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Update the section on device wiring to match how things are done in 5.x.

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This commit is contained in:
Scott Long 2004-06-24 04:05:08 +00:00
parent 2220907b6e
commit 9ff0046621
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=131026
1 changed files with 39 additions and 16 deletions
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55
share/man/man4/scsi.4
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@ -159,23 +159,46 @@ so they appear as a particular device unit or
.Em counted
so that they appear as the next available unused unit.
.Pp
To configure a driver in the kernel without wiring down the device use a
config line similar to
.Cd "device ch0"
to include the changer driver.
Units are wired down by setting kernel environment hints.
This is usually done either interactively from the loader, or automatically via the
.Pa /boot/device.hints
file. The basic syntax is:
.Bd -literal -offset indent
hint.device.unit.property="value"
.Ed
.Pp
To wire down a unit use a config line similar to
.Cd "device ch1 at scbus0 target 4 unit 0"
to assign changer 1 as the changer with SCSI ID 4,
SCSI logical unit 0 on SCSI bus 0.
Individual scbuses can be wired down to specific controllers with
a config line similar to
.Cd "device scbus0 at ahc0"
which assigns scsi bus 0 to the first unit using the ahc driver.
For controllers supporting more than one bus,
the particular bus can be specified as in
.Cd "device scbus3 at ahc1 bus 1"
which assigns scbus 1 to the second bus probed on the ahc1 device.
Individual scsi bus numbers can be wired down to specific controllers with
a config line similar to the following:
.Bd -literal -offset indent
hint.scbus.0.at="ahd1"
.Ed
.Pp
This assigns scsi bus number 0 to the
.Em ahd1
driver instance.
For controllers supporting more than one bus, a particular bus can be assigned
as follows:
.Bd -literal -offset indent
hint.scbus.0.at="ahc1"
hint.scbus.0.bus="1"
.Ed
.Pp
This assigns scsi bus 0 to the bus 1 instance on
.Em ahc0 .
Peripheral drivers can be wired to a specific bus, target, and lun as so:
.Bd -literal -offset indent
hint.da.0.at="scbus0"
hint.da.0.target="0"
hint.da.0.unit="0"
.Ed
.Pp
This assigns
.Em da0
to target 0, unit (lun) 0 of scbus 0.
Omitting the target or unit hints will instruct CAM to treat them as wildcards
and use the first respective counted instances.
These examples can be combined together to allow a peripheral device to be
wired to any particular controller, bus, target, and/or unit instance.
.Pp
When you have a mixture of wired down and counted devices then the
counting begins with the first non-wired down unit for a particular