So I now own hardware that is actually from this decade.......

[claydoh]

.....and have a lame noob question.

Is there any reason (compelling or not), in a linux only system, to use efi over legacy bios? Other than secure boot, if and when such a security measure is warranted in Linux.

I can't seem to find much opinion on this.

[Qqmike]

Is there any reason (compelling or not), in a linux only system, to use efi over legacy bios?

I can't think of any. You can use BIOS with GRUB2 to dual boot. What about the partition table, will it be legacy MBR (which is OK) or the newer GPT? AFAIK, BIOS will boot GPT with GRUB2 (I did it when GRUB2 was new), with an adjustment (needing a BIOS Boot Partition, I think). Of course, some (including SteveRiley) would encourage you to convert to the new system just because it's going to be dominant in the market now. And, frankly, for Linux only, it is not more complicated than BIOS+MBR+GRUB2 (which might even be a bit more complicated!). The GPT (instead of MBR) is needed because the drives are getting bigger and MBR has that 2 TB limit on its addressable disk size. If you have the newer UEFI booting, you have the option of using the boot manager rEFInd to help out (it is only for UEFI), and it can go alongside GRUB2-EFI with NO problem, or replace GRUB2-EFI (with some adjustments) (my rEFInd is in addition to GRUB2-EFI, and it sure helps out when there's a booting problem! rEFInd seems to be able to boot anything).

Other than secure boot,

Most writers I read advise to disable Secure Boot, including SteveRiley, and I've disabled mine. Even with Windows, it's a question whether you need it or not.

[Qqmike]

Rod Smith is the expert on EFI/UEFI. He's also the author of the UEFI boot manager rEFInd and of GPT fdisk (gdisk). He's a Linux guy but he does Windows also. His page on Quick UEFI Installation contains some tidbits here and there that bear on your question indirectly:

http://www.rodsbooks.com/linux-uefi/

[claydoh]

Thanks!

I may use it if I replace the drive in this thing, but if I have to do a lot of outside prep that isn't normally handled by the installer, I probably won't use it.
Yes, lazy.

[oshunluvr]

One thing: GPT vs. MBR tables. I advocate GPT formatting but GRUB needs a bit of prep. Hold on - I'll find my post on this...

...Ahh, here it is.

[claydoh]

Man, you said the P word, lol!

[Qqmike]

First post this morning, feeling in a mood to type!

oshunluvr: GPT vs. MBR tables. I advocate GPT formatting but GRUB needs a bit of prep.

Yes, that's what I'm referring to (above) -- you need room for Stage 2 of GRUB, which calls for the Bios Boot Partition. Nice work oshunluvr, but not for me anymore! Too much prep! ;-)

After using UEFI now since about February 2015, I'd had trouble going back to straight GRUB on MBR or even on GPT. GRUB2 for EFI is simpler, cleaner (though technically more complex under the hood -- but, you don't have to get into any complexity, just let it do its work; and if there's a problem? just re-install GRUB with one command: sudo grub-install! or fall back on rEFInd).

claydoh: I may use it if I replace the drive in this thing, but if I have to do a lot of outside prep that isn't normally handled by the installer, I probably won't use it.
Yes, lazy.

Prep ... thinking through it now ...

First, definitely use a GPT. In GParted (or, I think the KDE Partition Editor), it is easy to format your disk as GPT: Device > Create Partition Table --> gpt => Done.
Then, while you are in that partition editor, make your EFI System Partition (called the ESP):

sda1, the first partition (or anywhere, if sda1 is already occupied, maybe sda2, doesn't matter)
FAT 32
200-512 MB (I go with 512 MB but 200 MB would be more than adequate if just booting a dozen or so Linux OSs using it.)
Finally, set the boot flag on that partition: Partition > Manage Flags --> boot.
It doesn't mean sda1 is bootable in this case; in UEFI, using GParted, setting the boot flag marks that partition as the special ESP partition to be used by the UEFI firmware of your computer and by the new GRUB2-EFI.
That's all.

In GParted, Create the GPT, create the ESP, exit.
Then run the Kubuntu installer DVD in UEFI mode, and choose Manual Installation type.

Now here's a thing. Let's say you just formatted the drive as GPT in GParted. But you didn't make your own ESP. Would the Kubuntu installer, running on "automatic," sort it out and make a UEFI setup for you, including the ESP, root, home, swap? I think it should, but I never tried the automatic option; always used the Manual option on the Installation Type screen; and there, the Kubuntu partitioner DID see the ESP I had already set up and it used that ESP, as did the GRUB2-EFI scripts during installation--automatically..


One thing you must do, though, always, with UEFI, is to run your Kubuntu installer in UEFI mode! Then many things ARE automatic (GRUB2 installer scripts, the UEFI efibootmgr installer scripts, your Kubuntu installer is then UEFI aware, etc.). I just posted this quote from one of my how-to's on runing in UEFI mode:

https://www.kubuntuforums.net/showth...l=1#post379756

It's easy: you re-boot the computer, enter your UEFI firmware setup (which we used to call BIOS setup), look for the list of bootable devices, you will see your Kubuntu installer DVD/USB, and you may see the DVD/USB listed twice -- once as a normal DVD/USB and once tagged as a UEFI DVD/USB, like "UEFI TSSP Corp DVD..." or "UEFI KingstonDataTraveler16GB ..." Pick the UEFI choice to boot and off you go! After you make your UEFI selection, your UEFI firmware should just start the booting of that DVD or USB using UEFI mode.


Behind all the possible technicalities, I always keep one simplifying picture in mind:

You got your root, home, swap, as usual. As for booting the OSs, you got your ESP (it is usually sda1, but can be anywhere, FAT32, 200-512 MB, set as "boot" or as type EF00). Inside that ESP are the boot loader files for ALL your OSs on that computer. Windows is here: /EFI/Windows. K(U)buntu is here: /EFI/ubuntu. Suse: /EFI/suse. Debian: /EFI/debian. If you look inside any of those subdirectories, you will see--for that OS--the handful (maybe 1-4 files) of GRUB boot files and other UEFI utilities/tools. Period. That's it. When you boot up your computer, the UEFI firmware of the computer does its thing -- looking inside the ESP subdirectory for your OS to see what to do -- and boots up your OS for you.

Of course, just like with the older GRUB setups, MBR, GRUB2+GPT (oshunluvr's choice), etc., if you want to start doing fancy things, setting up wild multi-boots and so on, there's no end of fun and games. But for basic setups (including basic multi-booting), you probably won't even know or care that the UEFI machine I outlined above is even doing its thing for you.

Admittedly, dual-booting with Windows can be a trip, or it can be made simpler, too. Most of the real messy issues I see with UEFI involve setting up special multi-boots with Windows.