BSD 4_3_Net_2 release

[unix-history] / usr / src / lib / libc / sys / sigaction.2

diff --git a/usr/src/lib/libc/sys/sigaction.2 b/usr/src/lib/libc/sys/sigaction.2
index eec8fa1..13c2c50 100644 (file)
--- a/usr/src/lib/libc/sys/sigaction.2
+++ b/usr/src/lib/libc/sys/sigaction.2
@@ -1,73 +1,91 @@
 .\" Copyright (c) 1980, 1990 The Regents of the University of California.
 .\" All rights reserved.
 .\"
 .\" Copyright (c) 1980, 1990 The Regents of the University of California.
 .\" All rights reserved.
 .\"

-.\" %sccs.include.redist.man%
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\"    notice, this list of conditions and the following disclaimer.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\"    notice, this list of conditions and the following disclaimer in the
+.\"    documentation and/or other materials provided with the distribution.
+.\" 3. All advertising materials mentioning features or use of this software
+.\"    must display the following acknowledgement:
+.\"    This product includes software developed by the University of
+.\"    California, Berkeley and its contributors.
+.\" 4. Neither the name of the University nor the names of its contributors
+.\"    may be used to endorse or promote products derived from this software
+.\"    without specific prior written permission.

 .\"
 .\"

-.\"    @(#)sigaction.2 6.1 (Berkeley) %G%
+.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+.\" SUCH DAMAGE.

 .\"
 .\"

-.TH SIGACTION 2 ""
-.UC 7
-.ie t .ds d \(dg
-.el .ds d \z'|+'
-.ie t .ds p \(dd
-.el .ds p \z'|='
-.ie t .ds b \(bu
-.el .ds b @
-.SH NAME
-sigaction \- software signal facilities
-.SH SYNOPSIS
-.nf
-.B #include <signal.h>
-.PP
-.B struct sigaction {
-.B     void    (*sa_handler)();
-.B     sigset_t        sa_mask;
-.B     int     sa_flags;
-.B };
-.PP
-.B sigaction(sig, act, oact)
-.B int sig;
-.B struct sigaction *act, *oact;
-.fi
-.SH DESCRIPTION
+.\"    @(#)sigaction.2 6.3 (Berkeley) 7/23/91
+.\"
+.Dd July 23, 1991
+.Dt SIGACTION 2
+.Os
+.Sh NAME
+.Nm sigaction
+.Nd software signal facilities
+.Sh SYNOPSIS
+.Fd #include <signal.h>
+.Bd -literal
+struct sigaction {
+       void     (*sa_handler)();
+       sigset_t sa_mask;
+       int      sa_flags;
+};
+.Ed
+.Fn sigaction "int sig" "struct sigaction *act" "struct sigaction *oact"
+.Sh DESCRIPTION

 The system defines a set of signals that may be delivered to a process.
 Signal delivery resembles the occurence of a hardware interrupt:
 the signal is blocked from further occurrence, the current process 
 context is saved, and a new one is built.  A process may specify a
 The system defines a set of signals that may be delivered to a process.
 Signal delivery resembles the occurence of a hardware interrupt:
 the signal is blocked from further occurrence, the current process 
 context is saved, and a new one is built.  A process may specify a

-.I handler
+.Em handler

 to which a signal is delivered, or specify that a signal is to be 
 to which a signal is delivered, or specify that a signal is to be 

-.IR ignored .
+.Em ignored .

 A process may also specify that a default action is to be taken
 by the system when a signal occurs.
 A signal may also be
 A process may also specify that a default action is to be taken
 by the system when a signal occurs.
 A signal may also be

-.IR blocked ,
+.Em blocked ,

 in which case its delivery is postponed until it is
 in which case its delivery is postponed until it is

-.IR unblocked .
+.Em unblocked .

