Publication No. 500-657055-000 Rev. G
IPMI Firmware and OEM Extensions 67
B.5 BMC Functions
The Abaco IPMI firmware can perform some of the functions of a Baseboard Management Controller.
The firmware can send IPMI commands to other targets on the IPMB on behalf of the VMICPCI-7055/
CPCI-7055RC and return the responses to the VMICPCI-7055/CPCI-7055RC. It can also forward any
platform events it receives to the VMICPCI-7055/CPCI-7055RC.
B.5.1 IPMB Relay
This command allows the VMICPCI-7055/CPCI-7055RC, connected to the Zircon’s I
2
C1 bus, to have the
Zircon send a command on its I
2
C0 bus (which is connected to the IPMB pins on the backplane), and for
the Zircon to send the response to that command back to the VMICPCI-7055/CPCI-7055RC on I
2
C1.
NOTE
The Zircon will accept an IPMB Relay request on its I
2
C0 bus, but it will always send the response to the I
2
C1 bus. Therefore, any device
on the IPMB that sends an IPMB Relay request to the Zircon will not receive a response.
If the request is successfully sent, then the response will be the actual response from the target system,
with only a few header bytes changed to have it sent back to the VMICPCI-7055/CPCI-7055RC.
If the request cannot be relayed (due to a device not responding, or the Zircon is temporarily out of
memory), the response to this command will use the NetFn and Cmd for IPMB Relay, and a completion
code only.
Table B-20 NetFn 0x32, Cmd 0x00
B.5.2 Forwarding of Platform Events
A chassis may contain other IPMI devices, such as an alarm card, which will generate Platform Events.
The alarm card would send the event to the I
2
C slave address that was provided by a “Set Event
Receiver” command. The Abaco IPMI firmware will immediately acknowledge any Platform Event it
receives then forward the packet to the slave address provided by a “Set Platform Event Forwarding
Address” command.
The VMICPCI-7055/CPCI-7055RC should not send a response for the Platform Event to the Zircon nor to
the originating device, as the Zircon has already responded.
Software on the VMICPCI-7055/CPCI-7055RC should set the forwarding address first then use IPMB
relay to send a “Set Event Receiver” command to the alarm cards or other IPMI devices in the chassis.
Byte
Value
Data Field
Comments
Request-Data
1
XXh
[7:1] – Target slave
address
[0] – 0
2
XXh
[7:6] – 0
[5:0] – NetFn
3
XXh
[7:2] – 0
[1:0] – LUN
4
XXh
Command
5:N
XXh
Optional Data
Response-data 1
XXh
Completion code
2:N
XXh
Optional response
data
See examples below
