Re: [RFC PATCH v2 00/15] tracing: of: Boot time tracing using devicetree

[Masami Hiramatsu <mhiramat@kernel.org>]

Hello,

I discussed with Frank and other kernel developers last week at OSSJ 2019.
Eventually, I decided to leave from devicetree, because it can unstabilize
current devicetree desgin and policy. Instead, aim to introduce a new
generic structured kernel cmdline, something like "configtree".

I thought JSON or other generic data format, but they look a bit bloated
for my purpose. I just need something like "extended hierarchical kernel
cmdline". For example,

ftrace {
  options = "sym-addr"
  events = "initcall:*"
  tp-printk
  event.0 {
    name = "tasl:task_newtask"
    filter = "pid < 128"
  } 
}

Which can be written as

ftrace.options="sym-addr" ftrace.events="initcall:*" ftrace.tp-printk ftrace.event.0.name="tasl:task_newtask" ftrace.event.0.filter="pid < 128"

on current kernel cmdline.

So, the parameters are linearly extended from current kernel cmdline.
Kernel internal APIs must be able to handle both of current cmdline
key-values and configtree key-values.

Thank you,

-- 
Masami Hiramatsu <mhiramat@kernel.org>