So I decided to dual boot kali linux and windows 8. I follow the tuts in here http://docs.kali.org/installation/dual-boot-kali-with-windows

But when everything is done and I reboot, grub not showing windows option and boot kali linux instead of windows, any help?

/dev/sda1 fat32, efi system partition
/dev/sda2 unknown, microsoft reserved
/dev/sda3 ntfs, where i install win 8
/dev/sda4 unknown, bios_grubs
/dev/sda5 ext 4, the root
/dev/sda6 linux swap

Already tried: updating grub, editing grub in etc/default

  • Did you try using os-prober, then regenerating the grub config files?
    – user49730
    Nov 21 '15 at 17:25

You said your /dev/sda4 partition is for bios_grub. That would indicate that you may be booting Kali via UEFI's compatibility support module, using a legacy BIOS boot scheme. A boot loader that uses BIOS boot scheme cannot switch back to UEFI boot loaders, since the compatibility support module has already hidden away the UEFI boot services any UEFI bootloader will need. And since a UEFI-based Windows won't necessarily have a BIOS-based bootloader installed, there might not be a BIOS-based Windows bootloader for os-prober to detect.

With that configuration, the only way to switch between booting Windows and Kali would be via the UEFI BIOS settings. For each native UEFI bootloader, there should be a new boot option created: for Windows, its description text should be something like "Windows Boot Manager". That would be the "best" choice for booting UEFI-based Windows.

The proper way to install an UEFI-bootable operating system (including any UEFI-capable Linux distribution) is to boot from the operating system's installation media in UEFI mode. This way, the installer can detect the presence of UEFI and add the new bootloader to the firmware settings. If the installer is started in legacy BIOS mode, then it will not have a way to access UEFI at all.


You could try using the os-prober utility which probes the disk for another operating system and adds it to the bootloader.

$ os-prober

When it's done, run update-grub.

  • 1
    The grub-common package in debian (and derivatives) includes an /etc/grub.d/30_os-prober file, which automatically runs os-prober if it is installed and generates appropriate grub.cfg entries when update-grub is run.
    – cas
    Nov 22 '15 at 0:23

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