Re: [PATCH tracing/kprobes 0/7] tracing/kprobes: kprobe-based eventtracer update and perf support

[Masami Hiramatsu]

Frederic Weisbecker wrote:
> On Fri, Sep 11, 2009 at 12:03:30PM -0400, Masami Hiramatsu wrote:
> > Frederic Weisbecker wrote:
> > > May be another step in the todo-list that would be nice: define the format
> > > for a type. Like it's done from ftrace events.
> >
> > Thanks!
> >
> > BTW, I'm not sure what the type means. Each event already has its own
> > event ID and event_call. Could you tell me which part of ftrace I should
> > refer to ?
>
>
> Actually I meant the format for a field.
> Say you define filename=arg1, it would be nice to have
>
> 	print "%s", filename
>
> in the format file.

Ah, indeed. It is better to support 'type' casting for each argument.
I think type casting can be done as below syntax.

NAME=ARG:TYPE
e.g.
jiffies64=@jiffies64:u64
message=%ax:str

> Hmm, now that I think about it, we can't dereference an array...for now :-)

:-)
BTW, currently, an entry of the array can be shown, e.g. +10(sa).
Hmm, for more complex dereference(e.g. accessing a->b[a->c]), it might need
another dereferencing syntax(e.g. "sa[16][sa[8]]"), or
just allow to use braces(e.g. "+(+8(sa))(+16(sa))").

Thank you,

--
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division

e-mail: mhiramat@xxxxxxxxxx

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