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Firmware Download and Configuration
Although the self
test~ diagnostic~
and bootstrap firmware are all resident in
ROM~
the operational firmware must be downloaded from the host into the
LANIC local memory. After the firmware is
downloaded~
control is passed to it
and the LANIC is ready to be configured. Configuration comprises the 82586
chip
configuration~
setting the station address. and initializing the command
response queues.
Firmware Download
The host initiates the downloading of firmware from system memory to the
LANIC local RAM. The LANIC performs the actual transfer via its DMA
facility. After the transfer. the LANIC computes the checksum of the data in
local RAM and compares it with the checksum computed by the host. This
ensures that the download firmware is transferred correctly. The entire
firmware may be downloaded via a sequence of download operations. The host
has full control of firmware operation and can suspend firmware execution at
any time and dump LANIC memory and hardware status to system memory.
Setting Station Address
The LANIC supports both globally and locally administered
~ddressing.
Globally
administered addressing is supported by a ROM on the LANIC that has a unique
48-bit address code. This address can be read by the host. Setting the station
address is accomplished by a process involving the Duplicate Address Check
(DAC) protocol. The host supplies the LANIC with a candidate station address.
The LANIC sends an Exchange Identification (XID) packet with this address in
the destihation field. If any node is using the same station address, it sends the
packet back to the LANIC. The LANIC waits for any response to come back
before establishing its station address. If the DAC protocol fails. the host is
notified to take further action.
Queue Initialization
Once operational. most of the communication between the host and the LANIC
is via a pair of queue structures in system memory. One
queue~
the Command
Queue (CQ). is used by the host to send commands to the LANIC. The other
queue. the Response Queue (RQ), is used by the LANIC to return status to the
host. Each queue is fixed in size with fixed-length entries. however these
parameters are programmable when the queues are configured by the host. The
head and tail pointers are stored in system memory along with each queue. The
host informs the LANIC of new entries in the CQ by means of the
READ_QUEUE command. The LANIC informs the host of new RQ entries by
means of the system interrupt facility.
Principles of Operation
3-4
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