From: "Frank Ch. Eigler" <fche@redhat.com>
To: Kevin Stafford <kevinrs@us.ibm.com>
Cc: systemtap@sources.redhat.com
Subject: Re: probes that access userspace
Date: Fri, 14 Oct 2005 19:21:00 -0000 [thread overview]
Message-ID: <20051014192057.GB22281@redhat.com> (raw)
In-Reply-To: <435002D3.1050703@us.ibm.com>
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
next prev parent reply other threads:[~2005-10-14 19:21 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <E55D.2090005__29732.3145241991$1129302467$gmane$org@us.ibm.com>
2005-10-14 16:23 ` Frank Ch. Eigler
2005-10-14 19:10 ` Kevin Stafford
2005-10-14 19:21 ` Frank Ch. Eigler [this message]
2005-10-14 21:09 ` Jim Keniston
2005-10-14 22:15 ` Roland McGrath
2005-10-14 21:12 Kevin Stafford
-- strict thread matches above, loose matches on Subject: below --
2005-10-14 15:05 Kevin Stafford
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