xref: /qemu/docs/tools/qemu-trace-stap.rst (revision 605ffebb2e206d9dec746ceed0de7be561b7354b)

QEMU SystemTap trace tool
=========================

Synopsis
--------

**qemu-trace-stap** [*GLOBAL-OPTIONS*] *COMMAND* [*COMMAND-OPTIONS*] *ARGS*...

Description
-----------

The ``qemu-trace-stap`` program facilitates tracing of the execution
of QEMU emulators using SystemTap.

It is required to have the SystemTap runtime environment installed to use
this program, since it is a wrapper around execution of the ``stap``
program.

Options
-------

.. program:: qemu-trace-stap

The following global options may be used regardless of which command
is executed:

.. option:: --verbose, -v

  Display verbose information about command execution.

The following commands are valid:

.. option:: list BINARY PATTERN...

  List all the probe names provided by *BINARY* that match
  *PATTERN*.

  If *BINARY* is not an absolute path, it will be located by searching
  the directories listed in the ``$PATH`` environment variable.

  *PATTERN* is a plain string that is used to filter the results of
  this command. It may optionally contain a ``*`` wildcard to facilitate
  matching multiple probes without listing each one explicitly. Multiple
  *PATTERN* arguments may be given, causing listing of probes that match
  any of the listed names. If no *PATTERN* is given, the all possible
  probes will be listed.

  For example, to list all probes available in the ``qemu-system-x86_64``
  binary:

  ::

    $ qemu-trace-stap list qemu-system-x86_64

  To filter the list to only cover probes related to QEMU's cryptographic
  subsystem, in a binary outside ``$PATH``

  ::

    $ qemu-trace-stap list /opt/qemu/4.0.0/bin/qemu-system-x86_64 'qcrypto*'

.. option:: run OPTIONS BINARY PATTERN...

  Run a trace session, printing formatted output any time a process that is
  executing *BINARY* triggers a probe matching *PATTERN*.

  If *BINARY* is not an absolute path, it will be located by searching
  the directories listed in the ``$PATH`` environment variable.

  *PATTERN* is a plain string that matches a probe name shown by the
  *LIST* command. It may optionally contain a ``*`` wildcard to
  facilitate matching multiple probes without listing each one explicitly.
  Multiple *PATTERN* arguments may be given, causing all matching probes
  to be monitored. At least one *PATTERN* is required, since stap is not
  capable of tracing all known QEMU probes concurrently without overflowing
  its trace buffer.

  Invocation of this command does not need to be synchronized with
  invocation of the QEMU process(es). It will match probes on all
  existing running processes and all future launched processes,
  unless told to only monitor a specific process.

  Valid command specific options are:

  .. program:: qemu-trace-stap-run

  .. option:: --pid=PID, -p PID

    Restrict the tracing session so that it only triggers for the process
    identified by *PID*.

  For example, to monitor all processes executing ``qemu-system-x86_64``
  as found on ``$PATH``, displaying all I/O related probes:

  ::

    $ qemu-trace-stap run qemu-system-x86_64 'qio*'

  To monitor only the QEMU process with PID 1732

  ::

    $ qemu-trace-stap run --pid=1732 qemu-system-x86_64 'qio*'

  To monitor QEMU processes running an alternative binary outside of
  ``$PATH``, displaying verbose information about setup of the
  tracing environment:

  ::

    $ qemu-trace-stap -v run /opt/qemu/4.0.0/qemu-system-x86_64 'qio*'

See also
--------

:manpage:`qemu(1)`, :manpage:`stap(1)`

..
  Copyright (C) 2019 Red Hat, Inc.

  This program is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation; either version 2 of the License, or
  (at your option) any later version.