Module Name: src
Committed By: wiz
Date: Mon May 4 19:45:51 UTC 2009
Modified Files:
src/share/man/man4: ahc.4
Log Message:
New sentence, new line.
To generate a diff of this commit:
cvs rdiff -u -r1.32 -r1.33 src/share/man/man4/ahc.4
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/share/man/man4/ahc.4
diff -u src/share/man/man4/ahc.4:1.32 src/share/man/man4/ahc.4:1.33
--- src/share/man/man4/ahc.4:1.32 Fri Apr 10 15:05:06 2009
+++ src/share/man/man4/ahc.4 Mon May 4 19:45:51 2009
@@ -1,4 +1,4 @@
-.\" $NetBSD: ahc.4,v 1.32 2009/04/10 15:05:06 joerg Exp $
+.\" $NetBSD: ahc.4,v 1.33 2009/05/04 19:45:51 wiz Exp $
.\"
.\" Copyright (c) 1995, 1996, 1997, 1998, 2000
.\" Justin T. Gibbs. All rights reserved.
@@ -162,7 +162,8 @@
.\" Individual controllers may be configured to operate in the target role
.\" through the
.\" .Dq Dv AHC_TMODE_ENABLE
-.\" configuration option. The value assigned to this option should be a bitmap
+.\" configuration option.
+.\" The value assigned to this option should be a bitmap
.\" of all units where target mode is desired.
.\" For example, a value of 0x25, would enable target mode on units 0, 2, and 5.
.\" .Pp
@@ -202,7 +203,8 @@
.Pq Tn VESA No local bus controller
in an
.Tn EISA
-system. The jumpers setting the I/O area for the 284x should match the
+system.
+The jumpers setting the I/O area for the 284x should match the
.Tn EISA
slot into which the card is inserted to prevent conflicts with other
.Tn EISA
@@ -212,9 +214,10 @@
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.
+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
.Bl -column "aic7895c" "MIPS" "EISA/VL" "MaxSync" "MaxWidth" "SCBs" "2 3 4 5 6 7 8"
.It Sy Chip Ta Sy MIPS Ta Sy Bus Ta Sy MaxSync Ta Sy MaxWidth Ta Sy SCBs Ta Sy Features
@@ -394,11 +397,14 @@
.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.
+(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 configurations have external SRAM.
.Pp
If external SRAM is not available, SCBs are a limited resource.
@@ -408,20 +414,23 @@
requires much more concurrency.
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.
+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 SEE ALSO
.Xr aha 4 ,
.Xr ahb 4 ,
@@ -456,23 +465,26 @@
.Tn Quantum
drives (at least the Empire 2100 and 1080s) will not run on an
.Tn AIC7870
-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 confuses
-the drive and hangs the bus. Setting a maximum synchronous negotiation rate
-of 8MHz in the
+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 confuses the drive and hangs the bus.
+Setting a maximum synchronous negotiation rate of 8MHz in the
.Tn SCSI-Select
utility will allow normal operation.
.Pp
.\" Although the Ultra2 and Ultra160 products have sufficient instruction
.\" ram space to support both the initiator and target roles concurrently,
.\" this configuration is disabled in favor of allowing the target role
-.\" to respond on multiple target ids. A method for configuring dual
+.\" to respond on multiple target ids.
+.\" A method for configuring dual
.\" role mode should be provided.
.\" .Pp
.\" Tagged Queuing is not supported in target mode.
.\" .Pp
.\" Reselection in target mode fails to function correctly on all high
-.\" voltage differential boards as shipped by Adaptec. Information on
+.\" voltage differential boards as shipped by Adaptec.
+.\" Information on
.\" how to modify HVD board to work correctly in target mode is available
.\" from Adaptec.
Target mode is not supported on
