acpi_video_flags

This allows mode of video boot to be set during run time.

During S3 resume, hardware needs to be reinitialized. For most devices, this is easy, and kernel driver knows how to do it. Unfortunately there's one exception: video card. Those are usually initialized by BIOS, and kernel does not have enough information to boot video card. See Documentation/power/video.txt in kernel source tree for more info.