Messages in this thread | | | Subject | Re: [RFC PATCH v2 0/1] of: easier debugging for node life cycle issues | From | Frank Rowand <> | Date | Thu, 25 Jan 2018 13:49:01 -0800 |
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Hi Wolfram,
On 01/25/18 03:03, Steven Rostedt wrote: > On Wed, 24 Jan 2018 22:55:13 -0800 > Frank Rowand <frowand.list@gmail.com> wrote: > >> Hi Steve, > >> >> Off the top of your head, can you tell me know early in the boot >> process a trace_event can be called and successfully provide the >> data to someone trying to debug early boot issues? > > The trace events are enabled by early_initcall().
< snip >
This means that ftrace can not be used for the of_node_get(), of_node_put(), and of_node_release() debug info, because these functions are called before early_initcall(). Please use pr_debug() for these functions.
As far as I know, the of_reconfig_notify() could remain an ftrace instrumented function. But now that the only thing that would be ftrace instrumented is of_reconfig_notify(), I don't see a strong justification for changing the existing pr_debug() calls to an ftrace alternative. Though I suspect the original author of the patch still might desire to have the "#ifdef DEBUG" surrounding the pr_debug() calls removed since one of his issues was having to recompile his kernel to do his debugging.
-Frank
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