'\" te
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.TH GETRBUF 9F "Jan 27, 2015"
.SH NAME
getrbuf \- get a raw buffer header
.SH SYNOPSIS
.LP
.nf
#include <sys/buf.h>
#include <sys/kmem.h>
#include <sys/ddi.h>



\fBstruct buf *\fR\fBgetrbuf\fR(\fBint\fR \fIsleepflag\fR);
.fi

.SH INTERFACE LEVEL
.LP
Architecture independent level 1 (DDI/DKI).
.SH PARAMETERS
.ne 2
.na
\fB\fIsleepflag\fR\fR
.ad
.RS 13n
Indicates whether driver should sleep for free space.
.RE

.SH DESCRIPTION
.LP
The \fBgetrbuf()\fR function allocates the space for a buffer header to the
caller. It is used in cases where a block driver is performing raw (character
interface) I/O and needs to set up a buffer header that is not associated with
the buffer cache.
.sp
.LP
The \fBgetrbuf()\fR function calls \fBkmem_alloc\fR(9F) to perform the memory
allocation. \fBkmem_alloc()\fR requires the information included in the
\fIsleepflag\fR argument. If \fIsleepflag\fR is set to \fBKM_SLEEP\fR, the
driver may sleep until the space is freed up. If \fIsleepflag\fR is set to
\fBKM_NOSLEEP\fR, the driver will not sleep.  In either case, a pointer to the
allocated space is returned or \fBNULL\fR to indicate that no space was
available.
.SH RETURN VALUES
.LP
The \fBgetrbuf()\fR function returns a pointer to the allocated buffer header,
or \fBNULL\fR if no space is available.
.SH CONTEXT
.LP
The \fBgetrbuf()\fR function can be called from user, interrupt, or kernel
context. (Drivers must not allow \fBgetrbuf()\fR to sleep if called from an
interrupt routine.)
.SH SEE ALSO
.LP
\fBbioinit\fR(9F), \fBfreerbuf\fR(9F), \fBkmem_alloc\fR(9F),
\fBkmem_free\fR(9F)
.sp
.LP
\fIWriting Device Drivers\fR