NAME
warning::debuginfo - systemtap missing-debuginfo warnings DESCRIPTION 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 SYSTEMTAPDEBUGINFOPATH 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 2.3/0.156, rpm 2.3-1.fc19)
Copyright (C) 2005-2014 Red Hat, Inc. and others [...] This indicates systemtap version 2.3 with elfutils version 0.156. kernel debuginfo 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 CONFIGDEBUGINFO=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. process debuginfo
For scripts that target user-space, systemtap may search for de‐
buginfo. 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 de‐ buginfo useful for function tracing and backtraces. This 'Minidebuginfo' is a xz compressed section labeled .gnudebugda‐ ta. Support for minidebuginfo relies on elfutils version 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 debug‐ info. For example, as script that uses probe syscall.* probes
could try instead probe ndsyscall.* (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
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. AUTOMATION 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. The stap-prep script included with systemtap may be able to download the appropriate kernel debugin‐
fo. 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. SEE ALSO 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), http://elfutils.org/, http://fedoraproject.org/wiki/Features/MiniDebugInfo WARNING::DEBUGINFO(7stap)