Install OS-Prober
sudo pacman -S os-prober
Run it:
sudo os-prober
Output:
/dev/sda2@/efi/Microsoft/Boot/bootmgfw.efi:Windows Boot Manager:Windows:efi
Enable os-prober in grub
Edit /etc/default/grub
Add GRUB_DISABLE_OS_PROBER=false
Update grub
1 | sudo grub-mkconfig -o /boot/grub/grub.cfg |