Update to include all supported chips.
Add a table comparing the features of all aic7xxx chips. Clean up the discussion of SCB paging. Reviewed by: Kenneth Merry <ken@FreeBSD.org>
This commit is contained in:
Justin T. Gibbs
parent
28ed4514a2
commit
0effaa9f7e
@ -1,5 +1,5 @@
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.\"
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.\"
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.\" Copyright (c) 1995, 1996, 1997
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.\" Copyright (c) 1995, 1996, 1997, 1998
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.\" Justin T. Gibbs. All rights reserved.
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.\" Justin T. Gibbs. All rights reserved.
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.\"
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" Redistribution and use in source and binary forms, with or without
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||||||
@ -24,9 +24,9 @@
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.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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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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.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\"
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.\" $Id: ahc.4,v 1.11 1998/06/08 06:11:58 jkoshy Exp $
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.\" $Id: ahc.4,v 1.12 1998/06/13 19:06:49 steve Exp $
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.\"
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.\"
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.Dd April 20, 1996
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.Dd October 15, 1998
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.Dt AHC 4 i386
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.Dt AHC 4 i386
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.Os FreeBSD
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.Os FreeBSD
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.Sh NAME
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.Sh NAME
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@ -41,12 +41,6 @@ For one or more PCI cards:
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.Cd controller pci0
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.Cd controller pci0
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.Cd controller ahc0
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.Cd controller ahc0
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.Pp
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.Pp
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To enable SCB paging:
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.Cd options AHC_SCBPAGING_ENABLE
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.Pp
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To enable tagged queueing:
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.Cd options AHC_TAGENABLE
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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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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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.Cd options AHC_ALLOW_MEMIO
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.Pp
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.Pp
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@ -55,59 +49,49 @@ For one or more SCSI busses:
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.Sh DESCRIPTION
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.Sh DESCRIPTION
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This driver provides access to the
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This driver provides access to the
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.Tn SCSI
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.Tn SCSI
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bus(es) connected to Adaptec
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bus(es) connected to Adaptec
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274x, 284x, 2940, 3940, or controllers based on the
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.Tn AIC7770,
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.Tn AIC7770,
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.Tn AIC7850,
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.Tn AIC7850,
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.Tn AIC7860,
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.Tn AIC7860,
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.Tn AIC7870,
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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 AIC7895,
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.Tn AIC7896,
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or
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or
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.Tn AIC7880
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.Tn AIC7897
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host adapter chips.
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host adapter chips.
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Features include support for twin and wide busses,
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These chips are found on many motherboards as well as the following
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ultra
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Adaptec SCSI controller cards:
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.Tn SCSI,
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.Tn 274X(W),
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two active commands at a time per non-tagged queueing target,
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.Tn 274X(T),
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tagged queuing,
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.Tn 284X,
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.Tn 2920C,
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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 2940U2W,
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.Tn 2940U2B,
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.Tn 2950U2W,
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.Tn 2950U2B,
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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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and
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.Tn 3985.
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.Pp
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Driver features include support for twin and wide busses,
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fast, ultra and ultra2 synchronous transfers depending on controller type,
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tagged queueing,
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and SCB paging.
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and SCB paging.
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.Pp
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.Pp
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The number of concurrent transactions allowed is chip dependent
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Memory mapped I/O can be enabled for PCI devices with the
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and ranges from 3 to 16.
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On PCI adapters,
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this number can be increased with the SCB paging option.
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SCB paging implements an algorithm to 'page-out' transactions
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that are in the disconnected state so that the freed space in
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the controller's memory can be used to start additional transactions.
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On the aic7880 and aic7870,
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this increases the maximum number of outstanding transactions from 16 to 255.
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On the aic7850 and aic7860 controllers, this maximum rises from 3 to 8.
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During the hardware probe,
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a diagnostic showing the ratio of hardware supported 'slots' to number
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of transactions is printed.
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SCB paging is enabled with the
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.Dq Dv AHC_SCBPAGING_ENABLE
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configuration option.
