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#1 2023-10-22 21:57:59

WDstudios
Member
Registered: 2023-10-22
Posts: 17  

Multiboot help

I'd rank Devuan as a "medium" on the scale of user-friendliness, in the sense that I can install it in a virtual machine without issue, but if I try to install it on bare metal alongside a WinXP or Win7 partition, there's about a 50% chance that I'll end up with a system that can only boot into Devuan, and a 50% chance that I'll end up with one that can't boot into any OS at all, because I didn't understand what most of the options were during setup.

The good news is that I was able to get my laptop's Win7 partition back by installing MX-23 into the space that Devuan used to inhabit. Thank God for YUMI multiboot USB sticks.

Anyway, while fiddling around with hard drive partitions, I noticed a 100MB "system reserved" partition, which means that I forgot to set the partition table from GPT to MBR when I wiped the hard drive and installed Win7.

I'd still like a Win7/Devuan dual-boot system, and I'd prefer to do it without wiping the whole hard drive again just to set it from GPT to MBR. Any help would be appreciated.

Last edited by WDstudios (2023-10-22 22:04:22)

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#2 2023-10-22 23:19:50

fsmithred
Administrator
Registered: 2016-11-25
Posts: 2,441  

Re: Multiboot help

In newer versions of grub, os-prober is disabled by default. Edit /etc/default/grub to enable (un-disable) os-prober. Like this:

# If your computer has multiple operating systems installed, then you
# probably want to run os-prober. However, if your computer is a host
# for guest OSes installed via LVM or raw disk devices, running
# os-prober can cause damage to those guest OSes as it mounts
# filesystems to look for things.
GRUB_DISABLE_OS_PROBER=false

And then run update-grub

Note: if you booted into devuan from mx's grub, you'll need to run 'grub-install' from devuan.

If you're using gpt with bios boot instead of uefi, you'll also need a special partition for that. i think it's called bios_grub in gparted and ef02 in gdisk. Needs to be 1mb and have no filesystem on it.

Time for dinner. Yell if this doesn't make sense.

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#3 2023-10-23 14:08:30

WDstudios
Member
Registered: 2023-10-22
Posts: 17  

Re: Multiboot help

fsmithred wrote:

Edit /etc/default/grub to enable (un-disable) os-prober.

Uh, how?

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#4 2023-10-23 17:12:03

rolfie
Member
Registered: 2017-11-25
Posts: 1,088  

Re: Multiboot help

WDstudios wrote:
fsmithred wrote:

Edit /etc/default/grub to enable (un-disable) os-prober.

Uh, how?

You know how to call up a console? And how to gain superuser rights? Here is a rough guideline:

$ su -
# cd /etc/default
# nano grub
# update-grub

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#5 2023-10-23 17:36:13

WDstudios
Member
Registered: 2023-10-22
Posts: 17  

Re: Multiboot help

So it's not an option during installation? I have to let Devuan lock me out of Win7 and then hope I can fix it later?

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#6 2023-10-23 18:01:52

rolfie
Member
Registered: 2017-11-25
Posts: 1,088  

Re: Multiboot help

Nope, you have to enable os-prober past the first boot of the installed Devuan. And there is no need to hope, it will work as a charm when enabled. It simply works when enabled.

BTW to set the mind right: Devuan is a Debian w/o systemd. You may find a list of banned packages on the Devuan webpage. Where appropriate or required, the Devuan team has developed replacements. All the rest is Debian.

Edith: forgot to mention, the decision to disable os-prober per default was a Debian decision.

Last edited by rolfie (2023-10-23 19:00:19)

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#7 2023-10-23 18:18:40

rolfie
Member
Registered: 2017-11-25
Posts: 1,088  

Re: Multiboot help

Some comments to a dual boot with Windows.

First: Windows should be installed first and sets the boundary conditions for the partitioning scheme of the system disk. Legacy install means MBR partitioning, UEFI install means GPT partitioning. Valid for Win7 and newer. My advise for going on to use XP: copy it into a VM.

Second: Linux systems don't care about MBR or GPT, legacy and efi, installation is possible in any combination. But side conditions do apply:
- for a legacy install on a GPT disk you will need a bios-grub partition with no file system on it.
- an uefi installation requires an esp. Size somewhere from 128M to 512M if you are generous, FAT32 as file system is mandatory, best is if its the first partition on the disk, esp flag set.

Some side effect of the os-prober: it can't find other encrypted Linux installations. Manual work is required to add such a system into grub.

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#8 2023-10-24 03:12:44

WDstudios
Member
Registered: 2023-10-22
Posts: 17  

Re: Multiboot help

rolfie wrote:

an uefi installation requires an esp.

ESP? Extrasensory perception?

rolfie wrote:

Size somewhere from 128M to 512M if you are generous, FAT32 as file system is mandatory

Well, that explains why there was a 512 mb FAT32 partition on the drive after I installed Mint...

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#9 2023-10-24 04:40:35

steve_v
Member
Registered: 2018-01-11
Posts: 348  

Re: Multiboot help

WDstudios wrote:

I have to let Devuan lock me out of Win7 and then hope I can fix it later?

Could be much worse, the Windows installer will simply overwrite any other bootloader without prompting, and you'll need to fix it manually from a live distro.
In other news, so long as you have appropriate bootable recovery media (once known as a floppy disk with a linux bootloader on it, now a live distro on CD or USB drive), you're not "locked out" of anything.

The x86 boot process is complicated and somewhat fragile, and so (IMO anyway) is it's successor UEFI. This is why most proprietary operating systems offer the user no opportunity whatsoever to screw it up, by simply assuming there is only one OS installed.

Grub is at least nice enough to give you some control over it's installation and options to boot multiple operating systems, though in absence of os-prober by default you will need to explicitly enable / configure the latter.
In any case, if you want multiboot, you'd do well to do at least some basic reading on how the boot process works and have a live USB handy to fix things if you need to.

FWIW I think the decision to disable os-prober by default is kinda silly, but it's not a big deal to re-enable it or otherwise add entries to the bootloader after the fact. There are comments in the relevant configuration files, and the documentation (either online or via man and info) is extensive.

WDstudios wrote:

ESP? Extrasensory perception?

Somewhat obviously, no. EFI System Partition, only relevant if you are using (U)EFI boot.

Last edited by steve_v (2023-10-24 04:41:54)


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