7ddcd25763
Add information on target mode. Add more entries to the bugs sections (all having to do with target mode).
301 lines
10 KiB
Groff
301 lines
10 KiB
Groff
.\"
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.\" Copyright (c) 1995, 1996, 1997, 1998, 2000
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.\" Justin T. Gibbs. 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. The name of the author may not be used to endorse or promote products
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.\" derived from this software without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd February 13, 2000
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.Dt AHC 4
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.Os FreeBSD
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.Sh NAME
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.Nm ahc
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.Nd Adaptec VL/EISA/PCI SCSI host adapter driver
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.Sh SYNOPSIS
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For one or more VL/EISA cards:
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.Cd device eisa
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.Cd device ahc
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.Pp
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For one or more PCI cards:
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.Cd device pci
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.Cd device ahc
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.Pp
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To allow PCI adapters to use memory mapped I/O if enabled:
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.Cd options AHC_ALLOW_MEMIO
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.Pp
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To configure one or more controllers to assume the target role:
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.Cd options AHC_TMODE_ENABLE <bitmask of units>
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.Pp
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For one or more SCSI busses:
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.Cd device scbus0 at ahc0
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.Sh DESCRIPTION
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This driver provides access to the
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.Tn SCSI
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bus(es) connected to Adaptec
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.Tn AIC7770,
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.Tn AIC7850,
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.Tn AIC7860,
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.Tn AIC7870,
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.Tn AIC7880,
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.Tn AIC7890,
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.Tn AIC7891,
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.Tn AIC7892,
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.Tn AIC7895,
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.Tn AIC7896,
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.Tn AIC7897
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and
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.Tn AIC7899
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host adapter chips.
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These chips are found on many motherboards as well as the following
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Adaptec SCSI controller cards:
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.Tn 274X(W),
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.Tn 274X(T),
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.Tn 284X,
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.Tn 2910,
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.Tn 2915,
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.Tn 2920,
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.Tn 2930C,
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.Tn 2930U2,
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.Tn 2940,
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.Tn 2940U,
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.Tn 2940AU,
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.Tn 2940UW,
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.Tn 2940UW Dual,
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.Tn 2940UW Pro,
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.Tn 2940U2W,
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.Tn 2940U2B,
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.Tn 2950U2W,
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.Tn 2950U2B,
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.Tn 19160B,
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.Tn 29160B,
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.Tn 29160N,
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.Tn 3940,
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.Tn 3940U,
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.Tn 3940AU,
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.Tn 3940UW,
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.Tn 3940AUW,
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.Tn 3940U2W,
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.Tn 3950U2,
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.Tn 3960,
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.Tn 39160,
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.Tn 3985,
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and
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.Tn 4944UW.
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.Pp
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Driver features include support for twin and wide busses,
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fast, ultra or ultra2 synchronous transfers depending on controller type,
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tagged queuing, SCB paging, and target mode.
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.Pp
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Memory mapped I/O can be enabled for PCI devices with the
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.Dq Dv AHC_ALLOW_MEMIO
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configuration option.
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Memory mapped I/O is more efficient than the alternative, programmed I/O.
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Most PCI BIOSes will map devices so that either technique for communicating
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with the card is available.
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In some cases,
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usually when the PCI device is sitting behind a PCI->PCI bridge,
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the BIOS may fail to properly initialize the chip for memory mapped I/O.
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The typical symptom of this problem is a system hang if memory mapped I/O
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is attempted.
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Most modern motherboards perform the initialization correctly and work fine
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with this option enabled.
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.Pp
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Individual controllers may be configured to operate in the target role
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through the
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.Dq Dv AHC_TMODE_ENABLE
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configuration option. The value assigned to this option should be a bitmap
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of all units where target mode is desired.
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For example, a value of 0x25, would enable target mode on units 0, 2, and 5.
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.Pp
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Per target configuration performed in the
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.Tn SCSI-Select
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menu, accessible at boot
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in
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.No non- Ns Tn EISA
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models,
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or through an
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.Tn EISA
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configuration utility for
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.Tn EISA
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models,
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is honored by this driver.
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This includes synchronous/asynchronous transfers,
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maximum synchronous negotiation rate,
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wide transfers,
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disconnection,
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the host adapter's SCSI ID,
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and,
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in the case of
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.Tn EISA
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Twin Channel controllers,
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the primary channel selection.
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For systems that store non-volatile settings in a system specific manner
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rather than a serial eeprom directly connected to the aic7xxx controller,
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the
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.Tn BIOS
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must be enabled for the driver to access this information.
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This restriction applies to all
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.Tn EISA
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and many motherboard configurations.
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.Pp
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Note that I/O addresses are determined automatically by the probe routines,
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but care should be taken when using a 284x
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.Pq Tn VESA No local bus controller
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in an
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.Tn EISA
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system. The jumpers setting the I/O area for the 284x should match the
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.Tn EISA
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slot into which the card is inserted to prevent conflicts with other
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.Tn EISA
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cards.
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.Pp
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Performance and feature sets vary throughout the aic7xxx product line.
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The following table provides a comparison of the different chips supported
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by the
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.Nm
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driver. Note that wide and twin channel features, although always supported
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by a particular chip, may be disabled in a particular motherboard or card
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design.
