1997-02-09 20:29:15 +00:00
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.\" Copyright (c) 1997
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.\" John-Mark Gurney. 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. Neither the name of the author nor the names of any co-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 John-Mark Gurney 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 AUTHOR 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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1999-08-28 00:22:10 +00:00
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.\" $FreeBSD$
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1997-02-09 20:29:15 +00:00
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.\"
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Move dynamic sysctl(8) variable creation for the cd(4) and da(4) drivers
out of cdregister() and daregister(), which are run from interrupt context.
The sysctl code does blocking mallocs (M_WAITOK), which causes problems
if malloc(9) actually needs to sleep.
The eventual fix for this issue will involve moving the CAM probe process
inside a kernel thread. For now, though, I have fixed the issue by moving
dynamic sysctl variable creation for these two drivers to a task queue
running in a kernel thread.
The existing task queues (taskqueue_swi and taskqueue_swi_giant) run in
software interrupt handlers, which wouldn't fix the problem at hand. So I
have created a new task queue, taskqueue_thread, that runs inside a kernel
thread. (It also runs outside of Giant -- clients must explicitly acquire
and release Giant in their taskqueue functions.)
scsi_cd.c: Remove sysctl variable creation code from cdregister(), and
move it to a new function, cdsysctlinit(). Queue
cdsysctlinit() to the taskqueue_thread taskqueue once we
have fully registered the cd(4) driver instance.
scsi_da.c: Remove sysctl variable creation code from daregister(), and
move it to move it to a new function, dasysctlinit().
Queue dasysctlinit() to the taskqueue_thread taskqueue once
we have fully registered the da(4) instance.
taskqueue.h: Declare the new taskqueue_thread taskqueue, update some
comments.
subr_taskqueue.c:
Create the new kernel thread taskqueue. This taskqueue
runs outside of Giant, so any functions queued to it would
need to explicitly acquire/release Giant if they need it.
cd.4: Update the cd(4) man page to talk about the minimum command
size sysctl/loader tunable. Also note that the changer
variables are available as loader tunables as well.
da.4: Update the da(4) man page to cover the retry_count,
default_timeout and minimum_cmd_size sysctl variables/loader
tunables. Remove references to /dev/r???, they aren't used
any longer.
cd.9: Update the cd(9) man page to describe the CD_Q_10_BYTE_ONLY
quirk.
taskqueue.9: Update the taskqueue(9) man page to describe the new thread
task queue, and the taskqueue_swi_giant queue.
MFC after: 3 days
2003-09-03 04:46:28 +00:00
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.Dd September 2, 2003
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1997-02-23 18:00:03 +00:00
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.Dt CD 9
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2001-07-10 15:31:11 +00:00
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.Os
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1997-02-09 20:29:15 +00:00
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.Sh NAME
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.Nm cd
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1998-10-12 04:09:49 +00:00
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.Nd CDROM driver for the CAM SCSI subsystem
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1997-02-09 20:29:15 +00:00
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.Sh DESCRIPTION
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1997-02-09 21:08:52 +00:00
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The
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.Nm
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2001-08-10 17:35:21 +00:00
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device driver provides a read only interface for CDROM drives
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.Tn ( SCSI
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1998-10-12 04:09:49 +00:00
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type 5)
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2001-08-10 17:35:21 +00:00
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and WORM drives
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.Tn ( SCSI
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1998-10-12 04:09:49 +00:00
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type 4)
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that support CDROM type commands.
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Some drives don't behave as the driver expects. See the section
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1997-02-09 20:29:15 +00:00
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QUIRKS for info on possible flags.
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.Sh QUIRKS
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Each
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.Tn CD-ROM
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device can have different interpretations of the
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.Tn SCSI
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spec. This can lead to drives requiring special handling in the driver. The
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2002-04-15 06:02:58 +00:00
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following is a list of quirks that the driver recognize.
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1997-02-09 20:29:15 +00:00
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.Bl -tag -width CD_Q_BCD_TRACKS
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.It Dv CD_Q_NO_TOUCH
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This flag tell the driver not to probe the drive at attach time to see if
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1998-10-12 04:09:49 +00:00
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there is a disk in the drive and find out what size it is. This flag is
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currently unimplemented in the CAM
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2000-11-20 18:41:33 +00:00
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.Nm
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1998-10-12 04:09:49 +00:00
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driver.
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1997-02-09 20:29:15 +00:00
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.It Dv CD_Q_BCD_TRACKS
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This flag is for broken drives that return the track numbers in packed BCD
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1997-04-02 09:41:16 +00:00
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instead of straight decimal. If the drive seems to skip tracks
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2001-08-07 15:48:51 +00:00
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(tracks 10-15 are skipped)
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1997-02-09 20:29:15 +00:00
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then you have a drive that is in need of this flag.