 The action to be taken on delivery is determined at the time
 of delivery.
 Normally, signal handlers execute on the current stack
 of the process.  This may be changed, on a per-handler basis,
 so that signals are taken on a special
 The action to be taken on delivery is determined at the time
 of delivery.
 Normally, signal handlers execute on the current stack
 of the process.  This may be changed, on a per-handler basis,
 so that signals are taken on a special

-.IR "signal stack" .
-.PP
+.Em "signal stack" .
+.Pp

 Signal routines execute with the signal that caused their
 invocation
 Signal routines execute with the signal that caused their
 invocation

-.IR blocked ,
+.Em blocked ,

 but other signals may yet occur.
 A global 
 but other signals may yet occur.
 A global 

-.I "signal mask"
+.Em "signal mask"

 defines the set of signals currently blocked from delivery
 to a process.  The signal mask for a process is initialized
 from that of its parent (normally empty).  It
 may be changed with a
 defines the set of signals currently blocked from delivery
 to a process.  The signal mask for a process is initialized
 from that of its parent (normally empty).  It
 may be changed with a

-.IR sigprocmask (2)
+.Xr sigprocmask 2

 call, or when a signal is delivered to the process.
 call, or when a signal is delivered to the process.

-.PP
+.Pp

 When a signal
 condition arises for a process, the signal is added to a set of
 signals pending for the process.
 If the signal is not currently
 When a signal
 condition arises for a process, the signal is added to a set of
 signals pending for the process.
 If the signal is not currently

-.I blocked
+.Em blocked

 by the process then it is delivered to the process.
 Signals may be delivered any time a process enters the operating system
 (e.g., during a system call, page fault or trap, or clock interrupt).
 by the process then it is delivered to the process.
 Signals may be delivered any time a process enters the operating system
 (e.g., during a system call, page fault or trap, or clock interrupt).


@@ -77,7 +95,7 @@ Additional signals may be processed at the same time, with each
 appearing to interrupt the handlers for the previous signals
 before their first instructions.
 The set of pending signals is returned by the
 appearing to interrupt the handlers for the previous signals
 before their first instructions.
 The set of pending signals is returned by the

-.IR sigpending (2)
+.Xr sigpending 2

 function.
 When a caught signal
 is delivered, the current state of the process is saved,
 function.
 When a caught signal
 is delivered, the current state of the process is saved,


@@ -88,243 +106,263 @@ normally the process will resume execution in the context
 from before the signal's delivery.
 If the process wishes to resume in a different context, then it
 must arrange to restore the previous context itself.
 from before the signal's delivery.
 If the process wishes to resume in a different context, then it
 must arrange to restore the previous context itself.

-.PP
+.Pp

 When a signal is delivered to a process a new signal mask is
 installed for the duration of the process' signal handler
 (or until a
 When a signal is delivered to a process a new signal mask is
 installed for the duration of the process' signal handler
 (or until a

-.I sigprocmask
+.Xr sigprocmask

 call is made).
 This mask is formed by taking the union of the current signal mask set,
 the signal to be delivered, and 
 the signal mask associated with the handler to be invoked.
 call is made).
 This mask is formed by taking the union of the current signal mask set,
 the signal to be delivered, and 
 the signal mask associated with the handler to be invoked.

-.PP
-.I Sigaction
+.Pp
+.Fn Sigaction

 assigns an action for a specific signal.
 If
 assigns an action for a specific signal.
 If

-.I act
+.Fa act

 is non-zero, it
 is non-zero, it

-specifies an action (SIG_DFL, SIG_IGN, or a handler routine) and mask
+specifies an action
+.Pf ( Dv SIG_DFL ,
+.Dv SIG_IGN ,
+or a handler routine) and mask

 to be used when delivering the specified signal.
 If 
 to be used when delivering the specified signal.
 If 

-.I oact
+.Fa oact

 is non-zero, the previous handling information for the signal
 is returned to the user.
 is non-zero, the previous handling information for the signal
 is returned to the user.

-.PP
+.Pp

 Once a signal handler is installed, it remains installed
 until another
 Once a signal handler is installed, it remains installed
 until another

-.I sigaction
+.Fn sigaction

 call is made, or an 
 call is made, or an 

-.IR execve (2)
+.Xr execve 2

 is performed.
 is performed.

