How to make EFI Macbook Air boot Linux from external drive?

[spiderman]

Okay just to do a recap on what actually happened, I plugged in a 256 GB solid state disc into my Apple MacBook Air Linux install disc, and I installed system onto the 256 GB external disc attached to the Macbook with the internal 128GB Linux drive. After that, the MacBook Air would not boot to the original disc / operating system on the internal drive without the external drive plugged in.

I went through the process to fix the boot track on the MacBook Air. So now that MacBook Air boots to its own original Linux drive, however the 256 GB drive with Linux on it will not boot. So I took my Active Boot Disc drive cloning software & I took that program and cloned a working EFI boot drive. I used that to install an EFI boot partition on the hard drive. It's about 512 MB. (I duplicated the EFI drive on the 128 GB EFI track to the 256 because the original install put an empty EFI disc there.) (see image for GRUB Error)

After looking at the GRUB error, My question is, What is my next step to get this drive to boot on it’s own? I am willing to edit the GRUB config file, but I think it would be possible to boot the Linux partition using another boot loader besides GRUB and then run APT to update/install GRUB again to fix the problem. What are your tho'ts?

[bigpup]

What specific Puppy Linux version you trying to use?

We can tell you how to get Puppy Linux installed on the external drive and get it to boot.

[retiredt00]

Dear spiderman
maybe easier to have suggestions if we know a bit more
1) which macbook (x86 or Apple silicon)
2) is it still running macos too
3) which other linux was loaded in the 128GB internal partition
4) how where the Grub 2.12 boot loader was installed
5) which puppylinux in the external disk
6) How puppylinux installed and what is the bootloader

My guess would be that the original grub configuration was not edited properly to point to the external disk, and likey the boot loader on the external does not know about the internal, but without knowing exactly how and what this system is trying to boot is hard to tell

You may want to provide blkid output when all the disks are connected and and the grub.cfg file from the internal and external disk