Re: [PATCH v10 08/10] dyndbg: add print-to-tracefs, selftest with it - RFC

Vincent Whitchurch
2021-11-25T13:53:25Z

On Fri, Nov 19, 2021 at 11:46:31PM +0100, jim.cromie@gmail.com wrote:
> Vincent's code has the macro magic to define that event, which IIUC
> is what makes it controllable by ftrace, and therefore acceptable in
> principle to Steve.
> Would there be any reason to expand his set of 2 events into dev_dbg,
> pr_debug etc varieties ?
> (ie any value to separating dev, !dev ?, maybe so
>
> Sean's code uses trace_array_printk primarily, which is EXPORTed,
> which is a virtue.
>
> Vincents code does
> +/*
> + * This code is heavily based on __ftrace_trace_stack().
> + *
> + * Allow 4 levels of nesting: normal, softirq, irq, NMI.
> + */
>
> to implement
>
> +static void dynamic_trace(const char *fmt, va_list args)
>
> Has this __ftrace_trace_stack() code been bundled into or hidden under
> a supported interface ?
>
> would it look anything like trace_array_printk() ?
>
> what problem is that code solving inside dynamic-debug.c ?

I'm not sure I fully understand all of your questions, but perhaps this
thread with Steven's reply to the first version of my patchset will