Re: Crash in msm serial on dragonboard with ftrace bootargs

[Sai Prakash Ranjan]

On 10/19/2018 7:21 PM, Steven Rostedt wrote:
> On Fri, 19 Oct 2018 12:24:05 +0530
> Sai Prakash Ranjan <saiprakash.ranjan@xxxxxxxxxxxxxx> wrote:
>
> > > > Anyone see any problems here?
> > >
> > > This seems sane to me, he says in the other thread that he put 'notrace' to
> > > the msm serial functions (which AIUI should prevent ftrace instrumentation)
> > > and he still sees the issue.
> > >    
> >
> > Yes I did add notrace to all functions in msm serial and checked the
> > objdump to make sure that those were not instrumented, and yet the
> > target crashed. This doesnt seem like an issue with ftrace but rather
> > with msm early con.
>
> The thing that still bothers me is that it boots fine without ftrace
> running, and that it requires tracing something to cause the problem.
> This tells me that ftrace has something to do with it. Perhaps it's
> just changing the timing.

Yes tracing does cause issue but only if earlycon is present. If I 
disable earlycon, then even tracing wont cause any issue and target 
boots fine.

> You said that if you add 'ftrace_filter=msm_read' to the command line,
> it still crashes?
>
> So only tracing that function we have an issue, right?

Tracing msm_read does cause the crash, but that is not the only one 
causing the crash because even after "ftrace_notrace=msm_read" the board 
crashes which is why I suspect msm earlycon and not ftrace.

Thanks,
Sai
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