-The default action for a signal may be reinstated by setting
-.I sa_handler
-to SIG_DFL.
-The default actions are termination, possibly with a core image;
+A signal-specific default action may be reset by
+setting
+.Fa sa_handler
+to
+.Dv SIG_DFL .
+The defaults are process termination, possibly with core dump;

 no action; stopping the process; or continuing the process.
 See the signal list below for each signal's default action.
 If
 no action; stopping the process; or continuing the process.
 See the signal list below for each signal's default action.
 If

-.I sa_handler
-is SIG_IGN the signal is subsequently ignored,
-and pending instances of the signal are discarded.
-.PP
+.Fa sa_handler
+is
+.Dv SIG_IGN
+current and pending instances
+of the signal are ignored and discarded.
+.Pp

 Options may be specified by setting
 Options may be specified by setting

-.IR sa_flags .
-If the SA_NOCLDSTOP bit is set when installing a catching function
-for the SIGCHLD signal,
-the SIGCHLD signal will be generated only when a child process exits,
+.Em sa_flags .
+If the
+.Dv SA_NOCLDSTOP
+bit is set when installing a catching function
+for the
+.Dv SIGCHLD
+signal,
+the
+.Dv SIGCHLD
+signal will be generated only when a child process exits,

 not when a child process stops.
 not when a child process stops.

-Further, if the SA_ONSTACK bit is set in
-.I sa_flags,
+Further, if the
+.Dv SA_ONSTACK
+bit is set in
+.Em sa_flags ,

 the system will deliver the signal to the process on a
 the system will deliver the signal to the process on a

-.IR "signal stack" ,
+.Em "signal stack" ,

 specified with
 specified with

-.IR sigstack (2).
-.PP
-If a caught signal occurs during certain system calls,
-the call may be forced to terminate prematurely
-with an EINTR error return,
+.Xr sigstack 2 .
+.Pp
+If a signal is caught during the system calls listed below,
+the call may be forced to terminate
+with the error
+.Dv EINTR ,

 or the call may be restarted.
 Restart of pending calls is requested
 or the call may be restarted.
 Restart of pending calls is requested

-by setting the SA_RESTART bit in
-.I sa_flags.
+by setting the
+.Dv SA_RESTART
+bit in
+.Ar sa_flags .

 The affected system calls include
 The affected system calls include

-.IR read (2),
-.IR write (2),
-.IR sendto (2),
-.IR recvfrom (2),
-.IR sendmsg (2)
+.Xr read 2 ,
+.Xr write 2 ,
+.Xr sendto 2 ,
+.Xr recvfrom 2 ,
+.Xr sendmsg 2

 and
 and

-.IR recvmsg (2)
+.Xr recvmsg 2

 on a communications channel or a slow device (such as a terminal,
 but not a regular file)
 and during a
 on a communications channel or a slow device (such as a terminal,
 but not a regular file)
 and during a

-.IR wait (2)
+.Xr wait 2

 or
 or

-.IR ioctl (2).
+.Xr ioctl 2 .

 However, calls that have already committed are not restarted,
 but instead return a partial success (for example, a short read count).
 However, calls that have already committed are not restarted,
 but instead return a partial success (for example, a short read count).

-.PP
+.Pp

 After a
 After a

-.IR fork (2)
+.Xr fork 2

 or
 or

-.IR vfork (2)
-the child inherits
+.Xr vfork 2

 all signals, the signal mask, the signal stack,
 all signals, the signal mask, the signal stack,

-and the restart/interrupt flags.
-.PP
-.IR  Execve (2)
-resets all
-caught signals to default action and
+and the restart/interrupt flags are inherited by the child.
+.Pp
+.Xr Execve 2
+reinstates the default
+action for all signals which were caught and

 resets all signals to be caught on the user stack.
 Ignored signals remain ignored;
 the signal mask remains the same;
 signals that restart pending system calls continue to do so.
 resets all signals to be caught on the user stack.
 Ignored signals remain ignored;
 the signal mask remains the same;
 signals that restart pending system calls continue to do so.

