2010-12-14  Colin Watson  <cjwatson@ubuntu.com>

	Preferred resolution detection for VBE.

	* grub-core/video/video.c (grub_video_edid_checksum): New function.
	* grub-core/video/i386/pc/vbe.c (grub_vbe_bios_get_flat_panel_info):
	Likewise.
	(grub_vbe_bios_get_ddc_capabilities): Likewise.
	(grub_vbe_bios_read_edid): Likewise.
	(grub_vbe_get_preferred_mode): Likewise.  Try EDID followed by the
	Flat Panel extension, in line with the X.org VESA driver.
	(grub_video_vbe_setup): When the mode is "auto", try to get the
	preferred mode from VBE, and use the largest mode that is no larger
	than the preferred mode (some BIOSes expose a preferred mode that is
	not in their mode list!).  If this fails, fall back to 640x480 as a
	safe conservative choice.
	* include/grub/video.h (struct grub_vbe_edid_info): New structure.
	(grub_video_edid_checksum): Add prototype.
	* include/grub/i386/pc/vbe.h (struct grub_vbe_flat_panel_info): New
	structure.
	(grub_vbe_bios_get_flat_panel_info): Add prototype.
	(grub_vbe_bios_get_ddc_capabilities): Likewise.
	(grub_vbe_bios_read_edid): Likewise.

	* util/grub.d/00_header.in (GRUB_GFXMODE): Default to "auto".  This
	is more appropriate on a wider range of platforms than 640x480.