Are 64bit Dist all UEFI only ?
 

Are all 64bit distributions uefi only?
I want to dual boot a unit with a 32bit dist. on it, but when I run either Linux Mint Debian Edition 5 or PCLinuxOS both run fine from the live image but the installers only have UEFI options. LMDE5 actually does all the installation but on reboot only the old grub options for existing OS is shown, and I haven't found way to force it to boot from sda2 where it is installed which I suspect would fail anyway as it has a uefi partition but the unit does not have uefi enabled so presume will fail.

Modern Linux distros, like other operating systems, are now UEFI capable.

But in my opinion the actual value of UEFI is "not much." You can't program-in a specific UEFI-key and then tell your hardware to accept only that specific key. Without such a feature, it's not particularly valuable in terms of security.

I think if your machine is set for BIOS compatibility, & your disk is partitioned with an MBR, you will be able to install OK.

The short answer: No
Most 64bit distributions will boot in uefi or legacy mode. The determining factor is the system the iso is booting on. Most systems require secure boot disabled, fast boot disabled, legacy/csm enabled, and the drive type dos, not gpt.

Another option is to just have one 'bare metal' OS and put all the others in VMs. Eliminates all the dual/triple/etc. booting problems.

@rclark Yes good concept, but in this case I want to move to new OS while still being able to access the old for a while, I can see from the Live iso it boots and runs on the new one and lets me install but that install doesn't show up in grub after reboot, just the original.

@fatmac and @colorpurple21859-385635
Good to know, and the existing LMDE will be booting that way, but after doing the LMDE5 install it still only shows and runs the old LMDE from grub.

I may have dreamt this, but I thought there was a Linux utility disc that allowed you to boot it as a live ISO and from there you could select a partition to boot from .... this would let me confirm LMDE5 has run ... but maybe I dreamt that, as I had a bit of look and couldn't find anything.

I had a look in the grub.cfg in /boot/ on the old LMDE install ... but it is a bit daunting! There are so so many entries in there and a lot pointing to the original UUID for the old LMDE. I'm not sure where / how to add the new entry and UUID for the new LMDE5. I was hoping I could maybe use something like "grub-customiser" but the old LMDE no longer has updates so I can't install it (assuming it was available)

I don’t know what you’re talking about. VirtualBox sets its VMs up for BIOS boot by default, I always forget to change that, and I’ve never had a distro refuse to install for that reason.

supergrub2 will do this, once booted into the new system grub can be installed in legacy mode regardless of whether it booted in uefi or legacy

ta, actually all I had to do was let it boot in the old LMDE (only option showing in grub post the alleged LMDE5 install) and then from within that
sudo update-grub2
that detected the LMDE5 and added to the grub menu, rebooted and now can select either, sorted.
@dugan Someone else mentioned VM's ... not me ... I wanted base OS install to migrate from old 32bit to newer 64bit but be able to go back and forth eventually will shrink the 32bit further and ignore mostly. If I want to experiment I will use qemu, but this was about the base system.

I frankly agree with the notion that VM's – particularly VirtualBox, which is both full-featured and free – are far better than "dual booting." All modern CPUs have hardware support for virtualization which makes it very efficient. ("Containers" employ some of the same features.) You simply leave the host completely alone and do whatever you need to do in a window, and it actually works well.