1*287e80b3SSadaf Ebrahimilibtracefs(3) 2*287e80b3SSadaf Ebrahimi============= 3*287e80b3SSadaf Ebrahimi 4*287e80b3SSadaf EbrahimiNAME 5*287e80b3SSadaf Ebrahimi---- 6*287e80b3SSadaf Ebrahimitracefs_cpu_open, tracefs_cpu_close, tracefs_cpu_alloc_fd, tracefs_cpu_free_fd - Opening trace_pipe_raw data for reading 7*287e80b3SSadaf Ebrahimi 8*287e80b3SSadaf EbrahimiSYNOPSIS 9*287e80b3SSadaf Ebrahimi-------- 10*287e80b3SSadaf Ebrahimi[verse] 11*287e80b3SSadaf Ebrahimi-- 12*287e80b3SSadaf Ebrahimi*#include <tracefs.h>* 13*287e80b3SSadaf Ebrahimi 14*287e80b3SSadaf Ebrahimistruct tracefs_cpu pass:[*]*tracefs_cpu_open*(struct tracefs_instance pass:[*]_instance_, 15*287e80b3SSadaf Ebrahimi int _cpu_, bool _nonblock_); 16*287e80b3SSadaf Ebrahimivoid *tracefs_cpu_close*(struct tracefs_cpu pass:[*]_tcpu_); 17*287e80b3SSadaf Ebrahimi 18*287e80b3SSadaf Ebrahimistruct tracefs_cpu pass:[*]*tracefs_cpu_alloc_fd*(int _fd_, int _subbuf_size_, bool _nonblock_); 19*287e80b3SSadaf Ebrahimivoid *tracefs_cpu_free_fd*(struct tracefs_cpu pass:[*]_tcpu_); 20*287e80b3SSadaf Ebrahimi-- 21*287e80b3SSadaf Ebrahimi 22*287e80b3SSadaf EbrahimiDESCRIPTION 23*287e80b3SSadaf Ebrahimi----------- 24*287e80b3SSadaf EbrahimiThis set of APIs can be used to open the raw data from the trace_pipe_raw 25*287e80b3SSadaf Ebrahimifiles in the tracefs file system in oder to read them with the *tracefs_cpu_read*(3) 26*287e80b3SSadaf Ebrahimifunctions. 27*287e80b3SSadaf Ebrahimi 28*287e80b3SSadaf EbrahimiThe *tracefs_cpu_open()* creates a descriptor that can read the tracefs 29*287e80b3SSadaf Ebrahimitrace_pipe_raw file for a given _cpu_ in a given _instance_. If _instance_ is 30*287e80b3SSadaf EbrahimiNULL than the toplevel trace_pipe_raw file is used. 31*287e80b3SSadaf Ebrahimi 32*287e80b3SSadaf EbrahimiThe *tracefs_cpu_close()* closes all the file descriptors associated to the trace_pipe_raw 33*287e80b3SSadaf Ebrahimiopened by *tracefs_cpu_open()*. 34*287e80b3SSadaf Ebrahimi 35*287e80b3SSadaf EbrahimiThe *tracefs_cpu_alloc_fd()* will create a tracefs_cpu descriptor from an existing 36*287e80b3SSadaf Ebrahimifile descriptor _fd_. This is useful to use when connecting to a socket or pipe where 37*287e80b3SSadaf Ebrahimithe other end is feeding raw tracing data in the same format as the trace_pipe_raw 38*287e80b3SSadaf Ebrahimifile would (like in guest to host tracing). The caller is responsible for determining 39*287e80b3SSadaf Ebrahimithe _subbuf_size_ that will be used to break up the sub-buffers being read by the 40*287e80b3SSadaf Ebrahimifile descriptor. The _nonblock_ is treated the same as the same parameter in 41*287e80b3SSadaf Ebrahimi*tracefs_cpu_open()*. 42*287e80b3SSadaf Ebrahimi 43*287e80b3SSadaf EbrahimiThe *tracefs_cpu_free_fd()* is used to free the descriptor returned by *tracefs_cpu_alloc_fd()*. 