1libtraceevent(3) 2================ 3 4NAME 5---- 6tep_get_header_page_size, tep_get_header_timestamp_size, tep_is_old_format - 7Get the data stored in the header page, in kernel context. 8 9SYNOPSIS 10-------- 11[verse] 12-- 13*#include <event-parse.h>* 14 15int *tep_get_header_page_size*(struct tep_handle pass:[*]_tep_); 16int *tep_get_header_timestamp_size*(struct tep_handle pass:[*]_tep_); 17bool *tep_is_old_format*(struct tep_handle pass:[*]_tep_); 18-- 19DESCRIPTION 20----------- 21These functions retrieve information from kernel context, stored in tracefs 22events/header_page. Old kernels do not have header page info, so default values 23from user space context are used. 24 25The *tep_get_header_page_size()* function returns the size of a long integer, 26in kernel context. The _tep_ argument is trace event parser context. 27This information is retrieved from tracefs events/header_page, "commit" field. 28 29The *tep_get_header_timestamp_size()* function returns the size of timestamps, 30in kernel context. The _tep_ argument is trace event parser context. This 31information is retrieved from tracefs events/header_page, "timestamp" field. 32 33The *tep_is_old_format()* function returns true if the kernel predates 34the addition of events/header_page, otherwise it returns false. 35 36RETURN VALUE 37------------ 38The *tep_get_header_page_size()* function returns the size of a long integer, 39in bytes. 40 41The *tep_get_header_timestamp_size()* function returns the size of timestamps, 42in bytes. 43 44The *tep_is_old_format()* function returns true, if an old kernel is used to 45generate the tracing data, which has no event/header_page. If the kernel is new, 46or _tep_ is NULL, false is returned. 47 48EXAMPLE 49------- 50[source,c] 51-- 52#include <event-parse.h> 53... 54struct tep_handle *tep = tep_alloc(); 55... 56 int longsize; 57 int timesize; 58 bool old; 59 60 longsize = tep_get_header_page_size(tep); 61 timesize = tep_get_header_timestamp_size(tep); 62 old = tep_is_old_format(tep); 63 64 printf ("%s kernel is used to generate the tracing data.\n", 65 old?"Old":"New"); 66 printf("The size of a long integer is %d bytes.\n", longsize); 67 printf("The timestamps size is %d bytes.\n", timesize); 68... 69-- 70 71FILES 72----- 73[verse] 74-- 75*event-parse.h* 76 Header file to include in order to have access to the library APIs. 77*-ltraceevent* 78 Linker switch to add when building a program that uses the library. 79-- 80 81SEE ALSO 82-------- 83*libtraceevent*(3), *trace-cmd*(1) 84 85AUTHOR 86------ 87[verse] 88-- 89*Steven Rostedt* <[email protected]>, author of *libtraceevent*. 90*Tzvetomir Stoyanov* <[email protected]>, author of this man page. 91-- 92REPORTING BUGS 93-------------- 94Report bugs to <[email protected]> 95 96LICENSE 97------- 98libtraceevent is Free Software licensed under the GNU LGPL 2.1 99 100RESOURCES 101--------- 102https://git.kernel.org/pub/scm/libs/libtrace/libtraceevent.git/ 103