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This option will likely be removed and become the default behavior for
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adapters that support it,
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in the near future.
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.Pp
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Tagged queueing is enabled with the
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.Dq Dv AHC_TAGENABLE
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configuration option.
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Tagged queueing allows multiple transactions to be queued at the device
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level instead of the host level,
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allowing the device to re-order I/O to minimize seeks,
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seek distance,
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and to increase throughput.
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Tagged queueing can have a significant impact on performance for seek
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bound applications and should be enabled for most configurations.
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Unfortunately, some devices that claim to support tagged queueing fail
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miserably when it is used.
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The only reason tagged queueing remains as a controller option is as a
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stop gap measure until a mechanism to detect these broken devices and to
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control this feature on a per device basis is in place.
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.Pp
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Memory mapped I/O can be enabled with the
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.Dq Dv AHC_ALLOW_MEMIO
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.Dq Dv AHC_ALLOW_MEMIO
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configuration option.
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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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Memory mapped I/O is more efficient than the alternative, programmed I/O.
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@ -139,7 +123,12 @@ must be enabled for
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adaptors. This includes synchronous/asynchronous transfers,
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adaptors. This includes synchronous/asynchronous transfers,
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maximum synchronous negotiation rate,
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maximum synchronous negotiation rate,
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disconnection,
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disconnection,
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and the host adapter's SCSI ID.
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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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.Pp
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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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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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but care should be taken when using a 284x
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@ -151,35 +140,110 @@ system. Ensure that the jumpers setting the I/O area for the 284x match the
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slot into which the card is inserted to prevent conflicts with other
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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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.Tn EISA
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cards.
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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
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aic7891 20 PCI/64 40MHz 16Bit 16 3 4 5 6 7
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aic7895 15 PCI/32 20MHz 16Bit 16 2 3 4 5
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aic7896 20 PCI/32 40MHz 16Bit 16 2 3 4 5 6 7
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aic7897 20 PCI/64 40MHz 16Bit 16 2 3 4 5 6 7
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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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Queueing Registers - Allows queueing of new transactions without pausing the
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sequencer.
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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 have external SRAM.
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If external SRAM is not available, SCBs are a limited resource and
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using them in a straight forward manner would only allow us to
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keep as many transactions as there are SCBs outstanding at a time.
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This would not allow enough concurrency to fully utilize the SCSI
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bus and it's devices. 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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.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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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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.Tn AIC7870
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Rev B in synchronous mode at 10MHz. Controllers with this problem have a
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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 causes the
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42 MHz clock crystal on them and run slightly above 10MHz. This confuses
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drive much confusion. Setting a maximum synchronous negotiation rate of 8MHz
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the drive and hangs the bus. Setting a maximum synchronous negotiation rate
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in the
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of 8MHz in the
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.Tn SCSI-Select
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.Tn SCSI-Select
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utility
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utility
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will allow normal function.
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will allow normal operation.
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.Sh SEE ALSO
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.Sh SEE ALSO
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.Xr aha 4 ,
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.Xr aha 4 ,
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.Xr ahb 4 ,
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.Xr ahb 4 ,
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.Xr cd 4 ,
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.Xr cd 4 ,
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.Xr scsi 4 ,
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.Xr scsi 4 ,
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.Xr sd 4 ,
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.Xr da 4 ,
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.Xr st 4
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.Xr sa 4
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.Sh AUTHORS
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.Sh AUTHORS
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The
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The
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.Nm
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.Nm
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driver was written by
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driver, the
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.An Justin Gibbs .
|
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The
|
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.Tn AIC7xxx
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.Tn AIC7xxx
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sequencer-code assembler was
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sequencer-code assember,
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written by
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and the firmware running on the aic7xxx chips was written by
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.An John Aycock .
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.An Justin T. Gibbs .
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.Sh HISTORY
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.Sh HISTORY
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The
|
The
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.Nm
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.Nm
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driver appeared in
|
driver appeared in
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.Fx 2.1 .
