1.\" 2.\" Copyright (c) 2005 The DragonFly Project. All rights reserved. 3.\" 4.\" This code is derived from software contributed to The DragonFly Project 5.\" by Hiten Pandya <hmp@backplane.com>. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 11.\" 1. Redistributions of source code must retain the above copyright 12.\" notice, this list of conditions and the following disclaimer. 13.\" 2. Redistributions in binary form must reproduce the above copyright 14.\" notice, this list of conditions and the following disclaimer in 15.\" the documentation and/or other materials provided with the 16.\" distribution. 17.\" 3. Neither the name of The DragonFly Project nor the names of its 18.\" contributors may be used to endorse or promote products derived 19.\" from this software without specific, prior written permission. 20.\" 21.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 22.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 23.\" LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 24.\" FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 25.\" COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 26.\" INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING, 27.\" BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 28.\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 29.\" AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 30.\" OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 31.\" OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32.\" SUCH DAMAGE. 33.\" 34.\" $NetBSD: physio.9,v 1.2 1996/11/11 00:05:12 lukem Exp $ 35.\" 36.\" Copyright (c) 1996 The NetBSD Foundation, Inc. 37.\" All rights reserved. 38.\" 39.\" This code is derived from software contributed to The NetBSD Foundation 40.\" by Paul Kranenburg. 41.\" 42.\" Redistribution and use in source and binary forms, with or without 43.\" modification, are permitted provided that the following conditions 44.\" are met: 45.\" 1. Redistributions of source code must retain the above copyright 46.\" notice, this list of conditions and the following disclaimer. 47.\" 2. Redistributions in binary form must reproduce the above copyright 48.\" notice, this list of conditions and the following disclaimer in the 49.\" documentation and/or other materials provided with the distribution. 50.\" 3. All advertising materials mentioning features or use of this software 51.\" must display the following acknowledgement: 52.\" This product includes software developed by the NetBSD 53.\" Foundation, Inc. and its contributors. 54.\" 4. Neither the name of The NetBSD Foundation nor the names of its 55.\" contributors may be used to endorse or promote products derived 56.\" from this software without specific prior written permission. 57.\" 58.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 59.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 60.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 61.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE 62.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 63.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 64.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 65.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 66.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 67.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 68.\" POSSIBILITY OF SUCH DAMAGE. 69.\" 70.\" $FreeBSD: src/share/man/man9/physio.9,v 1.6.2.4 2001/12/17 11:30:18 ru Exp $ 71.\" $DragonFly: src/share/man/man9/physio.9,v 1.4 2007/06/30 19:03:52 swildner Exp $ 72.\" 73.Dd July 31, 2005 74.Dt PHYSIO 9 75.Os 76.Sh NAME 77.Nm physio 78.Nd initiate I/O on raw devices 79.Sh SYNOPSIS 80.In sys/param.h 81.In sys/systm.h 82.In sys/buf.h 83.Ft int 84.Fn physio "dev_t dev" "struct uio *uio" "int ioflag" 85.Sh DESCRIPTION 86The 87.Fn physio 88is a helper function typically called from character device read and write 89routines to start I/O on a user process buffer. 90It will call the 91.Xr BUF_STRATEGY 9 92routine one or more times depending on the size of transfer which is 93described by the 94.Fa uio 95argument. 96.Pp 97The maximum amount of data transferable in one iteration of the 98.Nm 99function is determined by the maximum I/O size supported by the device 100.Fa dev , 101otherwise the value of 102.Dv DFLTPHYS 103is used. 104Until the I/O operation is complete, the calling process or thread is 105put to sleep with the wait message set to 106.Ql "physstr" . 107.Pp 108The 109.Nm 110function always awaits the completion of the entire requested transfer 111before returning, unless an error condition is detected earlier. 112.Pp 113A break-down of the arguments follow: 114.Bl -tag -width indent 115.It Fa dev 116The device to interact with by using it as with the 117.Xr BUF_STRATEGY 9 118routine in order to initiate I/O. 119.It Fa uio 120The description of the entire transfer as requested by the user process. 121.It Fa ioflag 122Direction of transfer; the only valid settings are 123.Dv B_READ 124or 125.Dv B_WRITE . 126.El 127.Sh RETURN VALUES 128If successful 129.Nm 130will return 0. 131.Pp 132The 133.Va errno 134value 135.Er EFAULT 136will be returned if the address range described by 137.Fa uio 138is not accessible by the calling process or thread. 139.Pp 140Note that the actual transfer size may be less than requested by 141.Fa uio 142if the device signals an 143.Dq end of file 144condition. 145.Sh SEE ALSO 146.Xr read 2 , 147.Xr write 2 148