I just was playing around today with my 17 partitions of various FS on my 4 HDDs (2 readonly because already some sectors had gone bad) and 1 SSD, all MBR right now, and all this actually doesn't even matter, bacause just today I ran Ubuntu 18.04 installation from USB live flashdrive several times without any problems, just looking around, checking my ext4 partitions, checking what do i need to install Ubuntu alongside Windows, and what are the options.
About two hours ago, I booted through my UEFI BIOS, which settings i just don't change, except for choosing what to boot (which seems to change boot priority sometimes). I was running Ubuntu installation which is sitting on my flashdrive all day seemingly untouched, checking whatever (only having a look), then I booted in Windows, created some partitions on my SSD, then tried to reboot to Ubuntu... and got an issue described on the page below.
Can't install Ubuntu 18.10 on XPS 15 - EFI\BOOT\mmx64.efi not found
What I mean is I think I didn't do anything to cause this.
I tried to boot in not UEFI mode, it obviously failed. I thought why the hell such an important file was suddenly missing on my flashdrive, because it seemed fine. I booted Windows, checked the flashdrive. That \EFI\BOOT\mmx64.efi indeed wasn't there, I thought i'll reformat the flashdrive to FAT32 and do USB live media again. The file wasn't there. I tried to boot and it behaved just the same way, reproducing the same issue.
So, as stated in an answer to the question above, you probably solve this problem by renaming the file grubx64.efi to mmx64.efi. Ok, but why do I have to do that in the first place?
Last time I was using a PC was about a year ago, now I kind of didn't need anything new to do all I need, I was using all the familiar tools that I have used many times. Again I stumbled upon this fairly wierd situation, even though it solves quickly (thank God), I find myself not having any clue why.
So I guess my main question would be:
How on Earth a bootloader requires that mmx64.efi that isn't there?
As a programmer after a short retirement or a long vacation, I now have concern about in what situation a bootloader can use grubx64.efi and mmx64.efi in another. And for the sake of science, how do I make the flashdrive boot without changing the installation image? I would also appreciate references for further reading, as I want to become more fluent in 'such stuff'. Maybe even a book, if there is any. I seem to lack some deep understanding of underlying processes, so to speak.
