How to dump trace buffer at boot stage

[wyang]

Hi guys,

I ran into a issue that the msleep(10) does not return promptly at boot
stage, kernel would take amount of time to boot up. since I wanna trace
timer at boot stage,
so I enabled a trace event via command line such as
"trace_event=timer:*", but unfortunately the kernel did not boot
successfully, so is there any method to
dump the trace event to console while kernel cannot boot up sucessfully?

Thanks
Wei
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[Steven Rostedt]

On Thu, 27 Mar 2014 14:14:44 +0800

Post by wyang
Hi guys,
I ran into a issue that the msleep(10) does not return promptly at boot
stage, kernel would take amount of time to boot up. since I wanna trace
timer at boot stage,
so I enabled a trace event via command line such as
"trace_event=timer:*", but unfortunately the kernel did not boot
successfully, so is there any method to
dump the trace event to console while kernel cannot boot up sucessfully?

Hi, I would have replied earlier, but I was traveling when you sent
this.

Can you modify the kernel? If so, you can add ftrace_dump(DUMP_ALL);
anywhere in the kernel. It will dump the ftrace buffer to console when
it is hit.

But this is a good reminder. I should add the function:dump filter
ability to the command line.

-- Steve
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[wyang]

Post by Steven Rostedt
On Thu, 27 Mar 2014 14:14:44 +0800

Post by wyang
Hi guys,
I ran into a issue that the msleep(10) does not return promptly at boot
stage, kernel would take amount of time to boot up. since I wanna trace
timer at boot stage,
so I enabled a trace event via command line such as
"trace_event=timer:*", but unfortunately the kernel did not boot
successfully, so is there any method to
dump the trace event to console while kernel cannot boot up sucessfully?

Hi, I would have replied earlier, but I was traveling when you sent
this.
Can you modify the kernel? If so, you can add ftrace_dump(DUMP_ALL);
anywhere in the kernel. It will dump the ftrace buffer to console when
it is hit.

Steve,

Thanks for your response, I could modify my kernel, I would try it.
Thank you again.

Wei

Post by Steven Rostedt
But this is a good reminder. I should add the function:dump filter
ability to the command line.
-- Steve

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