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To: Matthew Ward <matthew.ward@fubra.com>
Cc: systemtap@sources.redhat.com
Subject: Re: usertap kernel read faults - can I ignore them somehow?
References: <jb2pmt$is5$1@dough.gmane.org>
From: fche@redhat.com (Frank Ch. Eigler)
Date: Tue, 29 Nov 2011 14:38:00 -0000
In-Reply-To: <jb2pmt$is5$1@dough.gmane.org> (Matthew Ward's message of "Tue, 29 Nov 2011 14:20:12 +0000")
Message-ID: <y0m8vmzvvsn.fsf@fche.csb>
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Hi, Matthew -

> I'm having an issue with our usertap tapset
> (https://github.com/fubralimited/usertap) [...]
> ERROR: kernel read fault at 0x0000000100000264 (addr) near identifier
> '@cast' at /usr/share/systemtap/tapset/ip.stp:45:11

You can do several things.
First, you can run "stap --skip-badvars ...", which turns all erroneous
$var accesses into 0.  Second, you can (sometimes) wrap expressions with
   try { var = $var } catch { } 
to absorb the error.  But see <http://sourceware.org/PR13306>.

- FChE