Dual boot Fedora <--> Windows 8

[Chris Murphy]

On Nov 22, 2013, at 3:25 AM, Andre Costa <blueser at gmail.com> wrote:

> Hi,
> 
> I have the following partitions on a 1TB disk:
> 1M BIOS boot partition
> 500M Linux boot partition
> 733G Linux LVM partition (Fedora 19)
> 200G unused space
> I would like to install Windows 8 on this last partition. Anyone knows if this will mess up with my current boot manager? Can Windows 8 coexist with GRUB?

Yes and no. The first 440 bytes of the first sector, LBA 0, cannot be shared. Only one bootloader can exist there at a time, either Windows or GRUB. This 440 bytes of GRUB code was called stage1, it's now called boot.img, and it baked in the LBA it's supposed to jump to next. For the Windows stage1 equivalent, it jumped conditionally to the start LBA for the partition in the MBR with an active bit set.

Because you're using BIOS Boot, it's possible grub-install put core.img (formerly stage2) right at the start of that partition, in which case by merely changing the boot flag (the active bit), you could choose which OS is loaded. But it's not guaranteed that grub-install will put core.img right at the start of that partition.

So I suggest you install Windows, let it blow away GRUB's boot.img on LBA0, reboot from Fedora install media - ideally either netinstl or DVD because you can choose the rescue option which will mount everything correctly so that all you have to do is:

chroot /mnt/sysimage
grub2-install /dev/sdX
grub2-mkconfig -o /boot/grub2/grub.cfg
exit
reboot

Where X is probably an a if this is the only drive on the computer. If you only have live desktop media handy then you get to setup the mounts yourself and since you're using LVM it makes it more complicated since you need to check if the LVs are active, and find their names, and mount them all in the right sequence:

mount /dev/mapper/fedora-root /mnt/sysimage
mount /dev/sda2 /mnt/sysimage/boot
mount -B /dev /mnt/sysimage/dev
mount -B /proc /mnt/sysimage/proc
mount -B /sys /mnt/sysimage/sys

And then the same as above starting with chroot. Reinstalling grub will toast the Windows 440 bytes in LBA 0. And rerunning grub2-mkconfig *should* cause it to call OS-PROBER, find Windows, and create a GRUB entry for it automatically. 


Chris Murphy
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.fedoraproject.org/pipermail/users/attachments/20131122/5d7d2a59/attachment.html>