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.Pp
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.Bd -filled -offset indent
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.Bl -column "aic7770 " "10 " "EISA/VL " "10MHz " "16bit " "SCBs " Features
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.Em "Chip MIPS Bus MaxSync MaxWidth SCBs Features"
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aic7770 10 EISA/VL 10MHz 16Bit 4 1
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aic7850 10 PCI/32 10MHz 8Bit 3
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aic7860 10 PCI/32 20MHz 8Bit 3
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aic7870 10 PCI/32 10MHz 16Bit 16
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aic7880 10 PCI/32 20MHz 16Bit 16
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aic7890 20 PCI/32 40MHz 16Bit 16 3 4 5 6 7 8
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aic7891 20 PCI/64 40MHz 16Bit 16 3 4 5 6 7 8
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aic7892 20 PCI/64 80MHz 16Bit 16 3 4 5 6 7 8
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aic7895 15 PCI/32 20MHz 16Bit 16 2 3 4 5
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aic7895C 15 PCI/32 20MHz 16Bit 16 2 3 4 5 8
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aic7896 20 PCI/32 40MHz 16Bit 16 2 3 4 5 6 7 8
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aic7897 20 PCI/64 40MHz 16Bit 16 2 3 4 5 6 7 8
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aic7899 20 PCI/64 80MHz 16Bit 16 2 3 4 5 6 7 8
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.El
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.Pp
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.Bl -enum -compact
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.It
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Multiplexed Twin Channel Device - One controller servicing two busses.
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.It
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Multi-function Twin Channel Device - Two controllers on one chip.
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.It
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Command Channel Secondary DMA Engine - Allows scatter gather list and
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SCB prefetch.
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.It
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64 Byte SCB Support - SCSI CDB is embedded in the SCB to eliminate an extra DMA.
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.It
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Block Move Instruction Support - Doubles the speed of certain sequencer
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operations.
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.It
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.Sq Bayonet
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style Scatter Gather Engine - Improves S/G prefetch performance.
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.It
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Queuing Registers - Allows queuing of new transactions without pausing the
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sequencer.
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.It
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Multiple Target IDs - Allows the controller to respond to selection as a
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target on multiple SCSI IDs.
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.El
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.Ed
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.Pp
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.Sh SCSI CONTROL BLOCKS (SCBs)
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Every transaction sent to a device on the SCSI bus is assigned a
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.Sq SCSI Control Block
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(SCB). The SCB contains all of the information required by the
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controller to process a transaction. The chip feature table lists
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the number of SCBs that can be stored in on-chip memory. All chips
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with model numbers greater than or equal to 7870 allow for the on chip
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SCB space to be augmented with external SRAM up to a maximum of 255 SCBs.
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Very few Adaptec controller configurations have external SRAM.
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.Pp
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If external SRAM is not available, SCBs are a limited resource.
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Using the SCBs in a straight forward manner would only allow the dirver to
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handle as many concurrent transactions as there are physical SCBs.
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To fully utilize the SCSI bus and the devices on it,
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requires much more concurrency.
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The solution to this problem is
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.Em SCB Paging ,
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a concept similar to memory paging. SCB paging takes advantage of
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the fact that devices usually disconnect from the SCSI bus for long
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periods of time without talking to the controller. The SCBs
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for disconnected transactions are only of use to the controller
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when the transfer is resumed. When the host queues another transaction
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for the controller to execute, the controller firmware will use a
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free SCB if one is available. Otherwise, the state of the most recently
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disconnected (and therefor most likely to stay disconnected) SCB is
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saved, via dma, to host memory, and the local SCB reused to start
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the new transaction. This allows the controller to queue up to
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255 transactions regardless of the amount of SCB space. Since the
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local SCB space serves as a cache for disconnected transactions, the
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more SCB space available, the less host bus traffic consumed saving
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and restoring SCB data.
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.Sh BUGS
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Some Quantum drives (at least the Empire 2100 and 1080s) will not run on an
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.Tn AIC7870
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Rev B in synchronous mode at 10MHz. Controllers with this problem have a
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42 MHz clock crystal on them and run slightly above 10MHz. This confuses
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the drive and hangs the bus. Setting a maximum synchronous negotiation rate
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of 8MHz in the
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.Tn SCSI-Select
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utility will allow normal operation.
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.Pp
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Double Transition clocking is not yet supported for Ultra160 controllers.
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This limits these controllers to 40MHz or 80MB/s.
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.Pp
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Although the Ultra2 and Ultra160 products have sufficient instruction
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ram space to support both the initiator and target roles concurrently,
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this configuration is disabled in favor of allowing the target role
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to respond on multiple target ids. A method for configuring dual
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role mode should be provided.
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.Pp
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Tagged Queuing is not supported in target mode.
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.Pp
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Reselection in target mode fails to function correctly on all high
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voltage differential boards as shipped by Adaptec. Information on
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how to modify HVD board to work correctly in target mode is available
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from Adaptec.
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.Sh SEE ALSO
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.Xr aha 4 ,
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.Xr ahb 4 ,
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.Xr cd 4 ,
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.Xr da 4 ,
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.Xr sa 4 ,
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.Xr scsi 4
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.Sh AUTHORS
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The
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.Nm
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driver, the
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.Tn AIC7xxx
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sequencer-code assembler,
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and the firmware running on the aic7xxx chips was written by
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.An Justin T. Gibbs .
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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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.Fx 2.0 .
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