probes that access userspace

[Frank Ch. Eigler]

Hi -

On Fri, Oct 14, 2005 at 12:11:15PM -0700, Kevin Stafford wrote:
> >>[...]  If this is not possible, I think it would be useful to
> >>enhance the language such that a probe script could explicitly
> >>notify the translator of a user space pointer access [...]
> >>   
> >Perhaps.  Other than the system call interfaces, is this difficulty
> >likely to arise often elsewhere?
> >
> >[...] For user-level probes, there is no ambiguity: every
> >pointer dereference is in user space.
>
> Being that for user-level probes, every pointer dereference is in
> user space, I believe it is certain that this difficulty will arise
> elsewhere.

Perhaps I was being unclear.  The "difficulty" I was referring to was
the ambiguity in whether an ordinary or special dereference operation
is required for any given $var->field expression.  It is this
ambiguity that could be resolved by the user via a language extension,
and it is this ambiguity that does not exist for variables that show
up in user-level probes.


- FChE