga04.intel.com ([192.55.52.120]:36797 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751768AbdGNGyV (ORCPT ); Fri, 14 Jul 2017 02:54:21 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.40,357,1496127600"; d="asc'?scan'208";a="1151433613" From: Felipe Balbi To: Pratyush Anand , Alexander Shishkin , Steven Rostedt , Ingo Molnar Cc: Linux USB , linux-kernel@vger.kernel.org, Chunyan Zhang Subject: Re: [PATCH] usb: gadget: functions: add ftrace export over USB In-Reply-To: <78398669-55b1-a4be-4864-9a3a4ed0707c@redhat.com> References: <20170609061327.17899-1-felipe.balbi@linux.intel.com> <87mv9hqwt8.fsf@linux.intel.com> <78398669-55b1-a4be-4864-9a3a4ed0707c@redhat.com> Date: Fri, 14 Jul 2017 09:53:44 +0300 Message-ID: <87fudz5x1j.fsf@linux.intel.com> MIME-Version: 1.0 Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha256; protocol="application/pgp-signature" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --=-=-= Content-Type: text/plain Content-Transfer-Encoding: quoted-printable Hi, Pratyush Anand writes: > On Friday 09 June 2017 03:58 PM, Felipe Balbi wrote: >> Felipe Balbi writes: >> >>> Allow for ftrace data to be exported over a USB Gadget >>> Controller. With this, we have a potentially very fast pipe for >>> transmitting ftrace data to a Host PC for further analysis. >>> >>> Note that in order to decode the data, one needs access to kernel >>> symbols in order to convert binary data into function names and what >>> not. >>> >>> Signed-off-by: Felipe Balbi >>> --- >>> >>> I wanted to take this through the gadget tree, but there is a >>> dependency with a previous patch of mine adding and extra argument to >>> the ->write() function. Hoping someone else will take it. >> >> just as an extra note here. In order for this to be really useful, it >> would be nice to be able to control what is going to be traced over USB > > Probably you will also need to export *atleast* symbol information. In fu= ture,=20 just keep your vmlinux around. This is not supposed to be shipped on end products, only debug builds. > if this framework is extended to export tracepoint/kprobe/uprobe event da= ta,=20 > then the information like event format etc will also need to be exported. > > What tool do you use on host machine in order to extract information from= this=20 > exported target ring buffer data? > IMHO, standard tools like trace-cmd will not be able to use it as it is. I hacked something together with libusb for testing. Proper tooling is needed, indeed. =2D-=20 balbi --=-=-= Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEElLzh7wn96CXwjh2IzL64meEamQYFAlloangACgkQzL64meEa mQbECw/+PkWLQTxGGaG0C+cRUYrKSUDOnEmgzIxbHUKGghwxFutEEhsr69hf5NN/ Pvzw2B1xwuW1ngm+r8AJ2IGT1DtYoqRcLN0cJjaMozmpvT7JVVvkFfvFN5iASHgz GAT7vKnzblqMVM5Cka/EoW8n5EhMFeKYskgHQgcRkSOY9tHNoAxpSqY95tet8t/s UtJwGCYchRuRCpTeitqnfO4wBLCW5bEdsoOrGdK9K7PQDa+HL+djm9zrAPob5I+C AfyLtB7SsaAmpPbLhU80s2OtvCLQaU7YixNJ/WoYjxO7JqW4LByC4M2AMjRBkHpq YVQRN5WRyPHW17SemEiZtbPA1FUBHf2k55Noa8aBKpQrTRE3ktnI66dH5MFEFTSt p5tyzxsxjOQjnGKcFwM4pXZRJQNZKAG2AtRV1QDiUrJpufvsvlXZQHW90EMLHhBT VCbBr/Cv/Li7XtuLlY/J9O9+0oIjQL84lcmgtQGy5uOjkjTPkoLLdU3yGx4maMSQ VNBtiwS3BwSQ36ijWayJyn5UB+Qo1PwLlRCBjz609aGvJ+ArMKZU8lXX2cKZ9qq6 tLGVpWysW8m64osxLhOVKhOnoqs+Cojto/kMRv6UzzyQzx/ZYLAV2qHUK3WDjES9 +u2fdPQMvm6ChWoJ2DtU02ZHGgwK9rzSknD7LsqE9dsmwgAZLbA= =GV/d -----END PGP SIGNATURE----- --=-=-=--