44*287e80b3SSadaf EbrahimiIt does all the clean up that *tracefs_cpu_close()* performs, and that could also be 45*287e80b3SSadaf Ebrahimiused to free up the descriptor created by *tracefs_cpu_alloc_fd()* but will also close 46*287e80b3SSadaf Ebrahimithe file descriptor passed in. Note that *tracefs_cpu_free_fd()* should not be used 47*287e80b3SSadaf Ebrahimion the descriptor returned by *tracefs_cpu_open()* as it will not close the file descriptor 48*287e80b3SSadaf Ebrahimicreated by it. 49*287e80b3SSadaf Ebrahimi 50*287e80b3SSadaf EbrahimiRETURN VALUE 51*287e80b3SSadaf Ebrahimi------------ 52*287e80b3SSadaf EbrahimiThe *tracefs_cpu_open()* returns a struct tracefs_cpu descriptor that can be 53*287e80b3SSadaf Ebrahimiused by the other functions or NULL on error. 54*287e80b3SSadaf Ebrahimi 55*287e80b3SSadaf EbrahimiThe *tracefs_cpu_alloc_fd()* returns a struct tracefs_cpu descriptor that can 56*287e80b3SSadaf Ebrahimibe used by the *tracefs_cpu_read*(3) related functions, where the descriptor 57*287e80b3SSadaf Ebrahimiwill be reading the passed in _fd_ file descriptor. 58*287e80b3SSadaf Ebrahimi 59*287e80b3SSadaf EbrahimiEXAMPLE 60*287e80b3SSadaf Ebrahimi------- 61*287e80b3SSadaf EbrahimiSee *tracefs_cpu_read*(3) for an example. 62*287e80b3SSadaf Ebrahimi 63*287e80b3SSadaf EbrahimiFILES 64*287e80b3SSadaf Ebrahimi----- 65*287e80b3SSadaf Ebrahimi[verse] 66*287e80b3SSadaf Ebrahimi-- 67*287e80b3SSadaf Ebrahimi*tracefs.h* 68*287e80b3SSadaf Ebrahimi Header file to include in order to have access to the library APIs. 69*287e80b3SSadaf Ebrahimi*-ltracefs* 70*287e80b3SSadaf Ebrahimi Linker switch to add when building a program that uses the library. 71*287e80b3SSadaf Ebrahimi-- 72*287e80b3SSadaf Ebrahimi 73*287e80b3SSadaf EbrahimiSEE ALSO 74*287e80b3SSadaf Ebrahimi-------- 75*287e80b3SSadaf Ebrahimi*libtracefs*(3), 76*287e80b3SSadaf Ebrahimi*libtraceevent*(3), 77*287e80b3SSadaf Ebrahimi*trace-cmd*(1) 78*287e80b3SSadaf Ebrahimi 79*287e80b3SSadaf EbrahimiAUTHOR 80*287e80b3SSadaf Ebrahimi------ 81*287e80b3SSadaf Ebrahimi[verse] 82*287e80b3SSadaf Ebrahimi-- 83*287e80b3SSadaf Ebrahimi*Steven Rostedt* <[email protected]> 84*287e80b3SSadaf Ebrahimi-- 85*287e80b3SSadaf EbrahimiREPORTING BUGS 86*287e80b3SSadaf Ebrahimi-------------- 87*287e80b3SSadaf EbrahimiReport bugs to <[email protected]> 88*287e80b3SSadaf Ebrahimi 89*287e80b3SSadaf EbrahimiLICENSE 90*287e80b3SSadaf Ebrahimi------- 91*287e80b3SSadaf Ebrahimilibtracefs is Free Software licensed under the GNU LGPL 2.1 92*287e80b3SSadaf Ebrahimi 93*287e80b3SSadaf EbrahimiRESOURCES 94*287e80b3SSadaf Ebrahimi--------- 95*287e80b3SSadaf Ebrahimihttps://git.kernel.org/pub/scm/libs/libtrace/libtracefs.git/ 96*287e80b3SSadaf Ebrahimi 97*287e80b3SSadaf EbrahimiCOPYING 98*287e80b3SSadaf Ebrahimi------- 99*287e80b3SSadaf EbrahimiCopyright \(C) 2022 Google, Inc. Free use of this software is granted under 100*287e80b3SSadaf Ebrahimithe terms of the GNU Public License (GPL). 101