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1998-10-12 04:09:49 +00:00
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.It Dv CD_Q_NO_CHANGER
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This flag tells the driver that the device in question is not a changer.
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This is only necessary for a CDROM device with multiple luns that are not a
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part of a changer.
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.It Dv CD_Q_CHANGER
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This flag tells the driver that the given device is a multi-lun changer.
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In general, the driver will figure this out automatically when it sees a
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LUN greater than 0. Setting this flag only has the effect of telling the
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driver to run the initial read capacity command for LUN 0 of the changer
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through the changer scheduling code.
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Move dynamic sysctl(8) variable creation for the cd(4) and da(4) drivers
out of cdregister() and daregister(), which are run from interrupt context.
The sysctl code does blocking mallocs (M_WAITOK), which causes problems
if malloc(9) actually needs to sleep.
The eventual fix for this issue will involve moving the CAM probe process
inside a kernel thread. For now, though, I have fixed the issue by moving
dynamic sysctl variable creation for these two drivers to a task queue
running in a kernel thread.
The existing task queues (taskqueue_swi and taskqueue_swi_giant) run in
software interrupt handlers, which wouldn't fix the problem at hand. So I
have created a new task queue, taskqueue_thread, that runs inside a kernel
thread. (It also runs outside of Giant -- clients must explicitly acquire
and release Giant in their taskqueue functions.)
scsi_cd.c: Remove sysctl variable creation code from cdregister(), and
move it to a new function, cdsysctlinit(). Queue
cdsysctlinit() to the taskqueue_thread taskqueue once we
have fully registered the cd(4) driver instance.
scsi_da.c: Remove sysctl variable creation code from daregister(), and
move it to move it to a new function, dasysctlinit().
Queue dasysctlinit() to the taskqueue_thread taskqueue once
we have fully registered the da(4) instance.
taskqueue.h: Declare the new taskqueue_thread taskqueue, update some
comments.
subr_taskqueue.c:
Create the new kernel thread taskqueue. This taskqueue
runs outside of Giant, so any functions queued to it would
need to explicitly acquire/release Giant if they need it.
cd.4: Update the cd(4) man page to talk about the minimum command
size sysctl/loader tunable. Also note that the changer
variables are available as loader tunables as well.
da.4: Update the da(4) man page to cover the retry_count,
default_timeout and minimum_cmd_size sysctl variables/loader
tunables. Remove references to /dev/r???, they aren't used
any longer.
cd.9: Update the cd(9) man page to describe the CD_Q_10_BYTE_ONLY
quirk.
taskqueue.9: Update the taskqueue(9) man page to describe the new thread
task queue, and the taskqueue_swi_giant queue.
MFC after: 3 days
2003-09-03 04:46:28 +00:00
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.It Dv CD_Q_10_BYTE_ONLY
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This flag tells the driver that the given device only accepts 10 byte MODE
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SENSE/MODE SELECT commands. In general these types of quirks should not be
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added to the
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.Xr cd 4
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driver. The reason is that the driver does several things to attempt to
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determine whether the drive in question needs 10 byte commands. First, it
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issues a CAM Path Inquiry command to determine whether the protocol that
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the drive speaks typically only allows 10 byte commands. (ATAPI and USB
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are two prominent examples of protocols where you generally only want to
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send 10 byte commands.) Then, if it gets an ILLEGAL REQUEST error back
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from a 6 byte MODE SENSE or MODE SELECT command, it attempts to send the 10
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byte version of the command instead. The only reason you would need a
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quirk is if your drive uses a protocol (e.g.
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.Tn SCSI )
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that typically doesn't have a problem with 6 byte commands.
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1997-02-09 20:29:15 +00:00
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.El
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.Sh FILES
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1998-10-12 04:09:49 +00:00
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.Bl -tag -width /sys/cam/scsi/scsi_cd.c -compact
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.It Pa /sys/cam/scsi/scsi_cd.c
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is the driver source file.
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1997-02-09 20:29:15 +00:00
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.El
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.Sh SEE ALSO
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.Xr cd 4 ,
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1998-10-16 00:26:28 +00:00
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.Xr scsi 4
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1997-02-09 20:29:15 +00:00
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.Sh HISTORY
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The
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.Nm
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manual page first appeared in
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1997-02-17 15:22:20 +00:00
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.Fx 2.2 .
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1998-03-12 07:31:21 +00:00
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.Sh AUTHORS
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2000-11-22 09:35:58 +00:00
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.An -nosplit
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1997-02-09 20:29:15 +00:00
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This
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1998-03-12 07:31:21 +00:00
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manual page was written by
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.An John-Mark Gurney Aq gurney_j@efn.org .
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1998-10-12 04:09:49 +00:00
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It was updated for CAM and
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.Fx 3.0
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by
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1999-08-15 10:48:36 +00:00
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.An Kenneth Merry Aq ken@FreeBSD.org .
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