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Subject: Re: kernelshark plugins and ftrace array fields
From: Steven Rostedt <rostedt@goodmis.org>
To: Avi Kivity <avi@redhat.com>
Cc: linux-kernel <linux-kernel@vger.kernel.org>,
        KVM list <kvm@vger.kernel.org>
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Date: Thu, 02 Sep 2010 14:38:56 -0400
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On Thu, 2010-09-02 at 14:16 -0400, Steven Rostedt wrote:
> On Thu, 2010-09-02 at 17:34 +0300, Avi Kivity wrote:

> 
> OK, with no modification of what I have already, I just created this
> handler:
> 
> static int
> kvm_emulate_insn_handler(struct trace_seq *s, struct record *record,
>                          struct event_format *event, void *context)
> {
>         struct format_field *field;
>         unsigned char *data = record->data;
>         int i;
> 
>         field = pevent_find_field(event, "insn");
>         if (!field) {
>                 trace_seq_puts(s, "Can't find inst field");
>                 return 0;
>         }
> 
>         trace_seq_puts(s, "insn: ");
>         for (i = 0; i < field->size; i++) {
>                 trace_seq_printf(s, "%s%02x",
>                                  i ? "," : "",
>                                  data[field->offset + i]);
>         }
> 
>         return 0;
> }
> 
> 
> I think this is what you would want, right?

I think I will add a:

void *pevent_get_field_raw(stuct trace_seq *s,
			struct event_format *event, 
			char *field_name,
			struct record *record,
			int **field_len);

which will return a pointer into record->data and set the field_len to
the actual size.

This will be useful for dynamic arrays too, since it is more complex
than just using a field->offset.

-- Steve