VESA BIOS Extensions

VESA BIOS Extensions (VBE) is a VESA standard, currently at version 3, that defines the interface that can be used by software to access compliant video boards at high resolutions and bit depths. This is opposed to the "traditional" int 10h BIOS calls, which are limited to resolutions of 640×480 pixels with 16 color (4-bit) depth or less.

VBE is made available through the video adapter's BIOS, which installs interrupt vectors pointing at itself during system startup. Unfortunately, the older versions of VBE (those bundled with older video cards) provided only a real mode interface, which could not be used without a significant performance penalty from within protected mode operating systems, such as Windows 95 or Linux. This meant that the VBE standard was almost never used for writing video-drivers, and each video board vendor had to invent a proprietary protocol for communicating with their own boards. Despite this, many existing drivers for these video cards still thunk out to the real mode interrupt to initialize screen modes and gain direct access to a card's linear frame buffer, tasks which would otherwise require many hundreds of port writes which change from card to card. Most newer cards implement the more capable VBE 3.0 standard

• 1 Standards
  • 1.1 VESA BIOS Extensions (VBE core) 2.0 [November 1994]
  • 1.2 VESA BIOS Extensions (VBE core) 3.0 [September 1998]
  • 1.3 VBE/accelerator functions (VBE/AF) [August 1996]
  • 1.4 Supplemental specifications
    • 1.4.1 Power Management Extensions (PM)
    • 1.4.2 Flat Panel Interface Extensions (FP)
    • 1.4.3 Audio Interface Extensions (AI)
    • 1.4.4 OEM Extensions
    • 1.4.5 Display Data Channel (DDC)
    • 1.4.6 Serial Control Interface (SCI)
• 2 VBE mode numbers
  • 2.1 Modes defined by VESA
• 3 Other commonly available modes 
• 4 Linux video mode numbers
  
  The Linux kernel allows user configuration of VESA modes at boot time using the 'vga' kernel parameter. This parameter does not directly accept VESA video mode numbers; the Linux video mode number is simply the VESA number plus 512.
  The value can be passed to the kernel in the form 'vga=XXX', where XXX is the decimal value, or in form 'vga=0xHHH', where HHH is the hexadecimal value.
  As already stated, the modes above 1,280×1,024 are not covered by the standard, and every graphics card manufacturer uses its own codes. This means the modes, in red below, may not apply to your graphics card !

  	320 × 200	640 × 400	640 × 480	800 × 500	800 × 600	896 × 672	1,024 × 640	1,024 × 768	1,152 × 720	1,280 × 1,024	1,400 × 1,050	1,440 × 900	1,600 × 1,200	1,900 × 1,200
  16 colors					770			772		774
  256 colors		768	769	879	771	815	874	773	869	775	835	864	796	893
  15-bit (5:5:5)	781	801	784	880	787	816	875	790	870	793		865	797
  16-bit (5:6:5)	782	802	785	881	788	817	876	791	871	794	837	866	798
  24-bit (8:8:8)	783	803	786	882	789	818	877	792	872	795	838	867	799
  32-bit (8:8:8)1		804	809	883	814	819	878	824	873	829		868	834

  1: 32-bit is really (8:8:8:8), but the final 8-bit number is an "empty" alpha channel. It is otherwise equal to 24-bit color. Many GPUs use 32-bit color mode instead of 24-bit mode merely for faster video memory access through 32-bit memory alignmen
  • 4.1 Alternative Methodhwinfo is the hardware detection tool used in SuSE Linux and may be available in other GNU/Linux distributions. To use hwinfo to get the actual mode number that you need to pass as a parameter to the kernel:
    

    hwinfo --framebuffer
    

    The command should be run as root. Pick the number corresponding to the desired resolution. The modes reported by hwinfo are in hexadecimal. Use them with the '0x' prefix or convert them to decimal.
  • 4.2 Notes Modes 264-268 are text modes. 264 (0108h) is 80 columns × 60 rows (80×60), 265 (0109h) is 132×25, 266 (010Ah) is 132×43, 267 (010Bh) is 132×50 and 268 (010Ch) is 132×60.
• 5 Modes available in Parallels
• 6 References