Using kernel global variables

[David Wilder]

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.