s390_runtime_instr(2) - Linux manual page (original) (raw)

s390runtimeinstr(2) System Calls Manual s390runtimeinstr(2)

NAME top

   s390_runtime_instr - enable/disable s390 CPU run-time
   instrumentation

LIBRARY top

   Standard C library (_libc_, _-lc_)

SYNOPSIS top

   **#include <asm/runtime_instr.h>** /* Definition of **S390_*** constants */
   **#include <sys/syscall.h>** /* Definition of **SYS_*** constants */
   **#include <unistd.h>**

   **int syscall(SYS_s390_runtime_instr, int** _command_**, int** _signum_**);**

   _Note_: glibc provides no wrapper for **s390_runtime_instr**(),
   necessitating the use of [syscall(2)](../man2/syscall.2.html).

DESCRIPTION top

   The **s390_runtime_instr**() system call starts or stops CPU run-time
   instrumentation for the calling thread.

   The _command_ argument controls whether run-time instrumentation is
   started (**S390_RUNTIME_INSTR_START**, 1) or stopped
   (**S390_RUNTIME_INSTR_STOP**, 2) for the calling thread.

   The _signum_ argument specifies the number of a real-time signal.
   This argument was used to specify a signal number that should be
   delivered to the thread if the run-time instrumentation buffer was
   full or if the run-time-instrumentation-halted interrupt had
   occurred.  This feature was never used, and in Linux 4.4 support
   for this feature was removed; thus, in current kernels, this
   argument is ignored.

RETURN VALUE top

   On success, **s390_runtime_instr**() returns 0 and enables the thread
   for run-time instrumentation by assigning the thread a default
   run-time instrumentation control block.  The caller can then read
   and modify the control block and start the run-time
   instrumentation.  On error, -1 is returned and _[errno](../man3/errno.3.html)_ is set to
   indicate the error.

ERRORS top

   **EINVAL** The value specified in _command_ is not a valid command.

   **EINVAL** The value specified in _signum_ is not a real-time signal
          number.  From Linux 4.4 onwards, the _signum_ argument has no
          effect, so that an invalid signal number will not result in
          an error.

   **ENOMEM** Allocating memory for the run-time instrumentation control
          block failed.

   **EOPNOTSUPP**
          The run-time instrumentation facility is not available.

STANDARDS top

   Linux on s390.

HISTORY top

   Linux 3.7.  System z EC12.

NOTES top

   The _asm/runtimeinstr.h_ header file is available since Linux 4.16.

   Starting with Linux 4.4, support for signalling was removed, as
   was the check whether _signum_ is a valid real-time signal.  For
   backwards compatibility with older kernels, it is recommended to
   pass a valid real-time signal number in _signum_ and install a
   handler for that signal.

SEE ALSO top

   [syscall(2)](../man2/syscall.2.html), [signal(7)](../man7/signal.7.html)

COLOPHON top

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Linux man-pages 6.10 2024-07-23 s390runtimeinstr(2)

Pages that refer to this page:syscalls(2)