From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Zhang Subject: Re: ftrace doesn't work - 1211 upstream kernel Date: Thu, 13 Dec 2012 10:15:03 +0800 Message-ID: <50C93A27.8080002@gmail.com> References: <50C86A0D.9060009@gmail.com> <50C877EE.60507@nvidia.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <50C877EE.60507-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: =?ISO-8859-1?Q?Terje_Bergstr=F6m?= Cc: "linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" List-Id: linux-tegra@vger.kernel.org Terje, did yo test the ToT(1211) kernel? Could you tell me which ftrace configs you enabled? And what is your kernel command line? Mark On 12/12/2012 08:26 PM, Terje Bergstr=F6m wrote: > On 12.12.2012 13:27, Mark Zhang wrote: >> Hi all, >> >> Has anyone tried to use ftrace to debug upstream kernel? I tried tod= ay >> but the result is, the serial console hung after ftrace enabled(kern= el >> is alive because the Magic SysRq works). >> >> My steps are: >> - Enable CONFIG_FUNCTION_TRACER in kernel config >> - Enter command: echo 0 > /sys/kernel/debug/tracing/tracing_on;echo >> function > /sys/kernel/debug/tracing/current_tracer;echo 1 > >> /proc/sys/kernel/ftrace_dump_on_oops >> - Then sometimes the serial console hangs right after you entered th= e >> command above, or hangs when you try to "cat /sys/kernel/debug/trace= " >> >> I dumped some backtraces(check below, by invoking a system crash >> manually) and hope it helps: >=20 > I'm using ftrace to debug host1x driver + tegradrm, running on Tegra2 > ventana. I just rebased them on linux-next, and I use just the events= , > not function tracing. >=20 > echo 1 >/sys/kernel/debug/tracing/events/host1x/enable > ~/drm/tests/tegra/2d/tegra_2d_tests > cat /sys/kernel/debug/tracing/trace >=20 > I get host1x events as expected. >=20 > Also function tracing works. >=20 > Terje >=20