.\" .\" Copyright (c) 2005 The DragonFly Project. All rights reserved. .\" .\" This code is derived from software contributed to The DragonFly Project .\" by Hiten Pandya . .\" .\" 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. Neither the name of The DragonFly Project nor the names of its .\" contributors may be used to endorse or promote products derived .\" from this software without specific, prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 .\" COPYRIGHT HOLDERS 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. .\" .\" $NetBSD: physio.9,v 1.2 1996/11/11 00:05:12 lukem Exp $ .\" .\" Copyright (c) 1996 The NetBSD Foundation, Inc. .\" All rights reserved. .\" .\" This code is derived from software contributed to The NetBSD Foundation .\" by Paul Kranenburg. .\" .\" 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 NetBSD .\" Foundation, Inc. and its contributors. .\" 4. Neither the name of The NetBSD Foundation nor the names of its .\" contributors may be used to endorse or promote products derived .\" from this software without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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. .\" .\" $FreeBSD: src/share/man/man9/physio.9,v 1.6.2.4 2001/12/17 11:30:18 ru Exp $ .\" $DragonFly: src/share/man/man9/physio.9,v 1.3 2005/07/31 01:51:43 hmp Exp $ .\" .Dd July 31, 2005 .Dt PHYSIO 9 .Os .Sh NAME .Nm physio .Nd initiate I/O on raw devices .Sh SYNOPSIS .In sys/param.h .In sys/systm.h .In sys/buf.h .Ft int .Fn physio "dev_t dev" "struct uio *uio" "int ioflag" .Sh DESCRIPTION The .Fn physio is a helper function typically called from character device read and write routines to start I/O on a user process buffer. It will call the .Xr BUF_STRATEGY 9 routine one or more times depending on the size of transfer which is described by the .Fa uio argument. .Pp The maximum amount of data transferable in one iteration of the .Nm function is determined by the maximum I/O size supported by the device .Fa dev , otherwise the value of .Dv DFLTPHYS is used. Until the I/O operation is complete, the calling process or thread is put to sleep with the wait message set to .Ql "physstr" . .Pp The .Nm function always awaits the completion of the entire requested transfer before returning, unless an error condition is detected earlier. .Pp A break-down of the arguments follow: .Bl -tag -width indent .It Fa dev The device to interact with by using it as with the .Xr BUF_STRATEGY 9 routine in order to initiate I/O. .It Fa uio The description of the entire transfer as requested by the user process. .It Fa ioflag Direction of transfer; the only valid settings are .Dv B_READ or .Dv B_WRITE . .El .Sh RETURN VALUES If successful .Nm will return 0. .Pp The errno value .Er EFAULT will be returned if the address range described by .Fa uio is not accessible by the calling process or thread. .Pp Note that the actual transfer size may be less than requested by .Fa uio if the device signals an .Dq end of file condition. .Sh SEE ALSO .Xr read 2 , .Xr write 2