Power Switch Off To On; On To Off (Os Absent); On To Off (Os Present); On To Sleep (Acpi) - Intel SE7520JR2 Technical Manual

System BIOS
The BIOS supports a control panel sleep button. The sleep button may not be provided on all
control panel designs. On systems where the sleep button is optional, a system configuration
option will be provided to enable or disable the sleep button. The ACPI tables will be updated to
indicate the presence or absence of the sleep button. Removal of the sleep button does not
prevent an ACPI OS from entering a sleep state.
The sleep button has no effect unless an operating system is running. If the OS is running,
pressing the sleep button causes an event. The OS will cause the system to transition to the
appropriate ACPI system state depending on the current user settings.
The platform supports a control panel reset button. The reset button is a request that is
forwarded by the mBMC to the chipset. The BIOS does not affect the behavior of the reset
button.
The BIOS supports a control panel NMI button. The NMI button may not be provided on all
control panel designs. The NMI button is a request that causes the mBMC to generate an NMI
(non-maskable interrupt). The NMI is captured by the BIOS during Boot Services time or the
OS during Runtime. The BIOS will simply halt the system upon detection of the NMI.
4.9.2.2

Power Switch Off to On

The chipset may be configured to generate wakeup events for several different system events:
Wake on LAN, PCI Power Management Interrupt (PMI), and Real Time Clock Alarm are
examples of these events. The operating system will program the wake sources before
shutdown. A transition from either source results in the mBMC starting the power-up sequence.
Since the processors are not executing, the BIOS does not participate in this sequence. The
hardware receives power good and reset from the mBMC and then transitions to an ON state.
4.9.2.3

On to Off (OS absent)

The SCI interrupt is masked. The firmware polls the power button status bit in the ACPI
hardware registers and sets the state of the machine in the chipset to the OFF state. The
mBMC monitors power state signals from the chipset and de-asserts PS_PWR_ON to the
power supply. As a safety mechanism, the mBMC automatically powers off the system in 4-5
seconds if the BIOS fails to service the request.
4.9.2.4

On to Off (OS present)

If an operating system is loaded, the power button generates a request (via SCI) to the OS to
shutdown the system. The OS retains control of the system and OS policy determines what
sleep state (if any) the system transitions into.
4.9.2.5

On to Sleep (ACPI)

If an operating system is loaded, the sleep button generates a request (via SCI) to the OS to
place the system in "sleep" mode. The OS retains control of the system and OS policy
determines what sleep state (if any) the system transitions into.
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C78844-002
Intel® Server Board SE7520JR2
Revision 1.0