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ERROR::PASS2(7stap) ERROR::PASS2(7stap)
error::pass2 - systemtap pass-2 errors
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 continue.
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.
stap(1),
stap-prep(1),
stapprobes(3stap),
probe::*(3stap),
error::dwarf(7stap),
error::inode-uprobes(7stap),
warning::debuginfo(7stap),
error::reporting(7stap)
This page is part of the systemtap (a tracing and live-system
analysis tool) project. Information about the project can be
found at ⟨https://sourceware.org/systemtap/⟩. If you have a bug
report for this manual page, send it to systemtap@sourceware.org.
This page was obtained from the project's upstream Git repository
⟨git://sourceware.org/git/systemtap.git⟩ on 2022-12-17. (At that
time, the date of the most recent commit that was found in the
repository was 2022-12-16.) If you discover any rendering
problems in this HTML version of the page, or you believe there
is a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
man-pages@man7.org
ERROR::PASS2(7stap)
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