warning::debuginfo - systemtap missing-debuginfo warnings
For many symbolic probing operations, systemtap needs DWARF debuginfo
for the relevant binaries. This often includes resolving func‐
tion/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
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 automati‐
cally download correct debuginfo from servers run by you, your organi‐
zation, 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.
For scripts that target the kernel, systemtap may search for the
vmlinux file created during its original build. This is dis‐
tinct 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 dis‐
tributions may include several kernel variants, including a con‐
fusingly 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.
For scripts that target user-space, systemtap may search for de‐
buginfo. If you have hand-built binaries, use CFLAGS=-g -O2 to
On some systems, binaries may be compiled with a subset of de‐
buginfo useful for function tracing and backtraces. This
'Minidebuginfo' is a xz compressed section labeled .gnu_debugda‐
ta. Support for minidebuginfo relies on elfutils version 0.156
On some systems, debuginfo may be available, but compressed into
.zdebug_* sections. Support for compressed debuginfo relies on
elfutils version 0.153 or later.
In some cases, a script may be altered to avoid requiring debug‐
info. 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 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
resolving a complicated $var->foo->bar expression, it may be
possible to use @cast(var,"foo","foo.h")->foo->bar to synthesize
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 system‐
tap 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.