91 lines
3.3 KiB
Groff
91 lines
3.3 KiB
Groff
.\" $NetBSD: ik.4,v 1.6 1999/12/15 23:44:55 abs Exp $
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.\"
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.\" Copyright (c) 1983, 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" from: @(#)ik.4 8.1 (Berkeley) 6/5/93
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.\"
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.Dd June 5, 1993
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.Dt IK 4 vax
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.Os
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.Sh NAME
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.Nm ik
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.Nd Ikonas frame buffer, graphics device interface
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.Sh SYNOPSIS
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.Cd "ik0 at uba? csr 0172460 vector ikintr"
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.Sh DESCRIPTION
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The
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.Nm ik
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driver
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provides an interface to an Ikonas frame buffer graphics device.
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Each minor device is a different frame buffer interface board.
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When the device is opened, its interface registers are mapped,
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via virtual memory, into the user processes address space.
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This allows the user process very high bandwidth to the frame buffer
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with no system call overhead.
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.Pp
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Bytes written or read from the device are
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.Tn DMA Ns 'ed
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from or to the interface.
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The frame buffer
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.Tn XY
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address, its addressing mode, etc. must be set up by the
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user process before calling write or read.
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.Pp
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Other communication with the driver is via ioctls.
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The
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.Dv IK_GETADDR
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.Xr ioctl 2
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returns the virtual address where the user process can
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find the interface registers.
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The
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.Dv IK_WAITINT
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.Xr ioctl
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suspends the user process until the ikonas device
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has interrupted (for whatever reason \(em the user process has to set
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the interrupt enables).
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.Sh FILES
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.Bl -tag -width /dev/ikxx -compact
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.It Pa /dev/ik
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.El
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.Sh DIAGNOSTICS
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None.
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.Sh HISTORY
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The
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.Nm
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driver appeared in
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.Bx 4.2 .
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.Sh BUGS
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An invalid access (e.g., longword) to a mapped interface register
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can cause the system to crash with a machine check.
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A user process could possibly cause infinite interrupts hence
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bringing things to a crawl.
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