Re: [PATCH 3/3] ftrace: Add debug_dump trace to dump binary data from kernel to userspace

From: Frédéric Weisbecker
Date: Fri Nov 14 2008 - 08:25:20 EST


2008/11/14 Frédéric Weisbecker <fweisbec@xxxxxxxxx>:
> 2008/11/14 Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>:
>> +static int
>> +trace_seq_putmem(struct trace_seq *s, void *mem, size_t len)
>> +{
>> + if (len > ((PAGE_SIZE - 1) - s->len))
>> + return 0;
>> +
>> + memcpy(s->buffer + s->len, mem, len);
>> + s->len += len;
>> +
>> + return len;
>> +}
>
>
>
> I forgot to say that I like the idea of this tracer. That would be
> useful to dump some random datas from memory.
> But I would find it much more useful if I could choose whether the
> output is raw bytes or an hexadecimal drawing of the dump,
> pretty much like hexdump does. That's better to know where we are in
> the dump, and to have a directly human readable dump.
>
> Currently this is not yet possible to choose whether we want a kind of
> output or one other. Or perhaps by listen to the iter flags.
> I will probably send a patch to make a tracer able to support custom
> flags through the old-named iter_ctrl file.


Actually yes, what you could do is verifying whether the current
trace_flags is TRACE_ITER_HEX or
TRACE_ITER_BIN and format your output depending on which one is set....
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