"Do UEFI specifications completely replace the BIOS?"
Do UEFI specifications completely replace the BIOS? (From uefi.org/faq)
The UEFI specifications define an interface and the BIOS refers to a specific implementation of the firmware that initializes the platform and loads an OS setup. UEFI specifications define an interface in which the implementation of UEFI performs the equivalent of the BIOS, by initiating the platform and loading the operating system.
This is what I found in the official uefi.org website but I'm really not able to understand the answer.
On the net I found:
UEFI does not completely replace the BIOS. UEFI uses a separate interface for boot services and runtime services, but does not specify how the Power-On Self Test (POST) and Setup are implemented. Some platform firmware must still perform these crucial functions, however. Because UEFI is an interface (as its name suggests), it may be implemented "on top" of a traditional BIOS (or, for that matter, a non-BIOS system).
And I didn't find an example of platform that do not perform a POST (or at least I don't know how to search for it)
- There are system that exclusively have UEFI?
- Is it sufficient the UEFI high level hardware check?
- If UEFI is on top of BIOS where is the exact point when one ends and the other starts? How?
UPDATE:
Read the always excellent ArchLinux documentation
When a motherboard, hardisk, SSD etc powers up it runs its firmware. For PC style motherboards there are three common firmwares:
- BIOS.
- UEFI.
- CoreBoot.
Each of these is standalone. Neither runs on top of anything else.
So to answer:
There are system that exclusively have UEFI?
Yes, almost any modern system
If UEFI is on top of BIOS where is the exact point when one ends and the other starts? How?
It is not on top off. The motherboard either starts on or do other. There is no handoff.
I suspect that these two questions partially originate to articles which are plainly wrong. E.g. many post say "UEFI BIOS". Which is plain wrong.
Another potential point of confusing is that many UEFI implementations ship with a compatability module (CMS) which emulates the same functionality as BIOS firmware used to offer. But it still is a different product.
That leaves one question which I do not understand:
Is it sufficient the UEFI high level hardware check?