Hi Flash,
Note: I have no experience with (U)EFI On Tue, Aug 30, 2011 at 3:35 PM, Flash K bootloader99@yahoo.com wrote:
Hi Graeme, I was checking out other alternatives to BIOS. I came across EFI , a new technology that seems to replace the BIOS in the near future. However I am still not clear as to where EFI fits in the booting process. They say that EFI cannot replace the BIOS but plans to do so in the near future.
(U)EFI cannot replace BIOS because most OS's still depend on BIOS to boot. BIOS provides a standard way for an OS to do some fundamental operations in real-mode (the mode the x86 CPU boots into) before the OS's switches to protected mode (and hence can no longer use BIOS). After the switch to protected mode, the OS's drivers interface directly to the hardware. Some of these fundamental operations include determining memory size and loading the core OS components from the hard drive
FAQs at http://www.uefi.org/about/ Intel also says that they are providing support for some motherboards. So is UEFI meant for use with the existing BIOS or with a custom developed BIOS from Uboot/Coreboot? Some information online also says that UEFI can be used as a payload for Coreboot. The entire thing is a little confusing. I am not able to understand where UEFI fits in with the BIOIS?
I suppose you could call (U)EFI a 'bootloader' of sorts. I theory, you could write an (U)EFI for a motherboard and have it do everything BIOS currently does (provided you knew all the ins-and-outs of the hardware components). I gather that (U)EFI is far more extensible than coreboot or U-Boot - But it is also a lot bigger (I have heard numbers up to 2MB - U-Boot is <256kB). I gather that the size is due to a single (U)EFI image being able to cater for multiple hardware configurations - Each U-Boot image is tailored to a very specific hardware configuration (or very limited set thereof)
As a coreboot payload, I think coreboot does some low-level init of the motherboard hardware (SDRAM for example) and then passes control onto (U)EFI
So until Linux and Windows support (U)EFI and stop supporting BIOS, (U)EFI is not going to replace BIOS
Regards,
Graeme