Kontron CP6002 IPMI - Manual (Page 17)

CP6002 IPMI Firmware User Guide
ID: 1039-1613, Rev. 2.0 Page 17
Normally the logical states “active” and “inactive” of a payload are identical to the physical
states “handle open” and “handle closed” or “payload power off” and “payload power on”.
If, however, power is switched on or off using IPMI chassis commands or the payload is shut
down by the OS, then the position of the Hot Swap Handle and the power state may become
asynchronous. In this case the blue LED is switched on indicating that the payload power is
switched off although the handle is closed. Such actions are not part of the Hot Swap process
and are governed by their own functionality which is not within the scope of this document.
6.2 The Hot Swap and Shut Down Processes
Hot Swap as defined here, is the purposely initiated process to remove and replace an active
board in a powered system. To accomplish this requires that the hot swap process provide for
an orderly transition of the payload from the active to inactive state and vice versa. This is nec-
essary to preclude improper system operation and possible loss of data. The CP6002 has all
the necessary features including hardware and IPMI software to support hot swapping. On the
software side, however, not all available OS’s support hot swapping, not even partially. Three
possible cases for hot swapping based on OS capabilities are described as follows.
Case 1: Involves an OS which does not support ACPI
After payload power on, the starting EFI will inform the Management Controller by sending the
IPMI command “Set ACPI Power State / Set Legacy on”. This means that a Hot Swap (opening
of the closed handle) shall immediately lead to payload power off by the Management
controller.
In this event, the application/operator is responsible for the termination of all payload processes
prior to initiating removal/replacement of the board to avoid improper operation or loss of data.
Case 2: Involves an OS which emulates ACPI support
An OS which does not really support ACPI, such as VxWorks, is able to obtain “Graceful Shut
Down” support from the Management Controller by performing in the following way.
After start up, such an OS must manipulate the chip set in a way that prevents an immediate
power off when the “power button” is logically activated.
Then it must send the IPMI command “Set ACPI Power State / S0/G0 working” to the Manage-
ment Controller to enable this to process later on an “S3/G2 soft off” command.
During application operation the system must cyclically read the “Hot Swap Sensor” (sensor
#0) using the IPMI command “Get Sensor Reading”. This allows the tracking of the board's
state. After the board has once reached “M-state” 4 (sensor reading is 10h) the leaving of this
announces that the handle was opened. Now the time has come to terminate all processes.
After all critical processes have been terminated, the OS must send the IPMI command “Set
ACPI Power State / S3/G2 soft off” to the Management Controller which will set the power off
immediately.
Case 3: Involves an OS which supports ACPI
When an OS is started which supports ACPI, the IPMI command “Set ACPI Power State /
S0/G0 working” is sent to the Management Controller. This indicates that the OS has repro-
grammed the chip set in such a manner that a “power button” signal does not lead to an imme-
diate power off but only causes an event that can be detected by the OS.