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Chapter 3 - MACSI Host Interface
60
Fetch offboard (FOB)
Setting this bit makes the Command Queue entry an offboard entry. Please see the following section for
details.
Fetch offboard in progress (FIP)
This bit is used internally by the controller. It’s value should not be used by the host driver.
IOPB Address
This field contains a pointer to the IOPB for the command being issued, and is specified as an offset, in bytes, from the
start of Short I/O space. The space occupied by the IOPB will be available for re-use as soon as the controller clears
the Go bit, indicating that the command has been received.
Command Tag
This field is returned unchanged to the host upon completion of the command, and may be used to uniquely identify
the returned command. Typically, the host driver would place a pointer to a control structure associated with the
command in this field. The controller does not use the value in this field in any way.
Work Queue Number
This field is not currently used, though the value entered will be returned to the host.
Offboard Command Queue Entry
The following fields are defined for an offboard Command Queue entry.
Table 3-7. Offboard Command Queue Entry
Queue Entry Control Register (QECR)
The QECR field in the offboard entry is identical to the onboard version, except that the Fetch Offboard bit is set.
Offboard Command Queue Entry
Offst 1514131211109876543210
0x00 Queue Entry Control Register
0x01 Dma Transfer Control Word
0x02 Host Address (MSW)
0x03 Host Address (LSW)
0x04 Offboard Transfer Length Work Queue Number
0x05 Reserved