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#1 2021-02-12 16:21:11

wjatscheslaw
Member
Registered: 2021-02-12
Posts: 6

[SOLVED] Separate Boot Partition on Bios/MBR

Hi
Is it possible to install arch with a separate boot partition using MBR?
If possible, can someone please explain me how to partition, mount the boot partition and how to install grub on it?

Partitioning and installing grub are the two only things that always confuses me.

Last edited by wjatscheslaw (2021-02-12 20:38:52)

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#2 2021-02-12 16:58:55

V1del
Forum Moderator
Registered: 2012-10-16
Posts: 12,708

Re: [SOLVED] Separate Boot Partition on Bios/MBR

You can but there'd be little point to it unless you'd need an unencrypted store for the boot loader and kernel image and encrypt the rest with a method GRUB isn't compatible with, i.e. LUKS 2

If it's just about a normal installation then the "boot partition" will house the GRUB config files, assuming you are using a filesystem supported by GRUB it doesn't matter whether that's a separate partition or the normal root partition. You are going to install GRUB into the MBR section of your disk then boot the MBR section and GRUB will then load it's further configuration files from your boot partition.

This sounds XY-Problem-ish, what's your actual intention here? Why do you think you need a separate boot partition?

Last edited by V1del (2021-02-12 17:00:33)

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#3 2021-02-12 18:24:22

wjatscheslaw
Member
Registered: 2021-02-12
Posts: 6

Re: [SOLVED] Separate Boot Partition on Bios/MBR

Yes my goal is to have encrypted root and home partitions.
There is one more thing. At the moment I'm still trying to install arch in gnome-boxes. So maybe it is a problem because of the virtual machine.

What I've done so far is:
=> partitioned the hard drive with fdisk
    created dos partition table
    512M boot partition with the type "ef" (EFI (FAT-12/16...) as /dev/sda1
    the rest of the drive is set to a partition with the type "83" (Linux) as /dev/sda2
=> mount partitions
    mount /dev/sda2 /mnt
    pacstrap /mnt base linux linux firmware
    mount /dev/sda1 /mnt/boot
...
=> install grub
    grub-install /dev/sda
    grub-mkconfig -o /boot/grub/grub.cfg
...

My problem is, that after installing grub, the system won't boot instead I get the grub prompt

Last edited by wjatscheslaw (2021-02-12 18:29:13)

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#4 2021-02-12 18:29:33

Trilby
Inspector Parrot
Registered: 2011-11-29
Posts: 25,237

Re: [SOLVED] Separate Boot Partition on Bios/MBR

Ah, first, you should have specified that you were referring to an EFI partition, not just a boot partition especially given that you said Bios/MBR.  Second, and perhaps more importantly, why are you using MBR for an EFI system?  And you do realize that EFI partitions would not be used at all for bios/MBR systems (as indicated in your title).  Bios and EFI are mutually exclusive - and while EFI can be done on MBR, it's not as common as EFI systems generally use GPT.

EDIT: also, if the above is all you've done there are other issues.  You need to create filesystems on the partitions.  What tutorial are you trying to follow for your installation?  You should only follow the installation guide on our wiki.

Last edited by Trilby (2021-02-12 18:33:42)


"UNIX is simple and coherent..." - Dennis Ritchie, "GNU's Not UNIX" -  Richard Stallman

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#5 2021-02-12 18:36:49

wjatscheslaw
Member
Registered: 2021-02-12
Posts: 6

Re: [SOLVED] Separate Boot Partition on Bios/MBR

Since there is no "/sys/firmware/efi/efivars" it means that the system booted in BIOS, am I right?
Which type should I use for the boot partition when the system is booted into BIOS instead of UEFI?

I'm following the arch wiki install guide for the main part, but as I said, I'm kinda lost when it comes to partitioning and installing grub in BIOS/MBR

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#6 2021-02-12 18:43:09

Trilby
Inspector Parrot
Registered: 2011-11-29
Posts: 25,237

Re: [SOLVED] Separate Boot Partition on Bios/MBR

wjatscheslaw wrote:

Since there is no "/sys/firmware/efi/efivars" it means that the system booted in BIOS, am I right?

Yes.  Unfortunately it seems most guidance of BIOS/MBR systems has been removed from the installation guide.  The boot partition on a bios system should be a "linux" partition type and must have a filesystem.  I'd suggest ext4 as the filesystem if you don't know about the alternatives.


"UNIX is simple and coherent..." - Dennis Ritchie, "GNU's Not UNIX" -  Richard Stallman

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#7 2021-02-12 19:11:12

wjatscheslaw
Member
Registered: 2021-02-12
Posts: 6

Re: [SOLVED] Separate Boot Partition on Bios/MBR

I've now tried with "linux" partition type and made the filesystem to ext2, because I've read before that it makes more sense to go with ext2 than ext4 for the boot partition, but I still get the grub prompt and can't boot into arch.

Maybe the problem is how I'm installing the grub bootloader?
I did "genfstab -U /mnt >> /mnt/etc/fstab" when installing arch and made sure that the drives would be mounted by the system when restarting the machine.

What is the difference between the type I choose when partitioning with fdisk and the filesystem I format the partitions later with? Why does it matter choosing "linux" instead of "efi" or any other partition type? (maybe I should put it into a new question)

Last edited by wjatscheslaw (2021-02-12 19:12:33)

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#8 2021-02-12 20:01:47

Scimmia
Bug Wrangler
Registered: 2012-09-01
Posts: 8,494

Re: [SOLVED] Separate Boot Partition on Bios/MBR

The partition type really doesn't matter. The filesystem does, as your fstab will be wrong when you change it.

The big problem I see with the procedure you posted is that you mounted it after pacstrap. So things were installed to /mnt/boot, then you masked them by mounting an empty partition there.

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#9 2021-02-12 20:37:44

wjatscheslaw
Member
Registered: 2021-02-12
Posts: 6

Re: [SOLVED] Separate Boot Partition on Bios/MBR

It worked. The problem was that I mounted the boot partition after pacstrap. Thank you all for your help!

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