Upgrading Windows on a Linux laptop

[Chris Murphy]

On May 11, 2014, at 9:14 AM, Timothy Murphy <gayleard at eircom.net> wrote:

> I rarely use Windows on my dual-boot Fedora-20/KDE laptop,
> but I'd like to update Windows XP to Windows 7 now.
> 
> I found when I did this on a CentOS machine
> I was unable to get back to Linux,
> and had to re-install CentOS.
> I don't understand why, as I had saved and re-installed the MBR.

You saved and reinstalled it how? It should just be grub-install <dev> or grub2-install <dev> (CentOS and Fedora respectively).

> 
> Am I wrong in thinking that this should be sufficient?
> If not, what else do I need to save?

Windows 7 will step on the first 440 bytes of the MBR with its own boot strap code, so Windows will boot but GRUB will not load and thus you don't be able to get to Linux. So you need to have a Fedora 20 install disk handy. The easiest is either netinstall or DVD, because they have an anaconda rescue boot option under the troubleshooting menu. This rescue boot is nice because it finds the Linux system, and mounts all of its parts correctly at /mnt/sysimage. So all you have to do is:

chroot /mnt/sysimage
grub2-install --no-floppy /dev/sda

--no-floppy will go faster and it also avoids baking in a floppy driver into core.img allowing it to be smaller.


If you use a Live CD/DVD, then you have to find and mount all the parts of your Linux installation correctly, including bind mounting proc and dev, and maybe sys and run also, for the benefit of grub2-install.


Chris Murphy