Re: PR10746

[Josh Stone <jistone at redhat dot com>]

On 10/12/2009 12:45 PM, David Smith wrote:
> On 10/09/2009 11:42 PM, Wenji Huang wrote:
> > Hi,
> >
> > Commit "PR10746: improve error message on utrace-less kernels"
> > makes things strict for process.* on non-utrace kernel.  So
> > the following scripts will get error.
> >
> > $ stap -l 'process("./bz6905").statement("*")'
> > $ stap -p2 -e 'probe process.syscall{}'
> > $ stap -k -p3 -e 'probe process.begin{}'
> >
> > There is also no generated C file for those scripts when we
> > need code review.
> >
> > In fact, procedure 1-3 are not related to utrace.
>
> Actually, they all are related to utrace.
> [...]
> So, the above examples will not work without utrace.

I think Wenji's point is that up to pass-3 could be completed without 
any utrace support.

However, we shouldn't permit that.  Our probe resolution should only 
provide probe points that are actually usable on the target kernel, 
which means rejecting process.* for non-utrace kernels.  This is 
required to allow constructs like:

  probe process.syscall!, syscall.* { /*...*/ }


Josh