GRUB can only access 128 GiB during MBR boot (Was: GRUB 2.12 fails to access ext4 filesystem during MBR root while UEFI boot works)

[Markus Laire]

No, that wasn't it.

With further testing I've noticed that GRUB can't access anything
beyond the first 128 GiB of the USD SSD during MBR boot, but there is
no such limitation during UEFI boot. For example if I place "BIOS Boot
Partition" beyond 128 GiB, then GRUB just shows text "GRUB" and can't
even get to the command line.

Could this be some strange BIOS limitation?

On Fri, Jan 30, 2026 at 12:36 AM Pascal Hambourg <pas...@plouf.fr.eu.org> wrote:
>
> On 29/01/2026 at 17:16, Markus Laire wrote:
> > I have a problem where GRUB 2.12 fails to access ext4 filesystem, but
> > only during MBR root, not during UEFI boot.
>
> Maybe you need to insmod ext2 ?

-- 
Markus Laire