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.Fx 2.0 .
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@ -1,5 +1,5 @@
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.\"
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.\"
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||||||
.\" Copyright (c) 1995, 1996, 1997
|
.\" Copyright (c) 1995, 1996, 1997, 1998
|
||||||
.\" Justin T. Gibbs. All rights reserved.
|
.\" Justin T. Gibbs. All rights reserved.
|
||||||
.\"
|
.\"
|
||||||
.\" Redistribution and use in source and binary forms, with or without
|
.\" Redistribution and use in source and binary forms, with or without
|
||||||
@ -24,9 +24,9 @@
|
|||||||
.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
|
.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
|
||||||
.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
|
.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
|
||||||
.\"
|
.\"
|
||||||
.\" $Id: ahc.4,v 1.11 1998/06/08 06:11:58 jkoshy Exp $
|
.\" $Id: ahc.4,v 1.12 1998/06/13 19:06:49 steve Exp $
|
||||||
.\"
|
.\"
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||||||
.Dd April 20, 1996
|
.Dd October 15, 1998
|
||||||
.Dt AHC 4 i386
|
.Dt AHC 4 i386
|
||||||
.Os FreeBSD
|
.Os FreeBSD
|
||||||
.Sh NAME
|
.Sh NAME
|
||||||
@ -41,12 +41,6 @@ For one or more PCI cards:
|
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.Cd controller pci0
|
.Cd controller pci0
|
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.Cd controller ahc0
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.Cd controller ahc0
|
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.Pp
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.Pp
|
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To enable SCB paging:
|
|
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.Cd options AHC_SCBPAGING_ENABLE
|
|
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.Pp
|
|
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To enable tagged queueing:
|
|
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.Cd options AHC_TAGENABLE
|
|
||||||
.Pp
|
|
||||||
To allow PCI adapters to use memory mapped I/O if enabled:
|
To allow PCI adapters to use memory mapped I/O if enabled:
|
||||||
.Cd options AHC_ALLOW_MEMIO
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.Cd options AHC_ALLOW_MEMIO
|
||||||
.Pp
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.Pp
|
||||||
@ -55,59 +49,49 @@ For one or more SCSI busses:
|
|||||||
.Sh DESCRIPTION
|
.Sh DESCRIPTION
|
||||||
This driver provides access to the
|
This driver provides access to the
|
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.Tn SCSI
|
.Tn SCSI
|
||||||
bus(es) connected to Adaptec
|
bus(es) connected to Adaptec
|
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274x, 284x, 2940, 3940, or controllers based on the
|
|
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.Tn AIC7770,
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.Tn AIC7770,
|
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.Tn AIC7850,
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.Tn AIC7850,
|
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.Tn AIC7860,
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.Tn AIC7860,
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.Tn AIC7870,
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.Tn AIC7870,
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||||||
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.Tn AIC7880,
|
||||||
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.Tn AIC7890,
|
||||||
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.Tn AIC7891,
|
||||||
|
.Tn AIC7895,
|
||||||
|
.Tn AIC7896,
|
||||||
or
|
or
|
||||||
.Tn AIC7880
|
.Tn AIC7897
|
||||||
host adapter chips.
|
host adapter chips.
|
||||||
Features include support for twin and wide busses,
|
These chips are found on many motherboards as well as the following
|
||||||
ultra
|
Adaptec SCSI controller cards:
|
||||||
.Tn SCSI,
|
.Tn 274X(W),
|
||||||
two active commands at a time per non-tagged queueing target,
|
.Tn 274X(T),
|
||||||
tagged queuing,
|
.Tn 284X,
|
||||||
|
.Tn 2920C,
|
||||||
|
.Tn 2940,
|
||||||
|
.Tn 2940U,
|
||||||
|
.Tn 2940AU,
|
||||||
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.Tn 2940UW,
|
||||||
|
.Tn 2940UW Dual,
|
||||||
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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 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,
|
||||||
|
.Tn 3940U2W,
|
||||||
|
and
|
||||||
|
.Tn 3985.
