Fedora and Windows fighting for the bootsector

[Chris Murphy]

On Tue, Dec 16, 2014 at 10:54 AM, Jouk Jansen
<joukj at hrem.nano.tudelft.nl> wrote:
> Hi all,
>
> I have a Toshiba (Satelite C50-B-14C). Window 8 was preinstalled. I turned
> it into a dual boot by shrinking the Windows partition and installing F20.
> All was fine until I installed some Windows-updates the other day. The
> machine then only booted windows. I made Fedora boot again by
> grub2-install/grub2-mkconfig. However now when you select windows in the
> grub menu it will not start because it lost its boot-block.
> I'm not eager to try windows writing its bootsector again, because I'm
> afraid I will loose grub2 again.
> Does anyone know this problem? and how to solve it.

Can you boot Fedora and run

$ efibootmgr

and post the results? I can't tell if this computer has BIOS or UEFI
firmware. I thought all Windows 8 pre-installed hardware are UEFI.

Also, what do you mean by "will not start because it lost its boot
block" - what's the actual error message? If you can take a cell phone
photo and post that somewhere it might be useful to determine if this
is a Windows bootloader error or GRUB error.

On BIOS computers, grub-install only replaces the first 440 bytes of
bootloader code on the 1st sector, none of the other Windows
bootloader stages are touched.

OnUEFI computers, the bootloaders co-exist on the EFI System partition
in different directories. There's no longer such a thing as boot
blocks or boot sectors. And grub2-install should be avoided.


-- 
Chris Murphy