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Debugger General Information
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Device Probe Function
A device probe with entry into the device descriptor table is done
whenever a specified device is accessed; i.e., when system calls
.DSKRD, .DSKWR, .DSKCFIG, .DSKFMT, and .DSKCTRL, and
debugger commands
BH, BO, IOC, IOP, IOT, MAR, and MAW are
used.
The device probe mechanism utilizes the SCSI commands Inquiry
and Mode Sense. If the specified controller is non-SCSI, the probe
simply returns a status of ‘‘device present and unknown’’. The
device probe makes an entry into the device descriptor table with
the pertinent data. After an entry has been made, the next time a
probe is done it simply returns with ‘‘device present’’ status
(pointer to the device descriptor).
Disk I/O via 162Bug Commands
These following 162Bug commands are provided for disk I/O.
Detailed instructions for their use are found in the Debugging
Package for Motorola 68K CISC CPUs User's Manual. When a
command is issued to a particular controller LUN and device LUN,
these LUNs are remembered by 162Bug so that the next disk
command defaults to use the same controller and device.
IOI (Input/Output Inquiry)
This command is used to probe the system for all possible
CLUN/DLUN combinations and display inquiry data for devices
which support it. The device descriptor table only has space for 16
device descriptors; with the
IOI command, you can view the table
and clear it if necessary.
IOP (Physical I/O to Disk)
IOP allows you to read or write blocks of data, or to format the
specified device in a certain way.
IOP creates a command packet
from the arguments you have specified, and then invokes the
proper system call function to carry out the operation.
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