.\"	$OpenBSD: bio_register.9,v 1.6 2015/09/14 12:05:33 schwarze Exp $
.\"
.\" Copyright (c) 2006 David Gwynne <dlg@openbsd.org>
.\"
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.\" purpose with or without fee is hereby granted, provided that the above
.\" copyright notice and this permission notice appear in all copies.
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.Dd $Mdocdate: September 14 2015 $
.Dt BIO_REGISTER 9
.Os
.Sh NAME
.Nm bio_register ,
.Nm bio_unregister
.Nd block I/O ioctl tunnelling interface
.Sh SYNOPSIS
.In dev/biovar.h
.Ft int
.Fn bio_register "struct device *dev" "int (*bioctl)(struct device *, u_long, caddr_t)"
.Ft void
.Fn bio_unregister "struct device *dev"
.Sh DESCRIPTION
The block I/O ioctl tunnelling interface is used by drivers to register and
unregister ioctl handlers to be accessed via the
.Xr bio 4
device.
.Pp
.Fn bio_register
is called by the driver represented by
.Fa dev
to register the
.Fa bioctl
argument as the ioctl handler for itself.
.Pp
.Fn bio_unregister
is called to remove the ioctl handler previously registered with
.Fn bio_register
for the device represented by
.Fa dev .
.Pp
.Fn bio_register
and
.Fn bio_unregister
can be called during
.Xr autoconf 9
or from process context.
The
.Fa bioctl
callback is called from process context.
.Sh SEE ALSO
.Xr bio 4 ,
.Xr autoconf 9
.Sh HISTORY
The block I/O ioctl tunnelling interface first appeared in
.Ox 3.2 .
.Sh AUTHORS
The block I/O ioctl tunnelling interface was written by
.An Niklas Hallqvist Aq Mt niklas@openbsd.org .