Re: copy faults from user_string* functions

[Eric Wong <normalperson@yhbt.net>]

Eric Wong <normalperson@yhbt.net> wrote:
> "Frank Ch. Eigler" <fche@redhat.com> wrote:
> > normalperson wrote:
> > > Hi all, just to clarify, not all of these faults are user errors, right?
> > > I get these sometimes with some strings (constants, I think):
> > > ERROR: user string copy fault -14 at 000000000042f16c near identifier 'user_string_n' at $prefix/share/systemtap/tapset/uconversions.stp:120:10
> > > [...]
> > 
> > It can simply mean having some not-yet-paged-in data, which in the
> > spirit of non-interference, stap will not trigger a page fault for.
> > Please try error-catching constructs such as try{}catch{}, or
> > --skip-badvars to tolerate them.
> 
> --skip-badvars seems to work for me.

Oops, I was on the wrong machine and running an older branch with
--skip-badvars.  try{}catch{} was needed for the user_string_n issue
I was having, but that seems to work.

> Is there any optional way to get stap to trigger page faults to get
> that data?

I could restructure my code to pass integers instead of strings as
a workaround, but I'm trying my best to be lazy :>