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I have two SSDs in my PC, one with a working Windows 10 on, and the other a fresh install of Antergos.
Booted Antergos up to get grub set up with both installs, but having difficulties there.
I have mounted Windows via the file manager, so I can see all my Windows files. I have then ran sudo grub-mkconfig -o /boot/grub/grub.cfg which unfortunately does not pick up Windows.
Generating grub configuration file ... Found theme: /boot/grub/themes/Antergos-Default/theme.txt Found Intel Microcode image Found linux image: /boot/vmlinuz-linux Found initrd image: /boot/initramfs-linux.img Found fallback initramfs image: /boot/initramfs-linux-fallback.img done Tried running os-prober, and that also does not find it. Drive information

Not sure if anything there is massively incorrect. But this SSD previously had Debian on until today. So I have dual boot working fine before.

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The problem is not easy to solve correctly while each device and distro has its own unique but I'll make a try

when you mounted the windows partition go to terminal and check on what partition windows is mounted by

fdisk -l

in the output notice the partition that has NTFS file system (mostly is only used by windows) let's say it's (e.g /dev/sdb2)

then

ls -l /dev/disk/by-uuid

then take the little string you find that is associated with your partition (e.g /dev/sdb2) the string will be something like (AC46D28646D250A6)

now edit /etc/grub.d/40_custom in your favorite text editor (if not found then you need to find a file that's responsible to add boot entry in your linux distro)

at the bottom of 40_custom add this lines by replacing my string of(AC46D28646D250A6) with your own ofcource

menuentry 'Windows 10' {
    insmod ntfs
    insmod ntldr
    insmod part_msdos
    insmod search_fs_uuid
    search --fs-uuid --no-floppy --set=root AC46D28646D250A6
    ntldr /bootmgr
}

then go to /boot/grub2 and make a backup of your current grub.cfg and now

grub2-mkconfig --output=/boot/grub2/grub.cfg

and make a reboot to check if windows is added now to your boot entry menu

and also notice that the options provided in 40_custom(or your unique file) may have to be changed in order to match your machine state

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  • The Antergos installation is on a GPT-partitioned disk that has /boot/efi on it. This is a pretty strong hint that Antergos is booting in EFI style. The Windows system disk has MBR partitioning, indicating that Windows is booting in old BIOS style. The ntldr GRUB command comes from similarly-named GRUB module, which only exists in i386-pc (=BIOS) version of GRUB, not in the EFI version. So unfortunately I don't think this is going to work in this case.
    – telcoM
    Oct 21 '18 at 23:30
  • @telcoM What is weird here is that the SSD that has Linux on has, previously had Antergos on, then Debian and now going back to Antergos (which is where the issue started), no changes have been made to Windows. Can you think of a way to get Antergos to work with the Windows drive without making changes to the drive itself? I have checked through the BIOS settings and can't see anything that jumps out at me as an issue.
    – Fenwick17
    Oct 22 '18 at 7:13
  • @louay-alosh this is something I was looking at doing, but wasn't too sure of the correct steps. Thanks for the write up, I will look into this.
    – Fenwick17
    Oct 22 '18 at 7:14
  • When starting an operating system installer from e.g. a DVD, modern EFI-capable systems can show two boot options for it: one for legacy BIOS boot style, and another for EFI. Unfortunately it is not always clearly identifiable which is which. Even more unfortunate is that the boot method of the installer will usually also decide the boot method of the OS to be installed: an installer started in BIOS style has no access to firmware EFI boot variables and so cannot fully install an EFI style bootloader. An installer booted in EFI could perform a legacy installation but has no reason to.
    – telcoM
    Oct 22 '18 at 7:36
  • @telcoM Interesting. Since my BIOS settings are exactly what they were when I installed Windows 10, which appears to be in the old style. I would have assumed that means Linux would load the old boot style? My main source of confusion is I installed Debian last week, to the same drive I am installing Antergos to, and it was all smooth. Granted different Linux, but would have though its similar in installation Would it be easier to install Windows 10 with UEFI?
    – Fenwick17
    Oct 22 '18 at 8:55

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