1.\" $NetBSD: syscall.2,v 1.16 2004/05/13 10:20:58 wiz Exp $ 2.\" 3.\" Copyright (c) 1980, 1991, 1993 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. Neither the name of the University nor the names of its contributors 15.\" may be used to endorse or promote products derived from this software 16.\" without specific prior written permission. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 19.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 22.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28.\" SUCH DAMAGE. 29.\" 30.\" @(#)syscall.2 8.1 (Berkeley) 6/16/93 31.\" 32.Dd June 16, 1993 33.Dt SYSCALL 2 34.Os 35.Sh NAME 36.Nm syscall , 37.Nm __syscall 38.Nd indirect system call 39.Sh LIBRARY 40.Lb libc 41.Sh SYNOPSIS 42.In sys/syscall.h 43.In unistd.h 44.Ft int 45.Fn syscall "int number" "..." 46.Ft quad_t 47.Fn __syscall "quad_t number" "..." 48.Sh DESCRIPTION 49.Fn syscall 50performs the system call whose assembly language 51interface has the specified 52.Fa number 53with the specified arguments. 54Symbolic constants for system calls can be found in the header file 55.Ao Pa sys/syscall.h Ac . 56The 57.Nm __syscall 58form should be used when one or more of the parameters is a 5964-bit argument to ensure that argument alignment is correct. 60This system call is useful for testing new system calls that 61do not have entries in the C library. 62.Sh RETURN VALUES 63The return values are defined by the system call being invoked. 64In general, a 0 return value indicates success. 65A \-1 return value indicates an error, 66and an error code is stored in 67.Va errno . 68.Sh HISTORY 69The 70.Fn syscall 71function call appeared in 72.Bx 4.0 . 73.Sh BUGS 74There is no way to simulate system calls that have multiple return values 75such as 76.Xr pipe 2 . 77.Pp 78Due to ABI implementation differences in passing struct or union 79type arguments to system calls between different processors, all 80system calls pass instead pointers to such structs or unions, even 81when the documentation of the system call mentions otherwise. 82The conversion between passing structs and unions is handled normally 83via userland stubs. 84The correct arguments for the kernel entry 85points for each system call can be found in the header file 86.Ao Pa sys/syscallargs.h Ac 87