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NAME | DESCRIPTION | GATHERING MORE INFORMATION | SEE ALSO | COLOPHON |
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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 2025-02-02. (At that
time, the date of the most recent commit that was found in the
repository was 2025-01-28.) 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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HTML rendering created 2025-02-02 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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