Questions about triple boot (extlinux) strategy for Win7, Slackware64 and Linux Mint - audio production.
 

I am trying to work out a triple boot strategy for a laptop that will be used for audio production. The computer (weirdly) has to use legacy boot and MBR, as Win7 can't use the UEFI boot and GPT/EFI with the BIOS/UEFI.

Win7 is installed on 1/3 of the 2TB internal drive, and is being updated at this time. I was thinking of installing Slackware64 next, but rather than installing Lilo, I am planing on using extlinux as the boot loader. It looks like SlackDocs only has instructions for UEFI and/or GPT/EFI installs, so I took a gander here for a straight forward MBR install.

1) My first question is how extlinux is updated when changes have been made to the system a.k.a. lilo -v?
2) I haven't seen any mention of a recommended way to install extlinux in continuation of a Slackware64 install, but this video seems to be a sensible method except with the commands for the MBR of course. Any problems here that I should watch out for?
3) Installing Linux Mint would require that I not install a boot loader. How do you prevent GRUB being installed? (I can always try on the LM forum if no one knows.) Then I would just add an extlinux menu item for Linux Mint?

I'd go ahead and do this: this is what I'd do.
partition off a selection for both distros in one big chunk using windows partition manager.

if installing slack first. which it does not matter really which linux you install first. But I can go with Slack first. using cfdisk to partition off the big chunk of taken from windows into little slices for each distro, write, then,

install slack, install Lilo. set slack up post install, install grub using slack, or not because the other distro is next.

install next distro, it installs its grub over taking whatever boot loader is already there, picking up the other OS'es already installed on HDD. it now has command of the boot order and booting of same said OS'es using its grub.

that is the short order of it all. If windows is using MBR then install the linux ones MBR. nor would I have to figure out how to use extlinux, and maintain that everytime a kernel is updated. where grub is standard in Linux. Mint will just run it post hooks to update grub if it has a kernel update, and slack is a simple command line that can be put into a wapper for a shorter command to be ran in the cli, or a alias in bashrc if it is controlling the grub.

Thanks for the reply. As you state correctly, that will work for the laptop. However, the reason that I formulated this attempt at a strategy, is that I also have a tower computer which I would like to triple boot as well. This computer has five internal drives, three of these drives would be used for an OS per drive. Windows installs fine in UEFI mode, as does Slackware64 14.2 and other Linux distros work fine as well. All OS's work fine in both UEFI and legacy mode. However, the boot loaders do not. In legacy mode, both GRUB and Lilo have difficulty finding the target drives, and in UEFI mode, elilo always freezes with a kernel panic during the boot sequence. reFind can boot any system, but when elilo starts, there are a whole bunch of dots ....................... that appear, and nothing happens. That is why I thought it might be worth it to have a look at extlinux and use my laptop as a test bed.

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Here is the info on the tower computer motherboard:

I won't attempt to answer your question as I don't use extlinux, but in a similar situation, I simply pull up the EFI boot list (typically <Esc> or <F9/10>) and select the Win10 (started life as Win7) drive and let it boot as MBR.
The rest is handled by the default grub2 entry which does the Linuxes.

I tried for quite a while to make it all work, but I boot Win so rarely I didn't bother persisting.
KISS.

as I suppose it is due to spin up time for your HDD's depending on which one spins up first it gets the next letter. grub2 uses UUID's in MBR/legacy mode as well. I didn't notice you mentioning trying that yet.

I actually have tried that. UUID's help the issue, but it is still confusing as /dev/sda becomes /dev/sdb when switching between LM and Slackware. Of more concern is the elilo kernel panics. I am in the middle of a re-install, so time will tell if this remains a serious

Why not try talking one of your fastest hard drives and split it for your os’es then put your homes on the different hdds. That way it doesn’t get confused and should not hang up. You should still be able to have windows on its own hdd. The only drawback I can see is that Linux is only needs around 30GB so like a 120GB drive for your OS’es and bigger hdds for \home ‘s

or even use the extra space on your first hdd with the OS'es for data storage partition. that way your /home 's will still be separated and safe if you need to reinstall any one of the OS'es/

That sounds like an excellent idea. I have Win7 installed on the second physical drive in the drive bay of my tower computer, so I could easily install both Slackware64 14.2 and Linux Mint 18.3 on the first physical drive in the drive bay. Win7 is already installed in UEFI mode (needed to avoid the limitations of MBR partitioning). Now I just need one boot loader for a triple boot system. Too bad elilo doesn't fit the bill as I really hate configuring grub2.