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| author | Michael Kerrisk <mtk.manpages@gmail.com> | 2007-06-25 09:24:48 +0000 |
|---|---|---|
| committer | Michael Kerrisk <mtk.manpages@gmail.com> | 2007-06-25 09:24:48 +0000 |
| commit | 5a5574b9b68f3d0277f618da2827d7e51f280f31 (patch) | |
| tree | 58d77a4debfd30e8cd9055743cb263cbb40a5d35 | |
| parent | f531acc327ac8f75137f960077a602526d5a5f92 (diff) | |
| download | man-pages-5a5574b9b68f3d0277f618da2827d7e51f280f31.tar.gz | |
Note SIGRTMIN value depends on glibc.
Various rewites and additions to the text in real-time signals.
| -rw-r--r-- | man7/signal.7 | 53 |
1 files changed, 40 insertions, 13 deletions
diff --git a/man7/signal.7 b/man7/signal.7 index 97fcc133fd..fe9798a3a7 100644 --- a/man7/signal.7 +++ b/man7/signal.7 @@ -97,7 +97,11 @@ A signal may be generated (and thus pending) for a process as a whole (e.g., when sent using .BR kill (2)) or for a specific thread (e.g., certain signals, -such as SIGSEGV and SIGFPE, generated as a +such as +.B SIGSEGV +and +.BR SIGFPE , +generated as a consequence of executing a specific machine-language instruction are thread directed, as are signals targeted at a specific thread using .BR pthread_kill (3)). @@ -163,7 +167,7 @@ ____ lB c c l. Signal Value Action Comment SIGBUS 10,7,10 Core Bus error (bad memory access) -SIGPOLL Term Pollable event (Sys V). Synonym of SIGIO +SIGPOLL Term Pollable event (Sys V). Synonym of \fISIGIO\fP SIGPROF 27,27,29 Term Profiling timer expired SIGSYS 12,\-,12 Core Bad argument to routine (SVr4) SIGTRAP 5 Core Trace/breakpoint trap @@ -190,16 +194,16 @@ l c c l ____ lB c c l. Signal Value Action Comment -SIGIOT 6 Core IOT trap. A synonym for SIGABRT +SIGIOT 6 Core IOT trap. A synonym for \fBSIGABRT\fP SIGEMT 7,\-,7 Term SIGSTKFLT \-,16,\- Term Stack fault on coprocessor (unused) SIGIO 23,29,22 Term I/O now possible (4.2BSD) -SIGCLD \-,\-,18 Ign A synonym for SIGCHLD +SIGCLD \-,\-,18 Ign A synonym for \fBSIGCHLD\fP SIGPWR 29,30,19 Term Power failure (System V) -SIGINFO 29,\-,\- A synonym for SIGPWR +SIGINFO 29,\-,\- A synonym for \fBSIGPWR\fP SIGLOST \-,\-,\- Term File lock lost SIGWINCH 28,28,20 Ign Window resize signal (4.3BSD, Sun) -SIGUNUSED \-,31,\- Term Unused signal (will be SIGSYS) +SIGUNUSED \-,31,\- Term Unused signal (will be \fBSIGSYS\fP) .TE (Signal 29 is @@ -226,13 +230,35 @@ on several other Unix systems. .SS "Real-time Signals" Linux supports real-time signals as originally defined in the POSIX.1b real-time extensions (and now included in POSIX.1-2001). -Linux supports 32 real-time signals, numbered from 32 -.RB ( SIGRTMIN ) -to 63 -.RB ( SIGRTMAX ). -(Programs should always refer to real-time signals using notation +The range of supported real-time signals is defined by the macros +.B SIGRTMIN +and +.BR SIGRTMAX . +POSIX.1-2001 requires that an implementation support at least +.B _POSIX_RTSIG_MAX +(8) real-time signals. +.PP +The Linux kernel supports a range of 32 different real-time +signals, numbered 33 to 64. +However, the glibc POSIX threads implementation internally uses +two (for NPTL) or three (for LinuxThreads) real-time signals +(see +.BR pthreads (7)), +and adjusts the value of +.B SIGRTMIN +suitably (to 34 or 35). +Because the range of available real-time signals varies according +to the glibc threading implementation (and this variation can occur +at run-time according to the available kernel and glibc), +and indeed the range of real-time signals varies across Unix systems, +programs should +.IR "never refer to real-time signals using hard-coded numbers" , +but instead should always refer to real-time signals using the notation .BR SIGRTMIN +n, -since the range of real-time signal numbers varies across Unix systems.) +and include suitable (run-time) checks that +.BR SIGRTMIN +n +does not exceed +.BR SIGRTMAX . .PP Unlike standard signals, real-time signals have no predefined meanings: the entire set of real-time signals can be used for application-defined @@ -282,7 +308,8 @@ Linux, like many other implementations, gives priority to standard signals in this case. .PP According to POSIX, an implementation should permit at least -_POSIX_SIGQUEUE_MAX (32) real-time signals to be queued to +.B _POSIX_SIGQUEUE_MAX +(32) real-time signals to be queued to a process. However, Linux does things differently. In kernels up to and including 2.6.7, Linux imposes |