Intel® Pentium® Silver and Intel® Celeron® Processors Datasheet, Volume 1
Virtual GPIO (vGPIO)
vGPIO is a special type of GPIO implemented in the PCH for a specific functionality. vGPIO is not a physical GPIO; the signal is not balled out on the package. Programming the vGPIO is similar to programming a physical GPIO.
The PCH implements vGPIO39 (in GPIO community 1), which is specifically used for SD card detection as an interrupt generation. If the PCH integrated SD card is utilized, in conjunction of the SD_CD# pin to be used as card detect, a physical GPIO pin is required for interrupt generation. vGPIO39 is intended to replace the need for this addition physical GPIO if desired. SW needs to program the vGPIO accordingly to enable this functionality.