> At update-grub time, you know if you are EFI and should search for an EFI bootable windows.
No, don't rely on the mode where grub-update is used !
Counter-examples:
1) Windows is installed in UEFI mode but update-grub is used from a Ubuntu32bit liveCD (which cannot be booted in UEFI mode, see Bug #1025555 ).
2) Windows is installed in UEFI mode, but update-grub is used from a Legacy mode live-session because the BIOS is set up to boot the CD/USB in Legacy mode
3) Windows is installed in Legacy mode, but update-grub is used from an UEFI mode live-session because the BIOS is setup to boot the CD/USB in UEFI mode.
> an EFI booting system can't have a bios booting windows install.
> At update-grub time, you know if you are EFI and should search for an EFI bootable windows.
No, don't rely on the mode where grub-update is used !
Counter-examples:
1) Windows is installed in UEFI mode but update-grub is used from a Ubuntu32bit liveCD (which cannot be booted in UEFI mode, see Bug #1025555 ).
2) Windows is installed in UEFI mode, but update-grub is used from a Legacy mode live-session because the BIOS is set up to boot the CD/USB in Legacy mode
3) Windows is installed in Legacy mode, but update-grub is used from an UEFI mode live-session because the BIOS is setup to boot the CD/USB in UEFI mode.
> an EFI booting system can't have a bios booting windows install.
I am nearly sure of the contrary, because many preinstalled Windows come with both files to be booted in UEFI and Legacy modes. paste.ubuntu. com/1495850, http:// paste.ubuntu. com/1479512 , http:// paste2. org/p/2700549
Examples: http://