'\" te
.\" Copyright (c) 1997, Sun Microsystems, Inc., All Rights Reserved
.TH physio 9F "2 Apr 1993" "SunOS 5.11" "Kernel Functions for Drivers"
.SH NAME
physio, minphys \- perform physical I/O
.SH SYNOPSIS
.LP
.nf
#include <sys/types.h>
#include <sys/buf.h>
#include <sys/uio.h>

\fBint\fR \fBphysio\fR(\fBint\fR(\fI*strat\fR)(\fIstruct buf *\fR), \fBstruct buf\fR \fI*bp\fR, \fBdev_t\fR \fIdev\fR, 
     \fBint\fR \fIrw\fR, \fBvoid\fR (\fI*mincnt\fR)(\fIstruct buf *\fR), \fBstruct uio\fR \fI*uio\fR);
.fi

.LP
.nf
\fBvoid\fR \fBminphys\fR(\fBstruct buf\fR \fI*bp\fR);
.fi

.SH INTERFACE LEVEL
.sp
.LP
Solaris DDI specific (Solaris DDI).
.SH PARAMETERS
.SS "\fBphysio()\fR"
.sp
.ne 2
.mk
.na
\fB\fIstrat\fR \fR
.ad
.RS 11n
.rt  
Pointer to device strategy routine.
.RE

.sp
.ne 2
.mk
.na
\fB\fIbp\fR \fR
.ad
.RS 11n
.rt  
Pointer to a \fBbuf\fR(9S) structure describing the transfer. If \fIbp\fR is set to \fINULL\fR then \fBphysio()\fR allocates one which is automatically released upon completion.
.RE

.sp
.ne 2
.mk
.na
\fB\fIdev\fR \fR
.ad
.RS 11n
.rt  
The device number.
.RE

.sp
.ne 2
.mk
.na
\fB\fIrw\fR \fR
.ad
.RS 11n
.rt  
Read/write flag. This is either \fBB_READ\fR when reading from the device, or \fBB_WRITE\fR when writing to the device.
.RE

.sp
.ne 2
.mk
.na
\fB\fImincnt\fR \fR
.ad
.RS 11n
.rt  
Routine which bounds the maximum transfer unit size.
.RE

.sp
.ne 2
.mk
.na
\fB\fIuio\fR \fR
.ad
.RS 11n
.rt  
Pointer to the \fBuio\fR structure which describes the user \fBI/O\fR request.
.RE

.SS "\fBminphys()\fR"
.sp
.ne 2
.mk
.na
\fB\fIbp\fR \fR
.ad
.RS 7n
.rt  
Pointer to a \fBbuf\fR structure.
.RE

.SH DESCRIPTION
.sp
.LP
\fBphysio()\fR performs unbuffered \fBI/O\fR operations between the device \fIdev\fR and the address space described in the \fBuio\fR structure.
.sp
.LP
Prior to the start of the transfer \fBphysio()\fR verifies the requested operation is valid by checking the protection of the address space specified in the \fBuio\fR structure. It then locks the pages involved in the \fBI/O\fR transfer so they can not be paged out. The device strategy routine, \fBstrat()\fR, is then called one or more times to perform the physical \fBI/O\fR operations. \fBphysio()\fR uses \fBbiowait\fR(9F) to block until \fBstrat()\fR has completed each transfer. Upon completion, or detection of an error, \fBphysio()\fR unlocks the pages and returns the error status.
.sp
.LP
\fBphysio()\fR uses \fBmincnt()\fR to bound the maximum transfer unit size to the system, or device, maximum length. \fBminphys()\fR is the system \fBmincnt()\fR routine for use with \fBphysio()\fR operations. Drivers which do not provide their own local \fBmincnt()\fR routines should call \fBphysio()\fR with \fBminphys()\fR.
.sp
.LP
\fBminphys()\fR limits the value of \fIbp\fR\fB->b_bcount\fR to a sensible default for the capabilities of the system. Drivers that provide their own \fBmincnt()\fR routine should also call \fBminphys()\fR to make sure they do not exceed the system limit.
.SH RETURN VALUES
.sp
.LP
\fBphysio()\fR returns:
.sp
.ne 2
.mk
.na
\fB\fB0\fR \fR
.ad
.RS 12n
.rt  
Upon success.
.RE

.sp
.ne 2
.mk
.na
\fB\fBnon-zero\fR\fR
.ad
.RS 12n
.rt  
Upon failure.
.RE

.SH CONTEXT
.sp
.LP
\fBphysio()\fR can be called from user context only.
.SH SEE ALSO
.sp
.LP
\fBstrategy\fR(9E), \fBbiodone\fR(9F), \fBbiowait\fR(9F), \fBbuf\fR(9S), \fBuio\fR(9S) 
.sp
.LP
\fIWriting Device Drivers for Oracle Solaris 11.2\fR 
.SH WARNINGS
.sp
.LP
Since \fBphysio()\fR calls \fBbiowait()\fR to block until each buf transfer is complete, it is the drivers responsibility to call \fBbiodone\fR(9F) when the transfer is complete, or \fBphysio()\fR will block forever.