Kontron CP6003-RC IPMI - Manual (Page 39)

CP6003-SA/RA/RC IPMI Firmware
ID 1045-5656, Rev. 2.0 Page 39
P R E L I M I N A R Y
12.2 The Hot Swap and Shutdown 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 CP6003-SA/RA/
RC has all the necessary features including hardware and IPMI software to support hot swap-
ping. On the software side, however, not all available OS’s support hot swapping, not even par-
tially. 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 uEFI BIOS will inform the IPMI 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 IPMI
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 IPMI controller by performing in the following way.
After start-up, such an OS must manipulate the chipset 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
IPMI 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 IPMI 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 IPMI controller. This indicates that the OS has repro-
grammed the chipset 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.
When the handle is opened, the IPMI controller asserts the “power button” signal to notify the
OS. The OS then shuts down all processes and afterwards causes the transmission of the IPMI
command Set ACPI Power State / S3/G2 soft off to the IPMI controller which then
switches the power off.