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NAME | DESCRIPTION | OTHER AUTOMATION | SEE ALSO | COLOPHON |
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WARNING::DEBUGINFO(7stap) WARNING::DEBUGINFO(7stap)
warning::debuginfo - systemtap missing-debuginfo warnings
For many symbolic probing operations, systemtap needs DWARF
debuginfo for the relevant binaries. This often includes
resolving function/statement probes, or $context variables in
related handlers. DWARF debuginfo is created by the compiler when
using CFLAGS -g, and may be found in the original binaries built
during compilation, or may have been split into separate files.
The SYSTEMTAP_DEBUGINFO_PATH environment variable affects where
systemtap looks for these files.
If your operating system came from a distributor, check with them
if debuginfo packages or variants are available. If your
distributor does not have debuginfo-equipped binaries at all, you
may need to rebuild it.
Systemtap uses the elfutils library to process ELF/DWARF files.
The version of elfutils used by systemtap is the number after the
slash in the -V output:
% stap -V
Systemtap translator/driver (version 4.2/0.178, rpm 4.2-1.fc30)
Copyright (C) 2005-2019 Red Hat, Inc. and others
[...]
This indicates systemtap version 4.2 with elfutils version 0.178.
New enough versions of elfutils (0.178+) enable systemtap to auto‐
matically download correct debuginfo from servers run by you, your
organization, and/or someone on the public internet. Try:
% export DEBUGINFOD_URLS=https://debuginfod.elfutils.org/
% export DEBUGINFOD_PROGRESS=1 # for progress messages, if you like
and rerun systemtap. It might just work. If it doesn't, read on.
kernel debuginfo
For scripts that target the kernel, systemtap may search
for the vmlinux file created during its original build.
This is distinct from the boot-loader's compressed/stripped
vmlinuz file, and much larger. If you have a hand-built
kernel, make sure it was built with the CONFIG_DEBUG_INFO=y
option. Some Linux distributions may include several ker‐
nel variants, including a confusingly named kernel-debug
(an alternative kernel, with its own kernel-debug-debuginfo
package), which is not the same thing as the kernel-debug‐
info (DWARF data for the base kernel). The stap-prep pro‐
gram can help install the right set.
process debuginfo
For scripts that target user-space, systemtap may search
for debuginfo. If you have hand-built binaries, use
CFLAGS=-g -O2 to compile them.
minidebuginfo
On some systems, binaries may be compiled with a subset of
debuginfo useful for function tracing and backtraces. This
'Minidebuginfo' is a xz compressed section labeled .gnu_de‐
bugdata. Support for minidebuginfo relies on elfutils ver‐
sion 0.156 or later.
compressed debuginfo
On some systems, debuginfo may be available, but compressed
into .zdebug_* sections. Support for compressed debuginfo
relies on elfutils version 0.153 or later.
unnecessary debuginfo
In some cases, a script may be altered to avoid requiring
debuginfo. For example, as script that uses probe
syscall.* probes could try instead probe nd_syscall.*
(for non-DWARF syscall): these work similarly, and use more
intricate (fragile) tapset functions to extract system call
arguments. Another option is use of compiled-in instrumen‐
tation such as kernel tracepoints or user-space <sys/sdt.h>
markers in libraries or executables, which do not require
debuginfo. If debuginfo was required for resolving a com‐
plicated $var->foo->bar expression, it may be possible to
use @cast(var,"foo","foo.h")->foo->bar to synthesize debug‐
info for that type from a header file.
On some platforms, systemtap may advise what commands to run, in
order to download needed debuginfo. Another possibility is to in‐
voke systemtap with the --download-debuginfo flag, which uses
ABRT. The stap-prep script included with systemtap may be able to
download the appropriate kernel debuginfo. Another possibility is
to install and use a stap-server remote-compilation instance on a
machine on your network, where debuginfo and compilation resources
can be centralized. Try the stap --use-server option, in case
such a server is already running.
gcc(1),
stap(1),
stappaths(7),
stap-server(8),
stap-prep(1),
strip(1),
warning::symbols(7stap),
error::dwarf(7stap),
error::reporting(7stap),
error::contextvars(7stap),
debuginfod(8),
http://elfutils.org/ ,
https://sourceware.org/elfutils/Debuginfod.html ,
http://fedoraproject.org/wiki/Features/MiniDebugInfo
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
WARNING::DEBUGINFO(7stap)
Pages that refer to this page: error::dwarf(7stap), error::pass2(7stap), warning::buildid(7stap), warning::symbols(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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