BIOS and Firmware
1. What is UEFI?
UEFI stands for Unified Extensible Firmware Interface. UEFI is a replacement for legacy system BIOS and is flexible, fast, and efficient and has no driver size constraints. The UEFI pre-boot firmware architecture can be 32-bit, 64-bit, or IA64. There is no binary compatibility. Compatibility support module (CSM) is used to boot legacy operating systems and operate with legacy option ROMs.
Intel® Embedded Media and Graphics Driver (Intel® EMGD) for the Intel® Atom™ processor E6xx series and the Intel® System Controller Hub US15W chipset supports the Extensible Firmware Interface (EFI) graphics output protocol (GOP) driver, which gets merged into the UEFI system pre-boot firmware. The EFI GOP driver supports fast boot capability.
2. Is video BIOS (VBIOS) the same as the graphics output protocol (GOP) driver?
No. The GOP driver (also known as EFI video driver in some Intel EMGD documentation) is a replacement for legacy video BIOS and enables the use of UEFI pre-boot firmware without compatibility support module (CSM). The Intel EMGD GOP driver can either be fast boot (speed optimized and platform specific) or generic (platform agnostic for selective platforms).
Here is a quick comparison between GOP and video BIOS:
- GOP: No 64-Kbyte limit. 32-bit protected mode. No need for CSM. Speed optimized (fast boot).
- Video BIOS: 64-Kbyte limit (Intel® System Controller Hub US15W chipset) and 127-Kbyte limit (Intel Atom processor E6xx series). 16-bit execution. CSM is needed with UEFI system firmware. Performance inferior to GOP CSM. The VBIOS works with both 32- and 64-bit architectures.
3. Can VBIOS and the GOP driver coexist on a platform?
4. How is the VBIOS Option ROM linked to the display adapter in EFI pre-boot firmware?
The VBIOS Option ROM is linked with the PCI vendor-device ID of the VGA device (typically Bus 0, Device 2, Function 0). This information is embedded in the EFI pre-boot firmware at compile time or merged into the image on the host via the firmware vendor merging utility.
5. Which VBIOS is activated when I have an external graphics card such as Matrox* and internal graphics such as internal low-voltage differential signalling (LVDS)?
The answer depends upon the EFI pre-boot firmware setting, if available. If the "PCI as primary" option is available and enabled, then the VBIOS option ROM from the Matrox card is activated. If "PCI as primary" is not enabled, then the Intel EMGD VBIOS is activated. Note that there can be only one instance of VBIOS in the platform.
6. What are the VBIOS usage scenarios under Windows* XP?
Windows XP uses the VBIOS via INT 10h for displaying the splash screen and any messages until the graphics driver is loaded. Note that during the OS boot process the OS writes to the framebuffer directly, bypassing VBIOS for display purposes. After the graphics driver is loaded, the OS transfers control to VBIOS during full screen DOS mode and during “blue screen” to display the stack information.
7. Does Intel EMGD v1.18 for Windows Embedded* Compact 7 support the UEFI-based Intel® Boot Loader Development Kit (Intel® BLDK)?
Yes, it is supported on the Intel® Atom™ processor E6xx series-based platform.
8. Why did the CED generate 127K VBIOS instead of 64K VBIOS for the Intel Atom processor E6xx series?
Intel EMGD v1.16 (and onward) VBIOS supports 127K VBIOS for the Intel Atom E6xx processor-based platform and 64K VBIOS for the Intel System Controller Hub US15W chipset series. From Intel EMGD v1.16 onward, the 64K VBIOS for Intel Atom E6xx processor series is no longer available due to file size constraints as new features were added in the VBIOS that increased the file size to over 64K. If you require a 64K VBIOS, please consider using Intel EMGD v1.10 vBIOS package for Windows* XP and Linux* OS or Intel EMGD v1.14 VBIOS package for Windows 7, Windows Embedded Standard 7, and Windows Embedded Compact 7 OS.