CONFIG_ACPI_MCFG (not configurable)

modulename: pci_mcfg.ko

configname: CONFIG_ACPI_MCFG

Linux Kernel Configuration
└─>Power management and ACPI options
└─>ACPI (Advanced Configuration and Power Interface) Support
└─>ACPI_MCFG
In linux kernel since version 4.2 (release Date: 2015-08-30)  
source code:
drivers/acpi/pci_mcfg.c
depends
CONFIG_ACPI