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RE: tcp.setsockopt probe seems to be returning incorrect optval
David Smith wrote on 25 March 2010 16:38:
> Since the tcp.setsockopt probe doesn't provide an 'optval', it
defaults to 0. That's why it always looks false.
Ah. I was playing with both $optval and optval, but I thought systemtap
would either die if I asked it for a value that wasn't provided, or just
resolve non built-in values to kernel variables. Thanks for the heads
up.
> You can print the value of $optval, but that's an user address, not a
value.
Aye I noticed.
> Assuming you only want to support options that have integer values,
this should work:
> user_int($optval)) }
Thanks David, that was exactly what I needed.
Oddly, user_int isn't covered by the RHEL 5.4 Language Reference, though
user_string is - looks like the doc didn't get updated for the SystemTap
0.7 release.
I'll update the warstory & share the love.
Mike
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