Intel SE7501WV2 User Manual

Page of 169
BIOS 
Intel® Server Board SE7501WV2 TPS 
  
Revision 
1.0 
 
Intel reference number C25653-001 
114
6.36  System Limit Error 
The BMC monitors system operational limits. It manages the A/D converter, defining voltage 
and temperature limits as well as fan sensors and chassis intrusion. Any sensor values outside 
of specified limits are fully handled by BMC. The BIOS does not generate an SMI to the host 
processor for these types of system events.  
Refer to the SE7501WV2 Server Management External Architecture Specification for details on 
various sensors and how they are managed. 
6.37 Boot Event 
The BIOS downloads the system date and time to the BMC during POST and logs a boot event 
in the system event log. Software applications that parse the event log should not treat this boot 
event as an error. 
6.38  Fault Resilient Booting (FRB) 
The BIOS and firmware provides a feature to guarantee that the system boots, even if one or 
more processors fail during POST. The BMC contains two watchdog timers that can be 
configured to reset the system upon time-out.  
6.38.1 FRB3 
FRB3 refers to the FRB algorithm that detects whether the BSP is healthy enough to run BIOS 
at all.  The BMC starts the FRB3 timer when the system is powered up or hard reset.  The BIOS 
stops this timer in the power-on self test (POST) by asserting the FRB3 timer halt signal to the 
BMC.  This requires that the BSP actually runs BIOS code.  If the timer is not stopped within 5 
seconds, and it expires, the BMC disables the BSP, logs an FRB3 error event, chooses another 
BSP (from the set of non-failed processors), and resets the system.  FRB3 provides a check to 
verify that the selected BSP is not dead on start up and can actually run code. This process 
repeats until either the system boots without an FRB3 timeout, or all of the remaining 
processors have been disabled. At this point, if all the processors have been disabled, the BMC 
will attempt to boot the system on one processor at a time, irrespective of processor error 
history. This is called desperation mode. 
6.38.2 FRB2 
FRB2 refers to the level of FRB in which the BIOS uses the BMC watchdog timer to back up its 
operation during POST.  The BIOS configures the watchdog timer for approximately 6-10 
minutes indicating that the BIOS is using the timer for the FRB2 phase of operation. 
After BIOS has identified the BSP and saved that information, it will then check to see if the 
watchdog timer expired on the previous boot.  If so, it will store the Time Out Reason bits in a 
fixed CMOS location (token name = cmosWDTimerFailReason) for applications or a User 
Binary to examine and act upon.  Next, it sets the watchdog timer FRB2 timer use bit, loads the 
watchdog timer with the new timeout interval, and disables FRB3 using the FRB3 timer halt 
signal.  This sequence ensures that no gap exists in watchdog timer coverage between FRB3 
and FRB2. 
Note:  FRB2 is not supported when the BIOS is in Recovery Mode.