-.PP
+.Pp

 The following is a list of all signals
 with names as in the include file
 The following is a list of all signals
 with names as in the include file

-.RI < signal.h >:
-.LP
-.nf
-.RS
-.ta \w'SIGVTALRM\0\0\0'u +\w'15*\*p\0\0'u
-SIGHUP 1       hangup
-SIGINT 2       interrupt
-SIGQUIT        3*      quit
-SIGILL 4*      illegal instruction
-SIGTRAP        5*\*p   trace trap
-SIGABRT        6*      \fIabort\fP() call (formerly SIGIOT)
-SIGEMT 7*\*p   EMT instruction
-SIGFPE 8*      floating point exception
-SIGKILL        9       kill (cannot be caught, blocked, or ignored)
-SIGBUS 10*\*p  bus error
-SIGSEGV        11*     segmentation violation
-SIGSYS 12*\*p  bad argument to system call
-SIGPIPE        13      write on a pipe with no one to read it
-SIGALRM        14      alarm clock
-SIGTERM        15      software termination signal
-SIGURG 16\*b\*p        urgent condition present on socket
-SIGSTOP        17\*d   stop (cannot be caught, blocked, or ignored)
-SIGTSTP        18\*d   stop signal generated from keyboard
-SIGCONT        19\*b   continue after stop
-SIGCHLD        20\*b   child status has changed
-SIGTTIN        21\*d   background read attempted from control terminal
-SIGTTOU        22\*d   background write attempted to control terminal
-SIGIO  23\*b\*p        i/o is possible on a descriptor (see \fIfcntl\fP(2))
-SIGXCPU        24\*p   cpu time limit exceeded (see \fIsetrlimit\fP(2))
-SIGXFSZ        25\*p   file size limit exceeded (see \fIsetrlimit\fP(2))
-SIGVTALRM      26\*p   virtual time alarm (see \fIsetitimer\fP(2))
-SIGPROF        27\*p   profiling timer alarm (see \fIsetitimer\fP(2))
-SIGWINCH       28\*b\*p        window size change
-SIGINFO        29\*b\*p        status request from keyboard
-SIGUSR1        30      user-defined signal 1
-SIGUSR2        31      user-defined signal 2
-.RE
-.fi
-.PP
-The default signal action is termination
-if the signal is not caught or ignored,
-except for signals marked with \*b or \*d.
-The starred signals in the list above cause termination with a core image.
-Signals marked with \*b are discarded if the action
-is SIG_DFL; signals marked
-with \*d cause the process to stop.
-The signals marked with \*p are not defined by POSIX.
-.SH NOTES
+.Aq Pa signal.h :
+.Bl -column SIGVTALARMXX "create core imagexxx"
+.It Sy "  NAME  " "      Default Action  " "                 Description"
+.It Dv SIGHUP No "     terminate process" "    terminal line hangup"
+.It Dv SIGINT No "     terminate process" "    interrupt program"
+.It Dv SIGQUIT No "    create core image" "    quit program"
+.It Dv SIGILL No "     create core image" "    illegal instruction"
+.It Dv SIGTRAP No "    create core image" "    trace trap"
+.It Dv SIGABRT No "    create core image" Xr   abort 2
+call (formerly
+.Dv SIGIOT )
+.It Dv SIGEMT No "     create core image" "    emulate instruction executed"
+.It Dv SIGFPE No "     create core image" "    floating-point exception"
+.It Dv SIGKILL No "    terminate process" "    kill program"
+.It Dv SIGBUS No "     create core image" "    bus error"
+.It Dv SIGSEGV No "    create core image" "    segmentation violation"
+.It Dv SIGSYS No "     create core image" "    system call given invalid argument"
+.It Dv SIGPIPE No "    terminate process" "    write on a pipe with no reader"
+.It Dv SIGALRM No "    terminate process" "    real-time timer expired"
+.It Dv SIGTERM No "    terminate process" "    software termination signal"
+.It Dv SIGURG No "     discard signal" "       urgent condition present on socket"
+.It Dv SIGSTOP No "    stop process" " stop (cannot be caught or ignored)"
+.It Dv SIGTSTP No "    stop process" " stop signal generated from keyboard"
+.It Dv SIGCONT No "    discard signal" "       continue after stop"
+.It Dv SIGCHLD No "    discard signal" "       child status has changed"
+.It Dv SIGTTIN No "    stop process" " background read attempted from control terminal"
+.It Dv SIGTTOU No "    stop process" " background write attempted to control terminal"
+.It Dv SIGIO No "      discard signal" Tn "    I/O"
+is possible on a descriptor (see
+.Xr fcntl 2 )
+.It Dv SIGXCPU No "    terminate process" "    cpu time limit exceeded (see"
+.Xr setrlimit 2 )
+.It Dv SIGXFSZ No "    terminate process" "    file size limit exceeded (see"
+.Xr setrlimit 2 )
+.It Dv SIGVTALRM No "  terminate process" "    virtual time alarm (see"
+.Xr setitimer 2 )
+.It Dv SIGPROF No "    terminate process" "    profiling timer alarm (see"
+.Xr setitimer 2 )
+.It Dv SIGWINCH No "   discard signal" "       Window size change"
+.It Dv SIGINFO No "    discard signal" "       status request from keyboard"
+.It Dv SIGUSR1 No "    terminate process" "    User defined signal 1"
+.It Dv SIGUSR2 No "    terminate process" "    User defined signal 2"
+.El
+.Sh NOTE

