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Re: Using kernel global variables


Mike Mason wrote:
David Wilder wrote:
It is my understanding if we want to access a kernel global variable in a tap script we must be in a context that is using the variable.

I believe the variable must be within the *scope* of the probed function. The function doesn't necessarily have to use the variable for it to be within scope. A global defined in the same file as the function is automatically within scope.


I don't think exported symbols are within a function's scope from SystemTap's perspective, though the function can see them. Perhaps the dwarf info doesn't allow for that.

Mike

Thanks for the clarification Mike.
Based on question I have received about global variables I think there is a need to access exported variables that are outside the scope of the probepoint. For example accessing a global in a begin or exit probe. What do you think of such a feature?
I suspect we would need a way to flag the stap compiler that we are referencing a exported global something like using ^var.




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