Kernel's commit b38feccd663b55ab07116208b68e1ffc7c3c7e78 removed the second argument from the system call. * man2/s390_runtime_instr.2 (.SH SYNOPSIS): Add the prototype for the version syscall available in Linux 4.4 onward. (.SH DESCRIPTION): Change the description of the signum parameter to the past tense, note that it is ignored since Linux 4.4. (.SH VERSIONS): Note that syscall has changed its prototype along with the reason of change. (.SH NOTES): Note that it's impossible to judge whether the signal delivery functionality has been successfully enabled by the successfulness of the return code. --- man2/s390_runtime_instr.2 | 20 ++++++++++++++++++-- 1 file changed, 18 insertions(+), 2 deletions(-) diff --git a/man2/s390_runtime_instr.2 b/man2/s390_runtime_instr.2 index f979692..178237f 100644 --- a/man2/s390_runtime_instr.2 +++ b/man2/s390_runtime_instr.2 @@ -30,7 +30,12 @@ s390_runtime_instr \- enable/disable s390 CPU run-time instrumentation .\" This heder never had been a part of uapi as of 4.15 .\" .B #include <asm/runtime_instr.h> .\" .PP +.\" The signum argument has been removed in v4.4-rc1~138^2 +/* From Linux 3.7 to Linux 4.3 */ .BI "int s390_runtime_instr(int " command ", int " signum "); +.PP +/* Since Linux 4.4 */ +.BI "int s390_runtime_instr(int " command ");" .fi .SH DESCRIPTION The @@ -48,10 +53,12 @@ argument controls whether run-time instrumentation is started .PP The .IR signum -argument specifies the number of a real-time signal. -The real-time signal is sent to the thread if the run-time instrumentation +argument was available up to Linux 4.3 and allowed specifying the number +of a real-time signal. +The real-time signal was sent to the thread if the run-time instrumentation buffer is full or if the run-time-instrumentation-halted interrupt occurred. +The argument is ignored from Linux 4.4 onwards and no signal is sent. .SH RETURN VALUE On success, .BR s390_runtime_instr () @@ -79,6 +86,10 @@ Allocating memory for the run-time instrumentation control block failed. The run-time instrumentation facility is not available. .SH VERSIONS This system call is available since Linux 3.7. +.PP +Starting with Linux 4.4, the system call has its second argument removed, +since "[t]he external interrupts for runtime instrumentation buffer-full +and runtime instrumentation halted are unused and have no current user." .SH CONFORMING TO This Linux-specific system call is available only on the s390 architecture. The run-time instrumentation facility is available beginning with System z EC12. @@ -92,6 +103,11 @@ Kernel's header contains the necessary declarations for using run-time instrumentation. Unfortunately, it hasn't been included as a part of Linux's UAPI as of Linux 4.15. +.PP +Beware that since the second argument ignored since Linux 4.4, and no error +is returned in case it is specified on these newer kernels, application +can't rely on the availability of the signal delivery functionality +(or at least check it by setting erroneous value in the second argument). .SH SEE ALSO .BR syscall (2), .BR signal (7) -- 2.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-s390" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
