BootIt Makedisk - choosing Build Options?

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timg11
Posts: 229
Joined: Sun Oct 02, 2011 4:31 pm

BootIt Makedisk - choosing Build Options?

Post by timg11 »

What are the factors to consider when choosing whether to use BIOS or UEFI?
If the computer has a UEFI BIOS, is it required to build for UEFI (if special UEFI features such as secure boot are not being used?)

I want to create a triple-boot system, with BootIt providing a menu choice between Windows, Ubuntu, and IFL.
Would BIOS or UEFI provide the easiest path to success?
Given I have less experience with UEFI, I'm thinking BIOS would be better unless it simply won't work.
CyberSimian
Posts: 127
Joined: Wed Aug 10, 2016 12:13 pm

Re: BootIt Makedisk - choosing Build Options?

Post by CyberSimian »

timg11 wrote:
> What are the factors to consider when choosing whether to use BIOS or UEFI?

I have two systems that have a BIOS that supports UEFI (one tower system, one laptop), but I use BIBM on both of them. To be able to do this, the BIOS must have support for "legacy booting" (it might be called something else on your system). I suspect that eventually manufacturers will withdraw support for legacy-booting in order to force people to move to UEFI-booting in the belief that UEFI is superior, so you need to check what your system supports now, or what the system that you are thinking of buying supports.

For me, the important points are:

(1) BIBM can boot ONLY from a disk that has an MBR partition table, but BIBM can see and partition disks that have GPT partition tables (so you can have a system consisting of a mixture of MBR and GPT disks; my laptop is like this).

(2) BIU (==UEFI) can boot ONLY from a disk that has a GPT, but BIU can see and partition disks that have MBR partition tables (so you can have a system consisting of a mixture of GPT and MBR disks).

(3) An MBR disk has a maximum usable size of 2TB. If you install BIBM on a larger disk, the space in excess of 2TB will be unusable (and hence wasted).

(4) If you use unlimited primaries in BIBM, you can truly hide MBR partitions from the OS that is booted (because the OS sees that space as unused). You cannot hide GPT disks which are in the system.

(5) BIU cannot truly hide partitions -- its sets a bit flag somewhere in the boot record, and it is up to the operating system to decide whether to honour that flag, or to make the hidden partitions accessible to the booted operating system.

(6) It is possible to have a system that can boot one OS in MBR mode, and another OS in UEFI mode. My laptop is like this. The catches are:

(a) The operating systems must reside on separate disks (so not possible in a laptop that has only one disk).

(b) You have to use the "Boot Menu" that is part of your BIOS to select which disk to boot. If you select the MBR disk, it will boot in MBR mode; if you select the GPT disk, it will boot in UEFI mode. This is how I operate my laptop, but I rarely boot in UEFI mode (I keep this ability available because the BIOS-update utility provided by the laptop manufacturer operates only in UEFI mode).

(7) There may be a problem booting from an NVMe M.2 SSD in MBR mode. My laptop has one of these, but I use that only when I boot in UEFI mode. When booting in MBR mode, I use the larger SSD that has a SATA connection (so someone else will need to comment on whether NVMe disks cause a problem for MBR booting).

-- from CyberSimian in the UK
timg11
Posts: 229
Joined: Sun Oct 02, 2011 4:31 pm

Re: BootIt Makedisk - choosing Build Options?

Post by timg11 »

Thank you for the very helpful response! The system has a single 256 GiB M.2 SSD with a GPT partition table.

Based on your points (1) and (6)(a), I will proceed with BIU
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