|
||||||
|
.Pp
|
||||||
|
Driver features include support for twin and wide busses,
|
||||||
|
fast, ultra and ultra2 synchronous transfers depending on controller type,
|
||||||
|
tagged queueing,
|
||||||
and SCB paging.
|
and SCB paging.
|
||||||
.Pp
|
.Pp
|
||||||
The number of concurrent transactions allowed is chip dependent
|
Memory mapped I/O can be enabled for PCI devices with the
|
||||||
and ranges from 3 to 16.
|
|
||||||
On PCI adapters,
|
|
||||||
this number can be increased with the SCB paging option.
|
|
||||||
SCB paging implements an algorithm to 'page-out' transactions
|
|
||||||
that are in the disconnected state so that the freed space in
|
|
||||||
the controller's memory can be used to start additional transactions.
|
|
||||||
On the aic7880 and aic7870,
|
|
||||||
this increases the maximum number of outstanding transactions from 16 to 255.
|
|
||||||
On the aic7850 and aic7860 controllers, this maximum rises from 3 to 8.
|
|
||||||
During the hardware probe,
|
|
||||||
a diagnostic showing the ratio of hardware supported 'slots' to number
|
|
||||||
of transactions is printed.
|
|
||||||
SCB paging is enabled with the
|
|
||||||
.Dq Dv AHC_SCBPAGING_ENABLE
|
|
||||||
configuration option.
|
|
||||||
This option will likely be removed and become the default behavior for
|
|
||||||
adapters that support it,
|
|
||||||
in the near future.
|
|
||||||
.Pp
|
|
||||||
Tagged queueing is enabled with the
|
|
||||||
.Dq Dv AHC_TAGENABLE
|
|
||||||
configuration option.
|
|
||||||
Tagged queueing allows multiple transactions to be queued at the device
|
|
||||||
level instead of the host level,
|
|
||||||
allowing the device to re-order I/O to minimize seeks,
|
|
||||||
seek distance,
|
|
||||||
and to increase throughput.
|
|
||||||
Tagged queueing can have a significant impact on performance for seek
|
|
||||||
bound applications and should be enabled for most configurations.
|
|
||||||
Unfortunately, some devices that claim to support tagged queueing fail
|
|
||||||
miserably when it is used.
|
|
||||||
The only reason tagged queueing remains as a controller option is as a
|
|
||||||
stop gap measure until a mechanism to detect these broken devices and to
|
|
||||||
control this feature on a per device basis is in place.
|
|
||||||
.Pp
|
|
||||||
Memory mapped I/O can be enabled with the
|
|
||||||
.Dq Dv AHC_ALLOW_MEMIO
|
.Dq Dv AHC_ALLOW_MEMIO
|
||||||
configuration option.
|
configuration option.
|
||||||
Memory mapped I/O is more efficient than the alternative, programmed I/O.
|
Memory mapped I/O is more efficient than the alternative, programmed I/O.
|
||||||
@ -139,7 +123,12 @@ must be enabled for
|
|||||||
adaptors. This includes synchronous/asynchronous transfers,
|
adaptors. This includes synchronous/asynchronous transfers,
|
||||||
maximum synchronous negotiation rate,
|
maximum synchronous negotiation rate,
|
||||||
disconnection,
|
disconnection,
|
||||||
and the host adapter's SCSI ID.
|
the host adapter's SCSI ID,
|
||||||
|
and,
|
||||||
|
in the case of
|
||||||
|
.Tn EISA
|
||||||
|
Twin Channel controllers,
|
||||||
|
the primary channel selection.
