Snoope at Boot time.
I discovered this during 32 bit ERA and I gradually weaned myself off through, Puppy Linux, Peppermint, SuSe, Redhat, PCLinuxOS and finally Gnome of Debian.
I was a Window's guy to begin with and used Partition Magic to divide the my analogue PC Hard Disk to 15 Partitions, the maximum those days.
I had huge books on Linux and I used to Edit the Boot Loader manually to suit my preferences.
There are things called Primary partitions and extended partitions.
There is a limit for Orimary Partitions to a maximum of 4. That means I can have only 3 Linux Distributions and First one was Reserved for Microsoft by default.
1. Boot Windows.
2. Install Partition Magic
3. Make the 4th partition Extended to accommodate the Logical partitions with a symbolic link, so I can have up to 15 partition in total.
In other words, I could have had 15 Linux Distribution in one hard disk.
But with having /boot, /root, /home, /var and /tmp according to Debian Protocol, I would have 4 additional Linux on top of Microsoft Windows.
If I have 2 hard disks:
1 primary and 1 Extended
1 primary and 1 Expended
Then, I can have theoretically 30 distributions distributed over 2 hard disks.
But there is a caveat here.
Boot record has to be on the first drive and the second drive has to be connected at all times. I tried having the Boot Record on the second drive.
I still have the PC and two 1 terabyte SATA disks in Ceylon. I did not put them in my travelling bag fearing overweight but put the Laptop in instead.
Well, I could buy some SATA disks in Australia.
I used the First Hard Disk for my work including Microsoft Windows and the second hard disk was used for testing Linux Distribution.
This the time, I decided to test 100 Linux Distribution but it went up well beyond 200.
I did not like Live Sessions.
I wanted them installed.
MB
This was the Master Boot Record ERA with above restrictions.
Since, Partition Magic went commercial I quickly moved and discovered GPT.
I was into Gnome Partition Tool and GPT Partiion Table very early. That saved me enough headaches, booting multiple Linux Distributions in one PC.
I had network of 16 IBM computers all discarded from America and Canada but in trim working conditions.
They were all 32 bit computers and 32 bit computers were gradually phased out.
I discarded the lot, except one and quickly moved to 64 bit compuers.
Coming back to AI and UEFI,
EFI stands for Extensible Firmware Interface.
U stands for Unified System.
All these are determined by Intel and big companies that manufacture hardware.
Linux guys were skeptical about EFI but slowly adopted it, since this firmware interface extended the capabilty of Linux without a hitch.
In other words expanded its scope.
Before the half and hour discussion with AI I had a narrow view about evolving technology.
If my system works, I do not bother about investigsting new frontiers.
Then, comes a crazy Idea.
I would boot 10 Linux Distributions in my NUC and Old Laptop.
I have 11 in the Laptop with 500GB and 10 distributions in my NUC (But 2 or 3 are multiple instances of Debian).
So I had to stopp at 8 and not 10.
Getting there I had lot of problems.
Partly due to poor vision and partly due to lack of sleep.
Problems were
FAT partition
EFI
Type of File systems, basically EXT4 and Btrfs.
Linux Distributions have there own approch to evolving technology but very little dialogue with the User.
Some of them begin to think you got to take what we give you, just like hegemonic Microsoft attitude.
While doing this multiple installation I got a bright idea.
I would boot Linux Distribution from a EXT4 partition.
I achieved it.
MANJARO ❤️ is now booting from an EXT4 partition placed FIRST
But after bit of fiddling.
Outcome
Three types of Linux Distributions.
1. Linux Distribution that bumsuck to Microsoft strategy.
UBUNTU, Bodhi, Emmabantus and almost all the Ubuntu derivatives.
I hate these distributions.
I DO NOT use them.
2. Linux Distributions that use EFI and GRUB.
DEBIAN was the first Linux Distribution to adopt EFI but I would boot Debiaj without Windows in the system.
MX Linux and MX derivatives.
3. Linux Distribution indifferent to bith FAT and EFI.
MANJARO
ARCH Linux Gamer is SUPERB.
BlueStar star is the most beautiful KDE Desktop.
Probably Linux MINT but I did not try it.
I hate Linux MINT again based on UBUNTU.
It is SLOWLY moving to Debian.
I tried it "Only Once" and it got the GRUB configuration WRONG.
Strangely, MANJARO comes top of the list.
BIG Linux second.
CachyOS nowhere (regarding my old lsptop). It can live with Debian but never with another ARCH especially Manjaro and I ditched CachyOS to the versatile BIG Linux with a Beautiful Plymouth.
BIG Linux solved my problem.
CachyOS thinks it is the only Linux Distribution that landed on this Planet when booting on old Laptops.
I won't try it any more.
I'll settle with MANJARO, BIG Linux and MX Linux.
Spe❤️cial Mention
ELive Linux.
But the kernel is pretty old.
But comendable by having Blender.
I have a copy on my Laotop.
AI Advice
1. Do the installation in daytime after a good night sleep.
2. Used multiple instances of EFI
One for Debian
One for Testing distributions.
Fully agreed but won't try this method since things are working OK in both NUC and Laptop with each having 10 to 11 distributions
3. Try rEFind init
This I used in 2018 and 2020 Coronavirus pandemic when I tried TrueOS and BSD.
4. Write down the Partition Table in a Note Book.
I have been doing that all my life.
Since with age becoming a handicap (short term memory) It is (writing down) is my default approach.
5. Ask AI before plunging into big ideas.
I am very happy with AI's technical advice, I would consult it in advance in future adventures.
Please NOTE.
All these comments are for my Old Laptop.
It was in the attic to begin with and I revived it.
It looks brand new now.
REBORN OS and Peppermint Linux could not configure the Laptop's Keyboard.
Peppermint , PCLinux and Modicia are all in my NUC and they working fine.
Only distribution not there is ELive and I am going to ERASE one of the Debian instances and install ELve also.
This attempt was failed by ELive itself to extract few dollars from me.
I still have 300 US dollars pocket money in my wallet. I am going to use it to by a Photonicat2 portable Mini PC with Debian Installed.