Current File : //usr/share/man/man9f/bp_mapin.9f

'\" te
.\" Copyright (c) 1992, 2010, Oracle and/or its affiliates. All rights reserved.
.\" Copyright 1989 AT&T
.TH bp_mapin 9F "21 Dec 2010" "SunOS 5.11" "Kernel Functions for Drivers"
.SH NAME
bp_mapin \- allocate virtual address space
.SH SYNOPSIS
.LP
.nf
#include <sys/types.h>
#include <sys/buf.h>

\fBvoid\fR \fBbp_mapin\fR(\fBstruct buf *\fR\fIbp\fR);
.fi

.SH INTERFACE LEVEL
.sp
.LP
Architecture independent level 1 (DDI/DKI).
.SH PARAMETERS
.sp
.ne 2
.mk
.na
\fB\fIbp\fR\fR
.ad
.RS 6n
.rt  
Pointer to the buffer header structure.
.RE

.SH DESCRIPTION
.sp
.LP
The \fBbp_mapin()\fR function makes buffer data accessible to a driver by mapping the data into a contiguous kernel virtual address region. After \fBbp_mapin()\fR, the mapped buffer is accessible via the \fIbp\fR\(em>\fIb_un.b_addr\fR field of the \fBbuf\fR(9S) structure.
.sp
.LP
If \fBbp_mapin()\fR is unable to establish a mapping, it returns without allocating space and no mapping is performed.
.sp
.LP
Any resources associated with establishing the mapping are deallocated by the \fBbp_mapout\fR(9F) function.
.SH CONTEXT
.sp
.LP
The \fBbp_mapin()\fR function can be called from user and kernel contexts.
.SH SEE ALSO
.sp
.LP
\fBbioaligned\fR(9F), \fBbp_mapout\fR(9F), \fBbuf\fR(9S) 
.sp
.LP
\fIWriting Device Drivers for Oracle Solaris 11.2\fR 
.SH WARNINGS
.sp
.LP
Because \fBbp_mapin()\fR does not keep a reference count, \fBbp_mapout()\fR will wipe out any kernel mapping, including mappings that a layer above the device driver might still rely on.  See \fBbp_mapout\fR(9F) for details.
.sp
.LP
When a driver needs to look directly at buffer data, it should call \fBbp_mapin()\fR without conditioning the call on other aspects of the \fBbuf\fR(9S) structure like \fIb_flags\fR.
.sp
.LP
To check alignment of buffer memory, it may be more efficient for a driver to use \fBbioaligned\fR(9F) instead of \fBbp_mapin()\fR.