|
||||||
.Pp
|
.Pp
|
||||||
Note that I/O addresses are determined automatically by the probe routines,
|
Note that I/O addresses are determined automatically by the probe routines,
|
||||||
but care should be taken when using a 284x
|
but care should be taken when using a 284x
|
||||||
@ -151,35 +140,110 @@ system. Ensure that the jumpers setting the I/O area for the 284x match the
|
|||||||
slot into which the card is inserted to prevent conflicts with other
|
slot into which the card is inserted to prevent conflicts with other
|
||||||
.Tn EISA
|
.Tn EISA
|
||||||
cards.
|
cards.
|
||||||
|
.Pp
|
||||||
|
Performance and feature sets vary throughout the aic7xxx product line.
|
||||||
|
The following table provides a comparison of the different chips supported
|
||||||
|
by the
|
||||||
|
.Nm
|
||||||
|
driver. Note that wide and twin channel features, although always supported
|
||||||
|
by a particular chip, may be disabled in a particular motherboard or card
|
||||||
|
design.
|
||||||
|
.Pp
|
||||||
|
.Bd -filled -offset indent
|
||||||
|
.Bl -column "aic7770 " "10 " "EISA/VL " "10MHz " "16bit " "SCBs " Features
|
||||||
|
.Em "Chip MIPS Bus MaxSync MaxWidth SCBs Features"
|
||||||
|
aic7770 10 EISA/VL 10MHz 16Bit 4 1
|
||||||
|
aic7850 10 PCI/32 10MHz 8Bit 3
|
||||||
|
aic7860 10 PCI/32 20MHz 8Bit 3
|
||||||
|
aic7870 10 PCI/32 10MHz 16Bit 16
|
||||||
|
aic7880 10 PCI/32 20MHz 16Bit 16
|
||||||
|
aic7890 20 PCI/32 40MHz 16Bit 16 3 4 5 6 7
|
||||||
|
aic7891 20 PCI/64 40MHz 16Bit 16 3 4 5 6 7
|
||||||
|
aic7895 15 PCI/32 20MHz 16Bit 16 2 3 4 5
|
||||||
|
aic7896 20 PCI/32 40MHz 16Bit 16 2 3 4 5 6 7
|
||||||
|
aic7897 20 PCI/64 40MHz 16Bit 16 2 3 4 5 6 7
|
||||||
|
.El
|
||||||
|
.Pp
|
||||||
|
.Bl -enum -compact
|
||||||
|
.It
|
||||||
|
Multiplexed Twin Channel Device - One controller servicing two busses.
|
||||||
|
.It
|
||||||
|
Multi-function Twin Channel Device - Two controllers on one chip.
|
||||||
|
.It
|
||||||
|
Command Channel Secondary DMA Engine - Allows scatter gather list and
|
||||||
|
SCB prefetch.
|
||||||
|
.It
|
||||||
|
64 Byte SCB Support - SCSI CDB is embedded in the SCB to eliminate an extra DMA.
|
||||||
|
.It
|
||||||
|
Block Move Instruction Support - Doubles the speed of certain sequencer
|
||||||
|
operations.
|
||||||
|
.It
|
||||||
|
.Sq Bayonet
|
||||||
|
style Scatter Gather Engine - Improves S/G prefetch performance.
|
||||||
|
.It
|
||||||
|
Queueing Registers - Allows queueing of new transactions without pausing the
|
||||||
|
sequencer.
|
||||||
|
.El
|
||||||
|
.Ed
|
||||||
|
.Pp
|
||||||
|
|
||||||
|
.Sh SCSI CONTROL BLOCKS (SCBs)
|
||||||
|
Every transaction sent to a device on the SCSI bus is assigned a
|
||||||
|
.Sq SCSI Control Block
|
||||||
|
(SCB). The SCB contains all of the information required by the
|
||||||
|
controller to process a transaction. The chip feature table lists
|
||||||
|
the number of SCBs that can be stored in on chip memory. All chips
|
||||||
|
with model numbers greater than or equal to 7870 allow for the on chip
|
||||||
|
SCB space to be augmented with external SRAM up to a maximum of 255 SCBs.
|
||||||
|
Very few Adaptec controller have external SRAM.
