LIBTRACEEVENT(3)             libtraceevent Manual             LIBTRACEEVENT(3)

NAME
       tep_get_header_page_size, tep_get_header_timestamp_size,
       tep_is_old_format - Get the data stored in the header page, in kernel
       context.

SYNOPSIS
       #include <event-parse.h>

       int tep_get_header_page_size(struct tep_handle *tep);
       int tep_get_header_timestamp_size(struct tep_handle *tep);
       bool tep_is_old_format(struct tep_handle *tep);

DESCRIPTION
       These functions retrieve information from kernel context, stored in
       tracefs events/header_page. Old kernels do not have header page info,
       so default values from user space context are used.

       The tep_get_header_page_size() function returns the size of a long
       integer, in kernel context. The tep argument is trace event parser
       context. This information is retrieved from tracefs events/header_page,
       "commit" field.

       The tep_get_header_timestamp_size() function returns the size of
       timestamps, in kernel context. The tep argument is trace event parser
       context. This information is retrieved from tracefs events/header_page,
       "timestamp" field.

       The tep_is_old_format() function returns true if the kernel predates
       the addition of events/header_page, otherwise it returns false.

RETURN VALUE
       The tep_get_header_page_size() function returns the size of a long
       integer, in bytes.

       The tep_get_header_timestamp_size() function returns the size of
       timestamps, in bytes.

       The tep_is_old_format() function returns true, if an old kernel is used
       to generate the tracing data, which has no event/header_page. If the
       kernel is new, or tep is NULL, false is returned.

EXAMPLE
           #include <event-parse.h>
           ...
           struct tep_handle *tep = tep_alloc();
           ...
                   int longsize;
                   int timesize;
                   bool old;

                   longsize = tep_get_header_page_size(tep);
                   timesize = tep_get_header_timestamp_size(tep);
                   old = tep_is_old_format(tep);

                   printf ("%s kernel is used to generate the tracing data.\n",
                           old?"Old":"New");
                   printf("The size of a long integer is %d bytes.\n", longsize);
                   printf("The timestamps size is %d bytes.\n", timesize);
           ...

FILES
           event-parse.h
                   Header file to include in order to have access to the library APIs.
           -ltraceevent
                   Linker switch to add when building a program that uses the library.

SEE ALSO
       libtraceevent(3), trace-cmd(1)

AUTHOR
           Steven Rostedt <rostedt@goodmis.org[1]>, author of libtraceevent.
           Tzvetomir Stoyanov <tz.stoyanov@gmail.com[2]>, author of this man page.

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

LICENSE
       libtraceevent is Free Software licensed under the GNU LGPL 2.1

RESOURCES
       https://git.kernel.org/pub/scm/libs/libtrace/libtraceevent.git/

NOTES
        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

libtraceevent                     01/13/2024                  LIBTRACEEVENT(3)