I just got my new working notebook with Windows 8 pre-installed. After installing Ubuntu 12.10 the grub menu says that there is an "invalid EFI file path" and it won't boot Windows. Ubuntu works fine...
Is there anything I can do about this?
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Boot Repair solved it for me.
Go to your boot options (F12 or etc) and boot your liveCD or liveUSB. Make sure that you boot in UEFI (Ex. "UEFI: CD/DVD" or "UEFI: [USBname]"). Select "Try Ubuntu." Get Boot Repair and select "recommended repair."
Link: Ubuntu Boot Repair
Note: Make sure that you boot the CD or USB in UEFI. I ran Boot Repair without being in UEFI mode and I got Grub, but Windows 8 would not boot.
Hope this helps!
From the grub.cfg you posted it looks like you've done a lot of messing with grub to try to get this working, I recommend that you start by cleaning all of this up and going back to a default grub configuration (which will probably have no entry for Windows at all in the grub.cfg) and then create a file /boot/grub/custom.cfg with this for contents:
In the long term, hopefully os-prober and grub-mkconfig will gain support for detecting UEFI based Windows installations (at which point this entry will become redundant, and you can simply delete /boot/grub/custom.cfg)
you should try to add windows as workaround manually to grub.
At first run
Here you should see the UUID from your windows partition
open /etc/grub.d/40_custom and paste/edit following code but replace UUID_FROM_WIN8 with your UUID mentioned above.
The chainloader should look the same for all windows versions, as far as i know..
After editing grub files you have to run
Please test it first and give me some feedback because it could be possible that the efi file won't be found.. but i don't want to give multiple advice in one answer..
hope this helps!