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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 2018-02-02. (At that
time, the date of the most recent commit that was found in the repos‐
itory was 2018-02-01.) 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 2018-02-02 by Michael Kerrisk, author of The Linux Programming Interface, maintainer of the Linux man-pages project. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH.
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