| ahc.4 (18610) | ahc.4 (22897) |
|---|---|
| 1.\" | 1.\" |
| 2.\" Copyright (c) 1995, 1996 | 2.\" Copyright (c) 1995, 1996, 1997 |
| 3.\" Justin T. Gibbs. All rights reserved. 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice, this list of conditions and the following disclaimer. 10.\" 2. Redistributions in binary form must reproduce the above copyright --- 24 unchanged lines hidden (view full) --- 35For one or more VL/EISA cards: 36.Cd controller eisa0 37.Cd controller ahc0 38.Pp 39For one or more PCI cards: 40.Cd controller pci0 41.Cd controller ahc0 42.Pp | 3.\" Justin T. Gibbs. All rights reserved. 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice, this list of conditions and the following disclaimer. 10.\" 2. Redistributions in binary form must reproduce the above copyright --- 24 unchanged lines hidden (view full) --- 35For one or more VL/EISA cards: 36.Cd controller eisa0 37.Cd controller ahc0 38.Pp 39For one or more PCI cards: 40.Cd controller pci0 41.Cd controller ahc0 42.Pp |
| 43To enable SCB paging: 44.Cd options AHC_SCBPAGING_ENABLE 45.Pp |
|
| 43To enable tagged queueing: 44.Cd options AHC_TAGENABLE 45.Pp | 46To enable tagged queueing: 47.Cd options AHC_TAGENABLE 48.Pp |
| 46To enable SCB paging: 47.Cd options AHC_SCBPAGING_ENABLE | 49To allow PCI adapters to use memory mapped I/O if enabled: 50.Cd options AHC_ALLOW_MEMIO |
| 48.Pp 49For one or more SCSI busses: 50.Cd controller scbus0 at ahc0 51.Sh DESCRIPTION 52This driver provides access to the 53.Tn SCSI | 51.Pp 52For one or more SCSI busses: 53.Cd controller scbus0 at ahc0 54.Sh DESCRIPTION 55This driver provides access to the 56.Tn SCSI |
| 54bus connected to an Adaptec | 57bus(es) connected to Adaptec |
| 55274x, 284x, 2940, 3940, or controllers based on the 56.Tn AIC7770, 57.Tn AIC7850, 58.Tn AIC7860, 59.Tn AIC7870, 60or 61.Tn AIC7880 62host adapter chips. 63Features include support for twin and wide busses, 64ultra 65.Tn SCSI, 66two active commands at a time per non-tagged queueing target, 67tagged queuing, | 58274x, 284x, 2940, 3940, or controllers based on the 59.Tn AIC7770, 60.Tn AIC7850, 61.Tn AIC7860, 62.Tn AIC7870, 63or 64.Tn AIC7880 65host adapter chips. 66Features include support for twin and wide busses, 67ultra 68.Tn SCSI, 69two active commands at a time per non-tagged queueing target, 70tagged queuing, |
| 68and SCB paging which allows up to 255 active commands on all adapters 69except those using 70.Tn AIC7770 71chips prior to revision E. | 71and SCB paging. 72.Pp 73The number of concurrent transactions allowed is chip dependent 74and ranges from 3 to 16. 75On PCI adapters, 76this number can be increased with the SCB paging option. 77SCB paging implements an algorithm to 'page-out' transactions 78that are in the disconnected state so that the freed space in 79the controller's memory can be used to start additional transactions. 80On the aic7880 and aic7870, 81this increases the maximum number of outstanding transactions from 16 to 255. 82On the aic7850 and aic7860 controllers, this maximum rises from 3 to 8. 83During the hardware probe, 84a diagnostic showing the ratio of hardware supported 'slots' to number 85of transactions is printed. 86SCB paging is enabled with the 87.Dq Dv AHC_SCBPAGING_ENABLE 88configuration option. 89This option will likely be removed and become the default behavior for 90adapters that support it, 91in the near future. 92.Pp |
| 72Tagged queueing is enabled with the 73.Dq Dv AHC_TAGENABLE 74configuration option. | 93Tagged queueing is enabled with the 94.Dq Dv AHC_TAGENABLE 95configuration option. |
