From mboxrd@z Thu Jan  1 00:00:00 1970
From: Yang Shi <yang.shi@windriver.com>
Subject: Re: 4.8.6-rt5 ftrace function_graph hangs
Date: Fri, 2 Dec 2016 13:42:06 -0800
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Cc: Steven Rostedt <rostedt@goodmis.org>, <tglx@linutronix.de>,
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To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
        He Zhe <zhe.he@windriver.com>
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On 11/28/2016 6:33 AM, Sebastian Andrzej Siewior wrote:
> On 2016-11-21 16:30:40 [+0800], He Zhe wrote:
>> And I've tried on "a7fac75 Linux 4.8.1" and the latest linux-4.8.y-rt-rebase branch.They have the same issue.
> It works here. I tried your config with oldconfig on a x86-64 box. Do
> you have a x86-64 config?

Hi Sebastian,

Thanks for following up. I had been distracted by something else. And, I 
did more testing, then I narrowed it down to ARM and PPC only.

In addition, I narrowed it down to CONFIG_DEBUG_PREEMPT. function_graph 
tracer works well with it disabled on ARM and PPC. But, I haven't got 
time to figure out why.

Yang

>
>> Zhe
> Sebastian