Re: Why does $$parms show value as "?"

[Grant Edwards <grant dot b dot edwards at gmail dot com>]

On 2011-08-26, Frank Ch. Eigler <fche@redhat.com> wrote:
>
> grant.b.edwards wrote:
>
>> [...]
>>> and that should keep all variables around for your
>>> perusal.  Or it may be enough just to mark that function noinline.
>>
>> Declaring the function with the "noinline" keyword fixed the problem,
>> but turning down optimization is probably going to be needed as well
>> for other probes.
>
> See also http://sourceware.org/systemtap/wiki/TipContextVariables
> and https://bugzilla.redhat.com/show_bug.cgi?id=677681

Thanks, those are quite helpful (especially the first one).  Once I
prevented gcc from inlining the function, I could print out everything
I needed (once I figured out out to use @cast() inside a function to
which I passed the parameter).  Once I could print out the fields in
the skb structs, it didn't take too long to identify my bug and fix
it.  For me this is the first time systemtap has been "used in anger"
and it proved quite handy.

-- 
Grant Edwards               grant.b.edwards        Yow! I'm definitely not
                                  at               in Omaha!
                              gmail.com