| 75SCB paging is enabled with the 76.Dq Dv AHC_SCBPAGING_ENABLE | 96Tagged queueing allows multiple transactions to be queued at the device 97level instead of the host level, 98allowing the device to re-order I/O to minimize seeks, 99seek distance, 100and to increase throughput. 101Tagged queueing can have a significant impact on performance for seek 102bound applications and should be enabled for most configurations. 103Unfortunantly, some devices that claim to support tagged queueing fail 104miserable when it is used. 105The only reason tagged queueing remains as a controller option is as a 106stop gap measure until a mechanism to detect these broken devices and to 107control this feature on a per device basis is in place. 108.Pp 109Memory mapped I/O can be enabled with the 110.Dq Dv AHC_ALLOW_MEMIO |
| 77configuration option. | 111configuration option. |
| 112Memory mapped I/O is more efficient than the alternative, programmed I/O. 113Most PCI BIOSes will map devices so that either technique for communicating 114with the card is availible. 115In some cases, 116usually when the PCI device is sitting behind a PCI->PCI bridge, 117the BIOS fails to properly initialize the chip for memory mapped I/O. 118The symptom of this problem is usually a system hang if memory mapped I/O 119is attempted. 120Most modern motherboards perform the initialization correctly and work fine 121with this option enabled. |
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| 78.Pp 79Per target configuration performed in the 80.Tn SCSI-Select 81menu, accesible at boot 82in 83.No non- Ns Tn EISA | 122.Pp 123Per target configuration performed in the 124.Tn SCSI-Select 125menu, accesible at boot 126in 127.No non- Ns Tn EISA |
| 84models or through an | 128models, 129or through an |
| 85.Tn EISA 86configuration utility for 87.Tn EISA 88models, 89is honored by this driver with the stipulation that the 90.Tn BIOS 91must be enabled for 92.Tn EISA --- 11 unchanged lines hidden (view full) --- 104.Tn EISA 105slot into which the card is inserted to prevent conflicts with other 106.Tn EISA 107cards. 108.Sh BUGS 109Some Quantum drives (at least the Empire 2100 and 1080s) will not run on an 110.Tn AIC7870 111Rev B in synchronous mode at 10MHz. Controllers with this problem have a | 130.Tn EISA 131configuration utility for 132.Tn EISA 133models, 134is honored by this driver with the stipulation that the 135.Tn BIOS 136must be enabled for 137.Tn EISA --- 11 unchanged lines hidden (view full) --- 149.Tn EISA 150slot into which the card is inserted to prevent conflicts with other 151.Tn EISA 152cards. 153.Sh BUGS 154Some Quantum drives (at least the Empire 2100 and 1080s) will not run on an 155.Tn AIC7870 156Rev B in synchronous mode at 10MHz. Controllers with this problem have a |
| 11242 MHz clock crystal on them and run slightly above 10MHz, causing the | 15742 MHz clock crystal on them and run slightly above 10MHz. This causes the |
| 113drive much confusion. Setting a maximum synchronous negotiation rate of 8MHz 114in the 115.Tn SCSI-Select 116utility 117will allow normal function. | 158drive much confusion. Setting a maximum synchronous negotiation rate of 8MHz 159in the 160.Tn SCSI-Select 161utility 162will allow normal function. |
| 118.Pp 119The code to perform SCB paging doesn't work properly, don't use this option 120at this time. | |
| 121.Sh SEE ALSO 122.Xr aha 4 , 123.Xr ahb 4 , 124.Xr cd 4 , 125.Xr scsi 4 , 126.Xr sd 4 , 127.Xr st 4 128.Sh AUTHOR 129The 130.Nm 131driver was written by Justin Gibbs. The 132.Tn AIC7xxx 133sequencer-code assembler was 134written by John Aycock. 135.Sh HISTORY 136The 137.Nm 138driver appeared in 139.Fx 2.1 . | 163.Sh SEE ALSO 164.Xr aha 4 , 165.Xr ahb 4 , 166.Xr cd 4 , 167.Xr scsi 4 , 168.Xr sd 4 , 169.Xr st 4 170.Sh AUTHOR 171The 172.Nm 173driver was written by Justin Gibbs. The 174.Tn AIC7xxx 175sequencer-code assembler was 176written by John Aycock. 177.Sh HISTORY 178The 179.Nm 180driver appeared in 181.Fx 2.1 . |