MP 1,1-5,1 Quick help: establish Linux boot option on SATA drive

[fhturner]

Hey Everyone—

This may be more suited to an OS forum, but since this is on a Mac Pro and I consider this forum my "home forum" I'm asking here for a quick bit of advice.

In order to use Ubuntu and an LSI SAS card to format a bunch of SAS drives w/ sg3_utils, I ran Unetbootin on one Mac Pro to create a Ubuntu installer, which I then used to install Ubuntu on a SATA HD in an internal bay. On that Mac Pro, if I wanted to boot into Linux, I could use the Option Boot Picker and choose "EFI" or similar. But I needed to relocate that SATA disk to another Mac Pro (both are 2009 flashed 5,1s), and now I do not see this Boot Picker option. In Terminal, diskutil shows that the disk and EFI & Linux partitions are recognized.

Can someone point me in the right direction for recognizing this partition to boot from again? NVRAM commands? Boot.plist entries? Something else? There's a lot of boot loader and dual-boot and other Linux-related topics upon Googling, but I don't see a quick and easy way to re-establish the same functionality I had. And since I'm really just using Linux for this one task, I don't want to go through a bunch of hoops and changes to get it back.

Thanks!
Fred

 

[flaubert]

Are you running a PC graphics card like the RX580 or similar? If so, they don't start functioning until the operating system loads drivers, and thus there is no longer an Option-Boot possible.

 

[fhturner]

Are you running a PC graphics card like the RX580 or similar? If so, they don't start functioning until the operating system loads drivers, and thus there is no longer an Option-Boot possible.

No, not at the present time. I'm using an HD 5770. I don't have any trouble showing the Boot Picker, but the "EFI Disk" option is not showing up. Since I had only added one utility package to the previous installation, I wound up just generating a new installer USB Drive, then installing a 2nd copy alongside the first on a new partition. Added back the sg3_utils and could go about formatting disks again.

Still, if anyone has a quick way to make Linux EFI boot options show back up on the Mac Boot Picker screen, I'd be happy to know that for future reference.

Thx!

 

[Macschrauber]

If you use an Apple 5770 with bootscreen than this is a little helper

rEFIt - An EFI Boot Menu and Toolkit

refit.sourceforge.net

 

[tomsmods]

Can someone point me in the right direction for recognizing this partition to boot from again? NVRAM commands? Boot.plist entries?

First google result was something like https://medium.com/@mmiglier/ubuntu...ith-pure-efi-boot-mac-compatible-469ad33645c9

I was using a variation of that guide when I had a Linux Mint 18 EFI install. The article goes in depth for building grub sources, mounting HFS+ partitions etc, but I didn't have to do most of it after finding this forum post: https://askubuntu.com/questions/831161/dual-booting-os-x-or-macos-with-linux-without-refind

The magic is getting your install's grub EFI files from /boot to the EFI partition. Typically this just means copying those files, but since your linux install containing the /boot folder may be on an ext4 or other partition the Mac can't natively read, you may need to boot from a Linux Boot CD/USB and copy from there.

I recall after a fresh Linux install the mac would always boot to Linux as the installer had set the boot parameters, but once changed on the mac I could not go back to Linux without the Linux Boot CD. When I copied the EFI boot files it was then visible with option-boot picker.


Your comment that it worked before you swapped drives means those (EFI) files may have been copied to another drive/partition, and it was never booting from the Linux drive itself. I had something similar happen where Windows was not longer bootable once I removed my Mac OS drive. The windows installer seems notorious for putting its bootloader EFI files on another EFI partition (often the Mac's EFI partition), which is why it works best to remove all other drives when installing Windows.

I've since changed to a CSM (BIOS/MBR) Linux install to so that it can be selected from a Windows Boot picker that is visible from the startup disk preference pane. Also, the EFI boot only worked from option-boot startup. Using startup disk preference to select the disk would get stuck at flashing cursor. EFI Linux "seemed" faster and supported larger disks.

On similar workstation PC's there are BIOS settings for selecting EFI, BIOS/CSM, and also "option-ROM" type for correct booting. These settings are not available on the Mac so I find it cleaner to keep Mac installs as EFI and non-Mac installs as CSM.

Others use rEFInd to not deal with the limitations of the native EFI bootloader.