Motorola MVME166D2 用户手册

Debugger General Information

3-16

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).  

These following 166Bug 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 166Bug so 
that the next disk command defaults to use the same controller and device.  

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.  

 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.  

 allows you to change any configurable parameters and attributes of the 

device.  In addition, it allows you to see the controllers available in the system.