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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 au‐
tomatically 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 com‐
pressed/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 kernel 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-debuginfo (DWARF data for the base
kernel). The stap-prep program 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_debugdata. Support for minidebuginfo relies on elfu‐
tils version 0.156 or later.
compressed debuginfo
On some systems, debuginfo may be available, but com‐
pressed 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 sys‐
tem call arguments. Another option is use of compiled-in
instrumentation 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 re‐
solving a complicated $var->foo->bar expression, it may be
possible to use @cast(var,"foo","foo.h")->foo->bar to syn‐
thesize debuginfo 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
invoke 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 possibili‐
ty is to install and use a stap-server remote-compilation in‐
stance on a machine on your network, where debuginfo and compila‐
tion resources can be centralized. Try the stap --use-server op‐
tion, 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 [email protected].
This page was obtained from the project's upstream Git repository
⟨git://sourceware.org/git/systemtap.git⟩ on 2024-06-14. (At that
time, the date of the most recent commit that was found in the
repository was 2024-06-13.) 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
[email protected]
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 2024-06-26 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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