|
||||||
|
|
||||||
|
If external SRAM is not available, SCBs are a limited resource and
|
||||||
|
using them in a straight forward manner would only allow us to
|
||||||
|
keep as many transactions as there are SCBs outstanding at a time.
|
||||||
|
This would not allow enough concurrency to fully utilize the SCSI
|
||||||
|
bus and it's devices. The solution to this problem is
|
||||||
|
.Em SCB Paging ,
|
||||||
|
a concept similar to memory paging. SCB paging takes advantage of
|
||||||
|
the fact that devices usually disconnect from the SCSI bus for long
|
||||||
|
periods of time without talking to the controller. The SCBs
|
||||||
|
for disconnected transactions are only of use to the controller
|
||||||
|
when the transfer is resumed. When the host queues another transaction
|
||||||
|
for the controller to execute, the controller firmware will use a
|
||||||
|
free SCB if one is available. Otherwise, the state of the most recently
|
||||||
|
disconnected (and therefor most likely to stay disconnected) SCB is
|
||||||
|
saved, via dma, to host memory, and the local SCB reused to start
|
||||||
|
the new transaction. This allows the controller to queue up to
|
||||||
|
255 transactions regardless of the amount of SCB space. Since the
|
||||||
|
local SCB space serves as a cache for disconnected transactions, the
|
||||||
|
more SCB space available, the less host bus traffic consumed saving
|
||||||
|
and restoring SCB data.
|
||||||
.Sh BUGS
|
.Sh BUGS
|
||||||
Some Quantum drives (at least the Empire 2100 and 1080s) will not run on an
|
Some Quantum drives (at least the Empire 2100 and 1080s) will not run on an
|
||||||
.Tn AIC7870
|
.Tn AIC7870
|
||||||
Rev B in synchronous mode at 10MHz. Controllers with this problem have a
|
Rev B in synchronous mode at 10MHz. Controllers with this problem have a
|
||||||
42 MHz clock crystal on them and run slightly above 10MHz. This causes the
|
42 MHz clock crystal on them and run slightly above 10MHz. This confuses
|
||||||
drive much confusion. Setting a maximum synchronous negotiation rate of 8MHz
|
the drive and hangs the bus. Setting a maximum synchronous negotiation rate
|
||||||
in the
|
of 8MHz in the
|
||||||
.Tn SCSI-Select
|
.Tn SCSI-Select
|
||||||
utility
|
utility
|
||||||
will allow normal function.
|
will allow normal operation.
|
||||||
.Sh SEE ALSO
|
.Sh SEE ALSO
|
||||||
.Xr aha 4 ,
|
.Xr aha 4 ,
|
||||||
.Xr ahb 4 ,
|
.Xr ahb 4 ,
|
||||||
.Xr cd 4 ,
|
.Xr cd 4 ,
|
||||||
.Xr scsi 4 ,
|
.Xr scsi 4 ,
|
||||||
.Xr sd 4 ,
|
.Xr da 4 ,
|
||||||
.Xr st 4
|
.Xr sa 4
|
||||||
.Sh AUTHORS
|
.Sh AUTHORS
|
||||||
The
|
The
|
||||||
.Nm
|
.Nm
|
||||||
driver was written by
|
driver, the
|
||||||
.An Justin Gibbs .
|
|
||||||
The
|
|
||||||
.Tn AIC7xxx
|
.Tn AIC7xxx
|
||||||
sequencer-code assembler was
|
sequencer-code assember,
|
||||||
written by
|
and the firmware running on the aic7xxx chips was written by
|
||||||
.An John Aycock .
|
.An Justin T. Gibbs .
|
||||||
.Sh HISTORY
|
.Sh HISTORY
|
||||||
The
|
The
|
||||||
.Nm
|
.Nm
|
||||||
driver appeared in
|
driver appeared in
|
||||||
.Fx 2.1 .
|
.Fx 2.0 .
|
||||||
|
|||||||
Loading…
x
Reference in New Issue
Block a user