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Re: [PATCH,resubmit] Add static probes to runtime linker
>>>>> "Roland" == Roland McGrath <roland@hack.frob.com> writes:
Paul> Lastly, could this interface be evolved? I don't know if system tap
Paul> probes already have a mechanism for versioned interface. If they do,
Paul> great. If not, the interface should probably include version number
Paul> somewhere.
Roland> There is no particular versioning mechanism and I'm not aware of any
Roland> plan for the issue having been proposed.
FWIW, I think there is already sufficient capability for consumers to
adapt to changes. Here are some observations -- I wouldn't really call
them recommendations, since I think some of these scenarios are best
avoided if there are other alternatives:
* It is compatible to add an argument to a probe.
* It is compatible to change the meaning of an argument to a probe,
provided that arguments are added at the same time. In this situation
a consumer can examine the number of arguments to decide what to do.
* It is not ok to reorder the arguments.
* It is only ok to drop an argument if no previous release of the
package had a probe with that number of arguments.
In effect the number of arguments is the probe version number.
* It is always ok to drop a probe and replace it with a new probe of a
different name. Consumers can be adaptive.
Tom