Make Grub find a Windows partition

I have Linux installed on sda and Windows 10 installed on sdb. Both disks are EFI and I want to make Grub add Windows to the boot menu.

I am using CRUX 3.7 at the moment. So… First, install os-prober, available from contrib:

prt-get depinst os-prober

In my case, the EFI boot partition of Windows is sdb1, as reported by fdisk -l:

Device          Start        End    Sectors   Size Type
/dev/sdb1        2048     206847     204800   100M EFI System
/dev/sdb2      206848     239615      32768    16M Microsoft reserved
/dev/sdb3      239616 1948339888 1948100273 928.9G Microsoft basic data
/dev/sdb4  1948340224 1953523711    5183488   2.5G Windows recovery environment

It should be mounted somewhere, so do as root:

mkdir -p /mnt/win

mount /dev/sdb1 /mnt/win

Then, simply run:

grub-mkconfig > /boot/grub/grub.cfg

In the output, there should be this:

Found Windows Boot Manager on /dev/sdb1@/EFI/Microsoft/Boot/bootmgfw.efi

That’s it.

I have my own, custom /etc/default/grub, which will be discussed in another post.