Guide: Booting Omarchy on a legacy-BIOS-only laptop (no UEFI) with GRUB

[alok123t]

System details: Sony Vaio SVE15118FNB, Intel i7 (3rd gen, no AVX2), AMD Radeon HD 7650M, legacy BIOS only, Omarchy ISO downloaded 2026-10-23

I installed Omarchy on an older laptop whose firmware has no UEFI mode at all (Sony Vaio SVE15118FNB, InsydeH2O BIOS, 2012). The installer completed fine, but the installed system would not boot. Here's what happened and what got it booting, in case it helps anyone else on legacy-only hardware.

Symptoms

• The installer finishes normally ("installed in ~6 min").
• With the USB removed, the laptop shows a blinking cursor and then restarts in a loop.
• With the USB still in, it keeps booting back into the installer menu (entries labelled (x86_64, BIOS)). "Boot existing OS" just loops back to the same menu.
• The firmware has no Boot Mode / UEFI option anywhere, so switching to UEFI isn't possible.

What I tried first

The installer sets up Limine for UEFI. From the live USB I chrooted in and ran limine bios-install /dev/sda, with limine-bios.sys and limine.conf in the root of the boot partition. That got past the blinking cursor, but then I got a blank screen for ~10 seconds followed by a reset. No Limine menu appeared, even with timeout: 10 and textmode: yes.

What worked: GRUB (BIOS) + the stock Arch kernel

I changed two things at once, so I can't say which one was the actual blocker: the bootloader (Limine BIOS → GRUB i386-pc) or the kernel (linux-omarchy → stock linux). The CPU is an older i7 without AVX2, in case that's relevant for the kernel.

Replace sdX with your disk. Mine was sda: sda1 FAT32 boot partition, sda2 LUKS.

1. Boot the Omarchy USB, choose the install medium, then press Ctrl+C to leave the installer.
2. Connect to the network (iwctl → station wlan0 scan → station wlan0 connect "SSID").
3. Unlock and enter the install:

   cryptsetup open /dev/sdX2 root
   mount -o subvol=@ /dev/mapper/root /mnt
   mount /dev/sdX1 /mnt/boot
   arch-chroot /mnt
   

4. Install GRUB for BIOS and the stock kernel:

   pacman -Sy grub linux
   grub-install --target=i386-pc /dev/sdX
   

5. The kernel lands in /boot/<machine-id>/linux/. Copy it to simple names:

   cp /boot/*/linux/vmlinuz /boot/vmlinuz-linux
   cp /boot/*/linux/initramfs /boot/initramfs-linux.img
   

6. Write /boot/grub/grub.cfg. Get the FS UUID with blkid /dev/sdX1 and the PARTUUID with blkid /dev/sdX2. The kernel options match what's in Omarchy's limine.conf:

   set timeout=5
   insmod part_msdos
   insmod fat
   search --no-floppy --fs-uuid --set=root <SDX1-UUID>
   menuentry "Omarchy" {
     linux /vmlinuz-linux cryptdevice=PARTUUID=<SDX2-PARTUUID>:root root=/dev/mapper/root rootflags=subvol=@ rootfstype=btrfs rw
     initrd /initramfs-linux.img
   }
   

7. exit, reboot, remove the USB. The GRUB menu shows, then the LUKS prompt, then Hyprland.

Keep the copies updated. Kernel updates write to the <machine-id> folder, not to the copies GRUB boots. A pacman hook like this one at /etc/pacman.d/hooks/zz-grub-kernel.hook refreshes them:

[Trigger]
Type = Package
Operation = Install
Operation = Upgrade
Target = linux
Target = mkinitcpio

[Action]
Description = Copying kernel for GRUB
When = PostTransaction
Exec = /bin/sh -c 'cp /boot/*/linux/vmlinuz /boot/vmlinuz-linux && cp /boot/*/linux/initramfs /boot/initramfs-linux.img'

Suggestions for Omarchy

• Have the installer detect a BIOS-only boot (no /sys/firmware/efi) and either install a working BIOS bootloader or warn before wiping the disk.
• If linux-omarchy targets newer CPUs (x86-64-v3 / AVX2), say so in the requirements. I haven't confirmed that this was the cause here.

Side note

Hyprland ran fine once booted. Later the laptop's Radeon HD 7650M (its only GPU) started failing its ring test on every boot, so the desktop stopped working. That looks like a hardware failure on a 13-year-old GPU and isn't related to the boot issue above.