Arch Linux

chaoswizard

Member

Registered: 2020-05-11

Posts: 6

[SOLVED] Dual boot with 2 disks and others questions

Hello everyone,

I just have a brand new computer and I plan to install a dual boot Archlinux / Windows 10 with:

• Archlinux on one drive

• Windows 10 on a second drive

• UEFI boot mode

• Secure boot disabled

I read the wiki and some forum posts but I don't ready understand if it's possible to use one EFI partition per drive (one for Arch and one for Win), then boot on GRUB and be able to choose which OS to boot.
On some forum posts, users recommend to use only one EFI for both OS but, if possible, I prefer to separate them.

I also have others questions around dual booting:

1. Is it possible to have separate EFI partitions and use GRUB to choose which OS to boot?
2. I will use LUKS to encrypt my Arch / and /home partitions: do I need a separate non-encrypted /boot partition or does /boot/EFI have the necessary stuff (initramfs) to decrypt the other ones?
3. I read that is possible to use dislocker or cryptsetup to mount Bitlocker encrypted partitions on Arch.
    Do you have any feedback about them? Are they working fine or should I avoid them?

Thanks.

Last edited by chaoswizard (2022-01-26 15:47:51)

Roken

Member

From: South Wales, UK

Registered: 2012-01-16

Posts: 1,281

Re: [SOLVED] Dual boot with 2 disks and others questions

It's very possible, it's how I have mine set up.

My grub.cfg entry is

menuentry 'Windows' --class windows --class os $menuentry_id_option 'osprober-efi-10B8-0371' {
	savedefault
	insmod part_gpt
	insmod fat
	insmod ntfs
	set root='hd2,gpt3'
	search --no-floppy --fs-uuid --set=root 10B8-0371 
	chainloader /efi/Microsoft/Boot/bootmgfw.efi
}

You will, of course, need to adjust the drive map and UUID to suit your system. You can eliminate savedefault if you do not intend to use a saved entry in grub.

Disconnect the Arch drive whilst you install Windows, and disconnect the Windows drive whilst you install Arch. You will probably need to add a custom entry in /etc/grub.d/ for the Windows grub entry and disable os-prober in /etc/default/grub. The custom grub.d/entry should be 40_custom.

---

Ryzen 5900X 12 core/24 thread - RTX 3090 FE 24 Gb, Asus Prime B450 Plus, 32Gb Corsair DDR4, Cooler Master N300 chassis, 5 HD (1 NvME PCI, 4SSD) + 1 x optical.
Linux user #545703

/ is the root of all problems.

Vizitor

Member

Registered: 2015-01-05

Posts: 83

Re: [SOLVED] Dual boot with 2 disks and others questions

You can install Arch on one disk ( with only "ESP" and "/"  patitions;  with "/" encrypted )
In this scenario You don't have to use Grub. Use efistub, and, on computer startup, use "motherboard boot menu" - Common keys for accessing the Boot Menu are Esc, F2, F8, F10 or F12, depending on the manufacturer of the computer or motherboard. The specific key to press is usually specified on the computer's startup screen.

chaoswizard

Member

Registered: 2020-05-11

Posts: 6

Re: [SOLVED] Dual boot with 2 disks and others questions

@Roken: thanks to confirm that is possible to use separate EFI partitions an use GRUB to boot Arch or Windows

@Vizitor: the Arch GRUB wiki page indicates that is only possible to use encrypted /boot with LUKS1 only (not with LUKS2)
So I will probably use the following partionning scheme:

/dev/sda1 EFI/FAT32 /efi 512 Mio
/dev/sda2 Linux/ext4 /boot 512 Mio
/dev/sda3 luks2
  -- LVM
    -- vg0
      -- swap 8 Gio
      -- root Linux/ext4 / 64 Gio
      -- home Linux/ext4 /home +free

Vizitor

Member

Registered: 2015-01-05

Posts: 83

Re: [SOLVED] Dual boot with 2 disks and others questions

@chaoswizzard
a lil too late answer, but it is just a noticing;
my suggestion was NOT TO USE GRUB at all;
So You can have

/dev/sda1  EFI/FAT32  /boot  (notice that Efi System Partition is mounted on /boot )
/dev/sda2  luks2

chaoswizard

Member

Registered: 2020-05-11

Posts: 6

Re: [SOLVED] Dual boot with 2 disks and others questions

Hello ,

@Vizitor: I finally use GRUB which works pretty fine

@Roken: I simplify your GRUB config to use the following one

menuentry 'Windows 10' {
    search --fs-uuid --no-floppy --set=root 4737-89A3
    chainloader (${root})/EFI/Microsoft/Boot/bootmgfw.efi
}

Everything is working now, thanks.

Head_on_a_Stick

Member

From: The Wirral

Registered: 2014-02-20

Posts: 8,271

Website

Re: [SOLVED] Dual boot with 2 disks and others questions

You can simplify it even further to

menuentry 'Windows' {
   search.fs_uuid 4737-89A3
   chainloader /EFI/Microsoft/Boot/bootmgfw.efi
}

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Para todos todo, para nosotros nada