ERROR::PASS2(7stap)                                      ERROR::PASS2(7stap)

NAME         top

       error::pass2 - systemtap pass-2 errors

DESCRIPTION         top

       Errors that occur during pass 2 (elaboration) can have a variety of
       causes.  Common types include:

       missing debuginfo
              The script requires debuginfo to resolve a probe point, but
              could not find any.  See error::dwarf(7stap) and
              warning::debuginfo(7stap) for more details.

       unavailable probe point classes
              Some types of probe points are only available on certain
              system versions, architectures, and configurations.  For
              example, user-space process.*  probes may require utrace or
              uprobes capability in the kernel for this architecture.

       unavailable probe points
              Some probe points may be individually unavailable even when
              their class is fine.  For example, kprobe.function("foobar")
              may fail if function foobar does not exist in the kernel any
              more.  Debugging or symbol data may be absent for some types
              of .function or .statement probes; check for availability of
              debuginfo.  Try the stap-prep program to download possibly-
              required debuginfo.  Use a wildcard parameter such as stap -l
              'kprobe.function("*foo*")' to locate still-existing variants.
              Use ! or ?  probe point suffixes to denote optional /
              preferred-alternatives, to let the working parts of a script

       typos  There might be a spelling error in the probe point name
              ("sycsall" vs.  "syscall").  Wildcard probes may not find a
              match at all in the tapsets.  Recheck the names using stap -l
              PROBEPOINT.  Another common mistake is to use the .  operator
              instead of the correct -> when dereferencing context variable
              subfields or pointers: $foo->bar->baz even if in C one would
              say foo->bar.baz.

       unavailable context variables
              Systemtap scripts often wish to refer to variables from the
              context of the probed programs using $variable notation.
              These variables may not always be available, depending on
              versions of the compiler, debugging/optimization flags used,
              architecture, etc.  Use stap -L PROBEPOINT to list available
              context variables for given probes.  Use the @defined()
              expression to test for the resolvability of a context variable
              expression.  Consider using the stap --skip-badvars option to
              silently replace misbehaving context variable expressions with
              zero.  Experiment with the stap --prologue-searching option.

       module cache inconsistencies
              Occasionally, the systemtap module cache
              ($HOME/.systemtap/cache) might contain obsolete information
              from a prior system configuration/version, and produce false
              results as systemtap attempts to reuse it.  Retrying with stap
              --poison-cache ...  forces new information to be generated.
              Note: this should not happen and likely represents a systemtap
              bug.  Please report it.


       Increasing the verbosity of pass-2 with an option such as --vp 02 can
       help pinpoint the problem.

SEE ALSO         top


COLOPHON         top

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