On Tue, 21 May 2019 09:33:17 -0400 Steven Rostedt <rostedt@xxxxxxxxxxx> wrote: > On Tue, 21 May 2019 16:56:16 +0900 > Masami Hiramatsu <mhiramat@xxxxxxxxxx> wrote: > > > Note that 'trace_event=' option enables trace event at very early > > timing, but the events added by 'kprobe_event=' are enabled right > > before enabling device drivers at this point. It is enough for > > tracing device driver initialization etc. > > Nice! > > I wonder if we can have this called before the trace_event boot is > analyzed. Then have the kprobe_event work more like the kprobe_events > file, and not enable the kprobes but only create them. If you want to > enable them you do a trace_event=kprobes as well. Yeah, I considered that, but there are several reasons to not to do that. - trace_event seems enabled very early point than kprobes itself.(but this can be fixable) - if user specifies kprobes at boot, he/she wants to enable that point at boot. - it is redundant to specify kprobe_event= and trace_event=, especially command line size is very limited. > Perhaps we could enable kprobes at early init? It should be possible, I will try to find what blocks it. I guess after we switch early_text_poke() to text_poke(), we can use kprobes on x86. But for other archs, I need to investigate more. > What do you think? Or is there something else in kprobes that prevents > such an early enabling of it? As I pointed above, I think we should enable it if user specify it. That's less typing :). Anyway I'll recheck early kprobe availablity. Thank you, -- Masami Hiramatsu <mhiramat@xxxxxxxxxx>