 The mask specified in 
 The mask specified in 

-.I act
-is not allowed to block SIGKILL or SIGSTOP.
+.Fa act
+is not allowed to block
+.Dv SIGKILL
+or
+.Dv SIGSTOP

 This is done silently by the system.
 This is done silently by the system.

-.SH "RETURN VALUE
+.Sh RETURN VALUES

 A 0 value indicated that the call succeeded.  A \-1 return value
 indicates an error occurred and
 A 0 value indicated that the call succeeded.  A \-1 return value
 indicates an error occurred and

-.I errno
+.Va errno

 is set to indicated the reason.
 is set to indicated the reason.

-.SH ERRORS
-.I Sigaction
+.Sh ERROR
+.Fn Sigaction

 will fail and no new signal handler will be installed if one
 of the following occurs:
 will fail and no new signal handler will be installed if one
 of the following occurs:

-.TP 15
-[EFAULT]
+.Tw Er
+.Tl Bq Er EFAULT

 Either
 Either

-.I act
+.Fa act

 or 
 or 

-.I oact
+.Fa oact

 points to memory that is not a valid part of the process
 address space.
 points to memory that is not a valid part of the process
 address space.

-.TP 15
-[EINVAL]
-.I Sig
+.Tl Bq Er EINVAL
+.Fa Sig

 is not a valid signal number.
 is not a valid signal number.

-.TP 15
-[EINVAL]
-An attempt is made to ignore or supply a handler for SIGKILL
-or SIGSTOP.
-.SH STANDARDS
+.Tl Bq Er EINVAL
+An attempt is made to ignore or supply a handler for
+.Em SIGKIL
+or
+.Dv SIGSTOP
+.Tl
+.Sh STANDARD

