This is, in fact, possible:
- Boot the system using a linux live cd with
gdisk
on it. I used a CentOS 7 Core installation and used recovery mode. I did this by editing the grub boot options and tacking on rescue
to the end.
- Run
gdisk
on the disk with Windows installed. See the gdisk docs for more info.
- Reboot the machine into a Windows installation disk, and open up the command prompt using the
repair your computer
option.
At this point, I had to load the VMWare PVSCSI drivers, and already had the floppy with the drivers mounted. To do this, you can run drvload A:\AMD64\PVSCSI.INI
. Alternatively, you can go through the initial Windows setup, and load the drivers via the GUI. You may then back out and click the Repair your computer
link.
Run the following commands to (with luck) restore the boot loader:
bootrec.exe /FixMbr
bootrec.exe /RebuildBcd
Note that your mileage may vary, and I would definitely at least snapshot the VM before doing this, but a full backup is better.