rEFInd sees Linux USB as "Legacy OS", can't boot.

[lepidotós]

USB is GPT formatted, fat32 (since that's what UNetbootin wanted), and contains a copy of openSUSE Leap 15.3. I haven't been able to get rEFInd to recognize it and when I try to select it anyway, it flashes a few red dialog boxes too quickly to see, then spits me back out to the screen above, locked up with the fans going on full blast.
Can't think of anything else to try.
Thanks if you help or even read this far.​

 

[rampancy]

Are you on a MacBook 1,x or MacBook 2,x? If so, you've likely ran afoul of the 32-bit EFI issue with Linux.

In short, *most* (but not all) Linux ISOs are formatted for a 64-bit EFI, which doesn't react well with the 32-bit implementation of EFI that Apple put on the Core Duo and pre-Santa Rosa Core 2 Duo MacBooks. (I haven't tested this with the MacBook Pro 1,x and 2,x, but I'm fairly sure the same applies to them too.)

The easy fix is to use one of Matt Gadient's modified ISOs, or use his isomacprog utility to modify the ISO you already have.

 

[lepidotós]

Yes, it's a 2,1 -- I thought I heard rEFInd could run 64-bit EFIs, but I guess not.​

 

[Snowlover]

Yes, it's a 2,1 -- I thought I heard rEFInd could run 64-bit EFIs, but I guess not.​

You could also try a 32 bit version of linux - mx Linux is still making a good one.

 

[rampancy]

Yes, it's a 2,1 -- I thought I heard rEFInd could run 64-bit EFIs, but I guess not.​

Well, rEFInd can run on 32-bit EFI Macs, it's just the Linux itself that's the issue. As Snowlover mentions, mx Linux can apparently run on 32-bit EFI computers. In my personal experience, the i386 versions of the Xubuntu and Lubuntu 18.04 can run on 32-bit EFI Macs, too.

 

[lepidotós]

the i386 versions of the Xubuntu and Lubuntu 18.04 can run on 32-bit EFI Macs, too.

Of course they can -- they're MBR/BIOS.​

The easy fix is to use one of Matt Gadient's modified ISOs, or use his isomacprog utility to modify the ISO you already have.

Gave it a shot, it didn't work. I can verify it has the 32-bit EFI, but it still shows up as Legacy OS.​

 

[joevt]

Does the USB have 32 bit EFI linux boot loader?

 

[lepidotós]

Yes. I just got done saying as much.​

 

[Wowfunhappy]

...I'm going to ask a dumb question.

The Clover Hackintosh bootloader is able to boot 64-bit EFI operating systems on machines that only support BIOS.

Macs with 32-bit EFI are able to support BIOS operating systems via Bootcamp.

Therefore, shouldn't you be able to go:

Mac w/ 32-bit EFI → Bootcamp → Clover → 64 Bit EFI OS.

Where that 64-Bit EFI OS could be OS X 10.8+

I'm obviously missing something or someone would have done this already.

 

[joevt]

...I'm going to ask a dumb question.

The Clover Hackintosh bootloader is able to boot 64-bit EFI operating systems on machines that only support BIOS.

Macs with 32-bit EFI are able to support BIOS operating systems via Bootcamp.

Therefore, shouldn't you be able to go:

Mac w/ 32-bit EFI → Bootcamp → Clover → 64 Bit EFI OS.

Where that 64-Bit EFI OS could be OS X 10.8+

I'm obviously missing something or someone would have done this already.

Isn't this how people boot El Capitan on MacPro2,1?
https://forums.macrumors.com/threads/2006-2007-mac-pro-1-1-2-1-and-os-x-el-capitan.1890435/
I don't think it uses a full EFI replacement from BIOS. I guess it uses a 32 bit EFI boot loader that provides 64 bit EFI Runtime Services interface to the OS.

 

[Project Alice]

Why not just run Linux in CSM? Pretty sure even modern ones still support legacy bios. Pretty much solves the 32bit EFI thing doesn’t it?

 

[NewbiePPC]

I not tried yet in a 32bit Efi MacBook but the following method works for me in my MP2,1 and in an intel atom tablet (bay trail) . I don't remember where I get the instructions so be kind with me since its copy paste from my personal notes txt and not give the credit to the author.

Why I do this?, because I prefer be sure that the SO that I going to be installed it's directly from the source and can update the Live USB when I need to the last revision or release. I know that are modified ISOS but I prefer to do it myself, although I don't know if there is some drivers preloaded in those ISOS to get for ex a MacBook full compatibility out of the box.

I believe that I installed from a DVD to get into CSM and as far as I know the only way to get into CSM in those machines is from a CD/DVD but I could be wrong.

Spoiler: 32bitEfi into a 64bitEfiIso

Create a (your linux distro) live USB to boot on the 32-bit EFI Mac. I used UNetbootin to create the live USB since it needs to be writable.

Download a current 64-bit Fedora ISO file (it contains the 32-bit EFI bootloader missing in your linux distro).

Delete or rename the (your distro) live USB /EFI directory, it will not support the 32-bit Mac.

Extract the entire /EFI directory from the Fedora ISO and copy it to the root of the Ubuntu live USB.

Also copy the (your distro) live USB's /boot/grub/loopback.cfg file to its /EFI/BOOT directory and rename it "grub.cfg" (delete or rename the existing grub.cfg first).
Edit the /EFI/BOOT/grub.cfg file like below, changing each "linux" and "initrd" label to "linuxefi" and "initrdefi":

For example, change this:

menuentry "Install Xubuntu" {
linux /casper/vmlinuz file=/cdrom/preseed/xubuntu.seed boot=casper only-ubiquity iso-scan/filename=${iso_path} quiet splash ---
initrd /casper/initrd

To this:

menuentry "Install Xubuntu" {
linuxefi /casper/vmlinuz file=/cdrom/preseed/xubuntu.seed boot=casper only-ubiquity iso-scan/filename=${iso_path} quiet splash ---
initrdefi /casper/initrd

 

[lepidotós]

@Project Alice
Can 64-bit Linux boot from BIOS? I suppose that would solve the issue.

 

[HexagonWin]

If you have a 2,1, I suggest you run coreboot.
Coreboot is a open source BIOS/UEFI replacement, and it supports your specific laptop!
With this, you can even run things like Opencore or x64 UEFI linux, UEFI windows, things like that. And you get much more security enhancements, faster boot.

 

[Project Alice]

@Project Alice
Can 64-bit Linux boot from BIOS? I suppose that would solve the issue.

It can on 64bit BIOS PCs. I don’t see why it wouldn’t on a Mac. I’m not sure if I have a Mac to test this on though.
I might have a MacBook 2,1 I could give it a shot on.