uefi or bios boot query?

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uefi or bios boot query?

Postby 1885 » 2018-09-20 11:03

The question is?
Do we UEFI or BIOS boot.
I'd appreciate your input.

We currently have a lab with 25 towers running a ASUS ROG STRIX B360-H GAMING LGA1151 (300 Series) Motherboard.
This is a Computer Science / Cyber Security class at the High School level (USA)

The Debian guide:
https://wiki.debian.org/UEFI

"""
PC platform: BIOS, UEFI, CSM etc.
On the PC architectures (amd64 and i386), UEFI-based firmware is a relatively new replacement for the ancient BIOS (Basic Input/Output System) that has existed ever since the PC was first developed in the 1980s. The old BIOS systems have strict limitations due to their ancient design, running in 16-bit mode with access to only 1MB of memory, and limited access to other resources like disks. UEFI firmware is normally fully native and so should be able to access all the system memory and all the devices.

For the sake of backwards compatibility, most current PCs using UEFI also include a Compatibility Support Module (CSM), extra support code that will continue to boot in the old BIOS style. Over time, this support will most likely be phased out. Some systems were already being sold UEFI-only (i.e. with no CSM) in 2014.
"""
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Re: uefi or bios boot query?

Postby bw123 » 2018-09-20 11:28

I never tried to setup a project that large, but in general I find defaults to be easiest to deal with. I never change defaults unless there is a reason.

https://duckduckgo.com/html/?q=bios+or+uefi
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Re: uefi or bios boot query?

Postby Head_on_a_Stick » 2018-09-23 12:50

1885 wrote:The old BIOS systems have strict limitations due to their ancient design, running in 16-bit mode with access to only 1MB of memory, and limited access to other resources like disks. UEFI firmware is normally fully native and so should be able to access all the system memory and all the devices

More features always introduce the risk of adding more bugs and vulnerabilities so I would strongly disagree with the above statement in respect of "strict limitations" — the only advantage that UEFI offers is ease of multibooting (IMO).

The situation is slightly complicated though because non-UEFI systems may need an msdos ("MBR" style) partition table to work and GUID partition tables do offer several advantages so that may be another reason to prefer UEFI booting.

I think the Debian installer will default to UEFI if a GUID partition table is already present on the disk and the installer is booted in UEFI mode but it will install a non-UEFI system otherwise (ie, if there is an msdos partition table and/or the installer is booted in non-UEFI mode).
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Re: uefi or bios boot query?

Postby p.H » 2018-09-23 15:19

Head_on_a_Stick wrote:More features always introduce the risk of adding more bugs and vulnerabilities so I would strongly disagree with the above statement in respect of "strict limitations"

The "strict limitations" of BIOS systems are feature-wise, not security-wise.

Head_on_a_Stick wrote: the only advantage that UEFI offers is ease of multibooting

Is supposed to offer. But due to bugs in implementations and non compliance to standards, it can make multiboot a real nightmare.

Head_on_a_Stick wrote:The situation is slightly complicated though because non-UEFI systems may need an msdos ("MBR" style) partition table

Linux does not care.

Head_on_a_Stick wrote:I think the Debian installer will default to UEFI if a GUID partition table is already present on the disk and the installer is booted in UEFI mode but it will install a non-UEFI system otherwise (ie, if there is an msdos partition table and/or the installer is booted in non-UEFI mode).

The existing partition table does not matter. All that matters is whether the installer was booted in EFI or BIOS mode.
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Re: uefi or bios boot query?

Postby Head_on_a_Stick » 2018-09-23 15:35

p.H wrote:
Head_on_a_Stick wrote:More features always introduce the risk of adding more bugs and vulnerabilities so I would strongly disagree with the above statement in respect of "strict limitations"

The "strict limitations" of BIOS systems are feature-wise, not security-wise.

Which limitations would these be then? I am curious to know your opinion :)

p.H wrote:
Head_on_a_Stick wrote: the only advantage that UEFI offers is ease of multibooting

Is supposed to offer. But due to bugs in implementations and non compliance to standards, it can make multiboot a real nightmare.

Yes, I agree, lots of UEFI implementations seem to be crap.

p.H wrote:
Head_on_a_Stick wrote:The situation is slightly complicated though because non-UEFI systems may need an msdos ("MBR" style) partition table

Linux does not care.

The firmware does not care that Linux does not care :D

If the UEFI firmware is defective and will not boot a non-UEFI system from a GPT disk (in "Legacy" mode) then the operating system in use is not really relevant.

p.H wrote:
Head_on_a_Stick wrote:I think the Debian installer will default to UEFI if a GUID partition table is already present on the disk and the installer is booted in UEFI mode but it will install a non-UEFI system otherwise (ie, if there is an msdos partition table and/or the installer is booted in non-UEFI mode).

The existing partition table does not matter. All that matters is whether the installer was booted in EFI or BIOS mode.

Thanks for the clarification!
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Re: uefi or bios boot query?

Postby p.H » 2018-09-23 15:51

Head_on_a_Stick wrote:If the UEFI firmware is defective and will not boot a non-UEFI system from a GPT disk (in "Legacy" mode) then the operating system in use is not really relevant.

I have yet to see a BIOS or UEFI firmware in legacy mode which will not boot from a GPT disk. GPT has a protective MBR which satisfies most firmwares. Some require to set the boot flag on the protective GPT partition but this is not specific to GPT, they also require to set the boot flag on any partition in a standard MBR.
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Re: uefi or bios boot query?

Postby Head_on_a_Stick » 2018-09-23 16:01

p.H wrote:
Head_on_a_Stick wrote:If the UEFI firmware is defective and will not boot a non-UEFI system from a GPT disk (in "Legacy" mode) then the operating system in use is not really relevant.

I have yet to see a BIOS or UEFI firmware in legacy mode which will not boot from a GPT disk

I have participated in threads (more than one) in which the OP's motherboard would refuse to boot a Linux system installed in non-UEFI mode to a GPT disk with a BIOS boot partition. The systems would subsequently install & boot successfully if an msdos partition table was used instead.
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Re: uefi or bios boot query?

Postby milomak » 2018-09-23 21:44

Head_on_a_Stick wrote:
p.H wrote:
Head_on_a_Stick wrote:If the UEFI firmware is defective and will not boot a non-UEFI system from a GPT disk (in "Legacy" mode) then the operating system in use is not really relevant.

I have yet to see a BIOS or UEFI firmware in legacy mode which will not boot from a GPT disk

I have participated in threads (more than one) in which the OP's motherboard would refuse to boot a Linux system installed in non-UEFI mode to a GPT disk with a BIOS boot partition. The systems would subsequently install & boot successfully if an msdos partition table was used instead.

is that not why most solutions will have the creation of a fat32 partition to host efi?
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Re: uefi or bios boot query?

Postby 1885 » 2018-09-24 01:30

thanks for the posts! Educational!

we are going to experiment with uefi .

all the machines in our lab need bios tweaking which can be a bit difficult for beginners.

I might have a few advanced users tweak the bios to install with bios boot.

UEFI appears to be as controversial as systemd :)

I'm settin up a Debian system on a ASUS Ramgage IV with and I7 (Gift from a gamer)
The Rampage IV did not like UEFI
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