tracefs_options_get_supported(3) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | EXAMPLE | FILES | SEE ALSO | AUTHOR | REPORTING BUGS | LICENSE | RESOURCES | COPYING | NOTES | COLOPHON

LIBTRACEFS(3)               libtracefs Manual              LIBTRACEFS(3)

NAME         top

       tracefs_options_get_supported, tracefs_option_is_supported,
       tracefs_options_get_enabled, tracefs_option_is_enabled,
       tracefs_option_mask_is_set, tracefs_option_id - Get and check
       ftrace options.

SYNOPSIS         top

       #include <tracefs.h>

       const struct tracefs_options_mask *tracefs_options_get_supported(struct tracefs_instance *instance);
       bool tracefs_option_is_supported(struct tracefs_instance *instance, enum tracefs_option_id id);
       const struct tracefs_options_mask *tracefs_options_get_enabled(struct tracefs_instance *instance);
       bool tracefs_option_is_enabled(struct tracefs_instance *instance, enum tracefs_option_id id);
       bool tracefs_option_mask_is_set(const struct tracefs_options_mask options, enum tracefs_option_id id);
       enum tracefs_option_id *tracefs_option_id(const char *name);

DESCRIPTION         top

       This set of APIs can be used to get and check current ftrace
       options. Supported ftrace options may depend on the kernel
       version and the kernel configuration.

       The tracefs_options_get_supported() function gets all ftrace
       options supported by the system in the given instance. If
       instance is NULL, supported options of the top trace instance are
       returned. The set of supported options is the same in all created
       trace instances, but may be different than the top trace
       instance.

       The *tracefs_option_is_supported()/ function checks if the option
       with given id is supported by the system in the given instance.
       If instance is NULL, the top trace instance is used. If an option
       is supported at the top trace instance, it it may not be
       supported in a created trace instance.

       The tracefs_options_get_enabled() function gets all ftrace
       options, currently enabled in the given instance. If instance is
       NULL, enabled options of the top trace instance are returned.

       The tracefs_option_is_enabled() function checks if the option
       with given id is enabled in the given instance. If instance is
       NULL, the top trace instance is used.

       The tracefs_option_mask_is_set() function checks if the bit,
       corresponding to the option with id is set in the options bitmask
       returned from tracefs_option_get_enabled() and
       tracefs_option_is_supported().

       The tracefs_option_id() converts an option name into its
       corresponding id, if it is found. This allows to find the option
       id to use in the other functions if only the name is known.

RETURN VALUE         top

       The tracefs_options_get_supported() and
       tracefs_options_get_enabled() functions, on success, return a
       pointer to the bitmask within the instance, or a global bitmask
       for the top level, or NULL in case of an error. As the returned
       bitmask is part of the instance structure (or a global variable)
       and must not be freed or modified.

       The tracefs_option_is_supported() and tracefs_option_is_enabled()
       functions return true if the option in supported / enabled, or
       false otherwise.

       The tracefs_option_mask_is_set() returns true if the
       corresponding option is set in the mask or false otherwise.

       The tracefs_option_id() returns the corresponding id defined by
       tracefs_options(3) from the given name. If the name can not be
       found, then TRACEFS_OPTION_INVALID is returned.

EXAMPLE         top

           #include <tracefs.h>
           ...
           const struct tracefs_options_mask *options;
           ...
           options = tracefs_options_get_supported(NULL);
           if (!options) {
                   /* Failed to get supported options */
           } else {
                   ...
           }
           ...
           options = tracefs_options_get_enabled(NULL);
           if (!options) {
                   /* Failed to get options, enabled in the top instance */
           } else {
                   ...
           }
           if (tracefs_options_mask_is_set(options, TRACEFS_OPTION_LATENCY_FORMAT)) {
                   ...
           }
           ...

           if (tracefs_option_is_supported(NULL, TRACEFS_OPTION_LATENCY_FORMAT)) {
                   /* Latency format option is supprted */
           }

           ...

           if (tracefs_option_is_enabled(NULL, TRACEFS_OPTION_STACKTRACE)) {
                   /* Stacktrace option is enabled in the top instance */
           }

FILES         top

           tracefs.h
                   Header file to include in order to have access to the library APIs.
           -ltracefs
                   Linker switch to add when building a program that uses the library.

SEE ALSO         top

       libtracefs(3), libtraceevent(3), trace-cmd(1)

AUTHOR         top

           Steven Rostedt <rostedt@goodmis.org[1]>
           Tzvetomir Stoyanov <tz.stoyanov@gmail.com[2]>

REPORTING BUGS         top

       Report bugs to <linux-trace-devel@vger.kernel.org[3]>

LICENSE         top

       libtracefs is Free Software licensed under the GNU LGPL 2.1

RESOURCES         top

       https://git.kernel.org/pub/scm/libs/libtrace/libtracefs.git/ 

COPYING         top

       Copyright (C) 2020 VMware, Inc. Free use of this software is
       granted under the terms of the GNU Public License (GPL).

NOTES         top

        1. rostedt@goodmis.org
           mailto:rostedt@goodmis.org

        2. tz.stoyanov@gmail.com
           mailto:tz.stoyanov@gmail.com

        3. linux-trace-devel@vger.kernel.org
           mailto:linux-trace-devel@vger.kernel.org

COLOPHON         top

       This page is part of the libtracefs (Linux kernel trace file
       system library) project.  Information about the project can be
       found at ⟨https://www.trace-cmd.org/⟩.  If you have a bug report
       for this manual page, see ⟨https://www.trace-cmd.org/⟩.  This
       page was obtained from the project's upstream Git repository
       ⟨https://git.kernel.org/pub/scm/libs/libtrace/libtracefs.git⟩ on
       2024-06-14.  (At that time, the date of the most recent commit
       that was found in the repository was 2024-05-17.)  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 man-pages@man7.org

libtracefs 1.7.0               12/22/2023                  LIBTRACEFS(3)