I-Bus 0818D, Руководство пользователя

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Chapter 6 – Platform Management Option
0818D User’s Guide 6-12
6.6.2 IPMI Command Interface Software
The IPMI Command Interface software module is accessible through
the RS232 port and the IPMB0 connection of the CMC board.
IPMI commands these interfaces are accepted serially and passed
on to the IPMI command interface of the controller chip by the
firmware.
The firmware will switch between the two interfaces to determine if
any activity is present, which means only one can be active an any
one time. Once one interface is locked in as the command
originator, the other interface may not receive a command until the
first command has been fully received.
Response messages will be sent to the requesting SBC only.
6.6.2.1 Packet Format
The packet format on the RS232 interface uses the standard Block
Transfer format as described in the IPMI 1.0 rev 1.1 specification
(section 9). The host must set a unique sequence number. The
response will use the same sequence number. The command buffer
must be no bigger then 36 bytes. None of Block Transfer status
registers or bits are used, only the packet format.
6.6.2.2 Timeouts
Inter-Byte Timeout: The timeout between successive bytes will be
set to 1 second.
SBC Exchange Timeout: The timeout between the end of receipt of
a request by the CMC to the end of receipt of a complete response
by the SBC will be set to 5 seconds.
Back-off Timeout: The time the SBC must wait if it detects any other
timeout is 6 seconds.
6.6.2.3 Watchdog Timer
Furthermore, the CMC controller chip enables its own internal
hardware watchdog timer, causing it to reset itself in case the
firmware does not actively refresh the timer. When this happens, the
CMC LED will be red for a moment while the self-test is performed.