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Re: UEFI



On Wed, Jul 09, 2014 at 03:53:22PM +0200, Bzzzz wrote:
> BTW, sorry to hijack a bit this thread, but what could
> be the advantages to use UEFI (I just have Debian on my
> laptop and disabled it from ancient posts I read).

There was a good talk at this year's LinuxFest Northwest on this topic.
It doesn't seem to be videotaped, but the slides are at
http://2014.linuxfestnorthwest.org/sites/default/files/slides/uefi_presentation_0.odp
and there's some related reading at
https://www.happyassassin.net/2014/01/25/uefi-boot-how-does-that-actually-work-then/

There are a few major takeaways. Mostly they're of interest to OS
builders. Notably:

1. Traditional PC BIOS has no actual standards to define its behavior,
so there's a ton of variety between implementations. UEFI is
standardized in such a way as to make life easier for OS developers.

2. Traditional PC BIOS is basically still emulating an early 1980's era
IBM PC, and is incredibly limited in its capabilities. (Others have
pointed out the ability to boot from large disks as an example of this.
The PC partitioning scheme is another example.)

3. Secure boot. This is a bit weird, because nobody but Microsoft is
apparently interested in investing the resources into the infrastructure
to manage the PKI associated with this. Interestingly, Microsoft is
apparently happy to sign code for free operating systems, but most of us
don't bother and simply require that our users disable secure boot.

Another detail to note is that there's a common misconception that you
can disable UEFI. You can't. What you can do is disable secure boot, as
mentioned above, and enable a "compatibility mode", where the UEFI
firmware emulates a PC BIOS, but it is still UEFI.

noah


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