Motorola MVME197LE manual Disk I/O via 197Bug System Calls, Dskcfig

Debugger General Information

Disk I/O via 197Bug System Calls

All operations that actually access the disk are done directly or indirectly by 197Bug TRAP #496 system calls. (The command-level disk operations provide

3a convenient way of using these system calls without writing and executing a program).

The following system calls are provided to allow user programs to do disk I/O:

.DSKRD	Disk read. System call to read blocks from a disk into
	memory.
.DSKWR	Disk write. System call to write blocks from memory onto a
	disk.
.DSKCFIG	Disk configure. This function allows the user to change the
	configuration of the specified device.
.DSKFMT	Disk format. This function allows the user to send a format
	command to the specified device.
.DSKCTRL	Disk control. This function is used to implement any special
	device control functions that cannot be accommodated easily
	with any of the other disk functions.

Refer to the MVME197BUG 197Bug Debugging Package User’s Manual for information on using these and other system calls.

To perform a disk operation, 197Bug must eventually present a particular disk controller module with a controller command packet which has been especially prepared for that type of controller module. (This is accomplished in the respective controller driver module). A command packet for one type of controller module usually does not have the same format as a command packet for a different type of module. The system call facilities which do disk I/O accept a generalized (controller-independent) packet format as an argument, and translate it into a controller-specific packet, which is then sent to the specified device. Refer to the system call descriptions found in the MVME197BUG 197Bug Debugging Package User’s Manual for details on the format and construction of these standardized “user” packets.

The packets which a controller module expects to be given vary from controller to controller. The disk driver module for the particular hardware module (board) must take the standardized packet given to a trap function and create a new packet which is specifically tailored for the disk drive controller it is sent to. Refer to documentation on the particular controller module for the format of its packets, and for using the IOC command.

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