Arch Linux

mytArch

Member

Registered: 2024-11-16

Posts: 18

[SOLVED] MBR entry causing problems with my boot loader?

I have an SSD (say sdb) which previously had another linux distro installed, and whenever I attempted to boot into my arch linux (installed on a different ssd say SDA) with sdb connected, the attempt would fail (after previously working without incident).
I would need to reinstall the boot loader (without sdb disconnected) to get back into arch linux on sda.
(With better knowledge / skill I might simply have fixed something on the  sda efi partition, but my efi-bios simply 'forgot' / 'couldn't see' the arch linux boot loader on sda, until I reinstalled it - though looking at the efi partition it was of course there all along.)

So I erase sdb, remove partitions, reformat - still the above.

So I erase the sdb MBR, remove partitions, reformat - now I can boot into arch linux with this disk connected and no problems.

So I'm thinking there was something in the sdb MBR, now removed, that was causing the above.

Thoughts, comments?

Last edited by mytArch (2025-01-11 06:53:31)

Head_on_a_Stick

Member

From: The Wirral

Registered: 2014-02-20

Posts: 8,738

Website

Re: [SOLVED] MBR entry causing problems with my boot loader?

Booting in UEFI mode would cause the firmware to ignore the MBR region.

Non-permanent NVRAM boot entries are a quite common bug in UEFI implementations. Most bootloaders offer a workaround for this, check their wiki pages for details and see https://www.rodsbooks.com/efi-bootloade … ive-naming for more on this.

https://wiki.archlinux.org/title/Unifie … ly_removed could be a factor here.

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Para todos todo, para nosotros nada

mytArch

Member

Registered: 2024-11-16

Posts: 18

Re: [SOLVED] MBR entry causing problems with my boot loader?

Thanks, I'll have a read of that material, but off the top of my head:

Not 100% certain but I suspect that the connection / disconnection of the non-arch-linux drive was linked with the disappearance of my arch boot loader from the efi-bios menu.

Do you think that I'm mistaken there, or that perhaps an efi boot loader on the non-arch drive survived partition deletion / creation of new partitions and reformatting?

Last edited by mytArch (2025-01-09 21:35:13)

Head_on_a_Stick

Member

From: The Wirral

Registered: 2014-02-20

Posts: 8,738

Website

Re: [SOLVED] MBR entry causing problems with my boot loader?

EFI loaders should only be read from EFI system partitions, although some firmware implementations are more fussy than others. If there aren't any partitions then there aren't any EFI loaders.

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Para todos todo, para nosotros nada

V1del

Forum Moderator

Registered: 2012-10-16

Posts: 23,897

Re: [SOLVED] MBR entry causing problems with my boot loader?

Many mainboards will remove "unavailable" entries when you disconnect a drive that had an explicit reference in their NVRAM table, the details of which are explained in the second link HoaS gave you

mytArch

Member

Registered: 2024-11-16

Posts: 18

Re: [SOLVED] MBR entry causing problems with my boot loader?

Thanks Head / V1del.
I'm marking this solved as I'm no longer having this problem, and, while none of the referenced material I've gone through so far explains the problem as I recall it, I don't think it's useful to anyone else to read 'I don't think that's what happened' when I can't back this up with data on the current state of my system.

Last edited by mytArch (2025-01-11 07:29:59)