Section: Misc. Reference Manual Pages (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
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
library to process ELF/DWARF files. The version of elfutils used by systemtap
is the number after the slash in the
% 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
file created during its original build. This is distinct from the
file, and much larger. If you have a hand-built kernel, make sure
it was built with the
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).
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
to compile them.
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 elfutils version 0.156 or later.
- compressed debuginfo
On some systems, debuginfo may be available, but compressed into
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
probes could try instead
(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
markers in libraries or executables, which do not require debuginfo.
If debuginfo was required for resolving a complicated
expression, it may be possible to use
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 systemtap
script included with systemtap may be able to download the
appropriate kernel debuginfo. Another possibility is to install and
remote-compilation instance on a machine on your network, where
debuginfo and compilation resources can be centralized. Try the
option, in case such a server is already running.