Mixed BIOS types?

[Jordan3]

Is there a way to have 2 op systems on a computer, one under UEFI and the other Legacy Mode?
I'd like to install MX under UEFI, but keep the existing Windows system bootable, which is Legacy.

[Pierre]

ideally - you shouldn't do that - as it can cause some Boot Issues.

which version of Windows ? the later version(s) are already in UEFI mode,
& you can thus install MX in the same manner.

[Jordan3]

It's Win7, under Legacy mode.
I don't want to risk boot issues, but I want to use UEFI for MX.
To keep some access to Windows, would this work reliably? :
- Change the BIOS to UEFI, and install MX on a different, empty hard drive in the same computer.
- If & when I want to access Win7, temporarily change the BIOS setting back to Legacy.

Would I then be able to see files from the Win system, from MX?

[Pierre]

then you should also be able to install the MX system in Legacy Mode - as well.
- I've done that a few times, now & it worked, just fine.

[fehlix]

Is there a way to have 2 op systems on a computer, one under UEFI and the other Legacy Mode?
I'd like to install MX under UEFI, but keep the existing Windows system bootable, which is Legacy.

Yes, it is possible. I wouldn't recommend a mixed BIOS/UEFI mode for new user, but if you want to "play" with it you can do it.
Some UEFI-firmware do make it easy to select to boot in BIOS or in UEFI mode, some other do make it a bit more complicated to switch.
The easiest - to check it out - would be if you have a 2nd HDD/SSD and reformat it within the GPT partition scheme,
or you use this 2nd disk and install MX-Linux in automode on that disk. (EDIT: when booted MX Live in UEFI mode)
If you have only one disk, which is already partitioned within MBR (MSDOS) partition layout, it might work also,
but I haven't tried this out it yet.
If no automode in MX Installer (when booted MX Linux Live in UEFI mode) is used you need to manually create required partition like ESP (EFI System Partition in FAT32 with esp/boot flag) and at least a rootMX-partition (ext4) for MX linux.
After you have done this you can boot in BIOS mode into WinOS and in UEFI mode to MX Linux.
You might need to create a further "fallback" EFI-BOOT directory on the ESP ( mkdir EFI/BOOT ) and
copy MX efi-boot loader from EFI/MX18.2/grubx64.efi to EFI/BOOT/BOOTx64.efi.
The last step is only needed for some UEFI firmware to boot from a new partition/disk, if the internal EFI-bootmenu was recreated.
And further if you go one step further you can install GRUB boot loader for BIOS(legacy) booting into MX Linux.
E.g. use MX Boot Repair booted MX Live in BIOS mode and install GRUB in MBR of the 2nd disk.
For this to work it advisable to have a small 1-2 MB unformated partition created (e.g just after the ESP-partition) and to be marked with a bios_boot-flag ( mark in Gparted).
So you see lot's of ways and flexibility.
HTH

[Jordan3]

I'm not ready for advanced techniques, just thought UEFI could be worth having MX run under, if it was easy to do.
In my case, it might be better to keep it all Legacy after all.
What's the worst thing about doing that?
Thanks for comprehensive advices, by the way.

[Sgthawker]

I installed to separate hard drives with the other disconnected so each had it's own boot sector. Set linux as primary in BIOS and used update grub so grub can see the win install and used grub to select which OS to boot at each poweron. I think this isolation prevents hiccups caused by win updates.