Messages in this thread | | | Date | Mon, 14 Sep 2009 22:52:51 +0200 | From | Frederic Weisbecker <> | Subject | Re: [PATCH tracing/kprobes 0/7] tracing/kprobes: kprobe-based event tracer update and perf support |
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On Mon, Sep 14, 2009 at 01:16:13PM -0400, Masami Hiramatsu wrote: > 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 >
Yeah looks good!
>> 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))").
Well, that may be too much complexity. I guess if we want multi level dereference, say you want a->b->c it should be sufficient to probe the point where b->c gets it's value (if any).
But it would be nice to fetch a range: sa[begin:end] Or at least just giving the length of the range.
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