Re: Crash in msm serial on dragonboard with ftrace bootargs

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On 10/17/2018 2:21 AM, Stephen Boyd wrote:
Quoting Sai Prakash Ranjan (2018-10-16 12:35:57)
On 10/17/2018 12:45 AM, Steven Rostedt wrote:
On Wed, 17 Oct 2018 00:36:05 +0530
Sai Prakash Ranjan <saiprakash.ranjan@xxxxxxxxxxxxxx> wrote:

On 10/17/2018 12:33 AM, Steven Rostedt wrote:
On Wed, 17 Oct 2018 00:31:03 +0530
Sai Prakash Ranjan <saiprakash.ranjan@xxxxxxxxxxxxxx> wrote:
Haa seems like you are right! With "ftrace=function
ftrace_filter=msm_read" , I can trigger the crash, but
sadly "ftrace_notrace=msm_read" also crashes.

So there's more than one problem area.

What about ftrace_notrace=m*

?

That too crashes.


Which compiler are you using and can you send me your config.

Config attached.

Compiler: aarch64-linux-gnu-gcc (Linaro GCC 6.3-2017.02) 6.3.1 20170109

I wonder if there's something screwing up with the way ftrace nops are
working on this board.

A couple things of note, 1) it works fine after boot up. 2) it crashes
in the initcall code, so it's not due to ftrace being enabled too early.

I'd like to see the full command line as well. I bet if you remove the
qcom,msm-uartdm from the command line, and had just ftrace=function, it
may also boot fine too. Can you try that?


Kernel command line: root=/dev/disk/by-partlabel/rootfs rw rootwait
ftrace=function ftrace_notrace=m* earlycon console=ttyMSM0,115200n8

qcom,msm-uartdm is not in command line, it is the earlycon. So without
earlycon(bootconsole), board boots fine as we discussed earlier.


Have you tried with earlycon and no ftrace things on the commandline?

  root=/dev/disk/by-partlabel/rootfs rw rootwait earlycon console=ttyMSM0,115200n8

If earlycon is causing problems, it sounds like this may be another case
of earlycon uart handing off to the uart driver and that failing because
something gets printed while the uart is transitioning from the earlycon
console to the kernel boot console. I recall the uart would trample on
itself in interesting ways.


Yes I have tried with only earlycon enabled and everything is fine. Issue is reproduced only with ftrace=function cmdline.

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