*grep*
$ git grep VIDEO_COREBOOT
config/u-boot/amd64coreboot/config/default:CONFIG_VIDEO_COREBOOT=y
config/u-boot/i386coreboot/config/default:CONFIG_VIDEO_COREBOOT=y
$ git grep VIDEO_COREBOOT
arch/x86/cpu/coreboot/Kconfig: imply VIDEO_COREBOOT
drivers/video/Kconfig:config VIDEO_COREBOOT
drivers/video/Makefile:obj-$(CONFIG_VIDEO_COREBOOT) += coreboot.o
$ find -type f -name "coreboot.c"
./board/coreboot/coreboot/coreboot.c
./arch/x86/cpu/coreboot/coreboot.c
./drivers/video/coreboot.c