Re: [PATCH V4 5/9] New probe type: DTrace USDT probes.

[Sergio Durigan Junior <sergiodj at redhat dot com>]

On Friday, August 07 2015, Joel Brobecker wrote:

>> So... we can make GDB to look at the DOF version and then use a
>> different struct (struct dof_provider_v1 ?) when handling embedded
>> programs using the old format.
>>
>> I can prepare a patch for this.  For testing purposes pdtrace can be
>> made to generate DOFv1 programs even in systems lacking an old enough
>> dtrace.

Thanks, Jose.  That would be much appreciated.

> Also, I didn't say it before, I wasn't so sure that casting a binary
> stream to a structure to read its contents was the best way to do
> things. It can of works, but makes the code a little harder to read,
> IMO, because accessing its contents requires the accessor macros.
> Perhaps it might be better to just have decoding routines that take
> the binary data and produce the corresponding struct, with the data
> properly decoded. That way, you can add DOF version checks and decode
> the data differently, without the rest of the code having to worry
> about which version of the type they should be using. It's not obvious
> to me that this way is better than the current way, but that's how
> I would have tried it first... (just my 2 cents)

I agree.  Something else really worth doing is creating a debug setting
for DTrace probes, and print useful information while decoding them.
Almost all (if not all) the information that Joel gathered using
external tools could have been printed from inside GDB.

Cheers,

-- 
Sergio
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