Intel® Pentium® Silver and Intel® Celeron® Processors Datasheet, Volume 1
GPIO Blink (BK) and Serial Blink (SBK)
Certain GPIOs are capable of supporting blink and serial blink, indicated as BK and SBK respectively in the GPIO Signals table above. The BK and SBK are implemented as native functions muxed on the selected GPIOs. To enable BK or SBK on a GPIO having the capability, BIOS needs to select the assigned native function for BK or SBK on the GPIO.