 The
 The

-.I sigaction
-function is defined by POSIX.1.
-The SA_ONSTACK and SA_RESTART flags are Berkeley extensions,
-as are the signals marked with \*p.
-Most of those signals are available on most BSD-derived systems.
-.SH "SEE ALSO"
-kill(1), ptrace(2), kill(2),
-sigaction(2), sigprocmask(2), sigsetops(2), sigsuspend(2),
-sigblock(2), sigsetmask(2), sigpause(2),
-sigstack(2), sigvec(2), setjmp(3), siginterrupt(3), tty(4)
-.SH "NOTES  (VAX-11)"
-The handler routine can be declared:
-.PP
-    void handler(sig, code, scp)
-    int sig, code;
-    struct sigcontext *scp;
-.PP
+.Nm sigaction
+function is defined by
+.St -p1003.1-88 .
+The
+.Dv SA_ONSTACK
+and
+.Dv SA_RESTART
+flags are Berkeley extensions,
+as are the signals,
+.Dv SIGTRAP ,
+.Dv SIGEMT ,
+.Dv SIGBUS ,
+.Dv SIGSYS ,
+.Dv SIGURG ,
+.Dv SIGIO ,
+.Dv SIGXCPU ,
+.Dv SIGXFSZ ,
+.Dv SIGVTALRM ,
+.Dv SIGPROF ,
+.Dv SIGWINCH ,
+and
+.Dv SIGINFO .
+Most of those signals are available on most
+.Tn BSD Ns \-derived
+systems.
+.Sh SEE ALSO
+.Xr kill 1 ,
+.Xr ptrace 2 ,
+.Xr kill 2 ,
+.Xr sigaction 2 ,
+.Xr sigprocmask 2 ,
+.Em sigsetops 2 ,
+.Xr sigsuspend 2 ,
+.Xr sigblock 2 ,
+.Xr sigsetmask 2 ,
+.Xr sigpause 2 ,
+.Xr sigstack 2 ,
+.Xr sigvec 2 ,
+.Xr setjmp 3 ,
+.Em siginterrupt 3 ,
+.Xr tty 4
+.Sh EXAMPLE
+On a
+.Tn VAX\-11,
+the handler routine can be declared:
+.Bd -literal -offset indent
+void handler(sig, code, scp)
+int sig, code;
+struct sigcontext *scp;
+.Ed
+.Pp

 Here
 Here

-.I sig
+.Fa sig

 is the signal number, into which the hardware faults and traps are
 mapped as defined below. 
 is the signal number, into which the hardware faults and traps are
 mapped as defined below. 

-.I Code
+.Em Code

 is a parameter that is either a constant
 is a parameter that is either a constant

-as given below or, for compatibility mode faults, the code provided by
+as given below or the code provided by

 the hardware (Compatibility mode faults are distinguished from the
 the hardware (Compatibility mode faults are distinguished from the

-other SIGILL traps by having PSL_CM set in the psl).
-.I Scp
+other
+.Dv SIGILL
+traps by having
+.Dv PSL_CM
+set in the psl).
+.Fa Scp

 is a pointer to the
 is a pointer to the

-.I sigcontext
+.Fa sigcontext

 structure (defined in
 structure (defined in

-.RI < signal.h >),
+.Aq Pa signal.h ) ,

 used to restore the context from before the signal.
 used to restore the context from before the signal.

-.PP
-The following defines the mapping of hardware traps to signals
-and codes.  All of these symbols are defined in
-.RI < signal.h >:
-.LP
-.ta \w'     Floating/decimal divide by zero   'u +\w'15*  'u +8n
-.nf
-   Hardware condition  Signal  Code
-
-Arithmetic traps:
-   Integer overflow    SIGFPE  FPE_INTOVF_TRAP
-   Integer division by zero    SIGFPE  FPE_INTDIV_TRAP
-   Floating overflow trap      SIGFPE  FPE_FLTOVF_TRAP
-   Floating/decimal division by zero   SIGFPE  FPE_FLTDIV_TRAP
-   Floating underflow trap     SIGFPE  FPE_FLTUND_TRAP
-   Decimal overflow trap       SIGFPE  FPE_DECOVF_TRAP
-   Subscript-range     SIGFPE  FPE_SUBRNG_TRAP
-   Floating overflow fault     SIGFPE  FPE_FLTOVF_FAULT
-   Floating divide by zero fault       SIGFPE  FPE_FLTDIV_FAULT
-   Floating underflow fault    SIGFPE  FPE_FLTUND_FAULT
-Length access control  SIGSEGV
-Protection violation   SIGBUS
-Reserved instruction   SIGILL  ILL_RESAD_FAULT
-Customer-reserved instr.       SIGEMT
-Reserved operand       SIGILL  ILL_PRIVIN_FAULT
-Reserved addressing    SIGILL  ILL_RESOP_FAULT
-Trace pending  SIGTRAP
-Bpt instruction        SIGTRAP
-Compatibility-mode     SIGILL  hardware supplied code
-Chme   SIGSEGV
-Chms   SIGSEGV
-Chmu   SIGSEGV
-.fi
-.SH BUGS
-This manual page is still confusing.