[Bug 1024383] Re: update-grub generates only BIOS based menu entries for Windows, even on UEFI systems

[Jordan]

I've changed the title to something that I consider correct and
appropriate as the last change was indeed incorrect.

Separately from the title, I wonder if it's possible to have a Windows
installation which is bootable both via BIOS and via UEFI. If so, then
it may not always be clear what type of entry to create at grub-mkconfig
time and so it may be best to create both BIOS and UEFI based entries,
but within an if statement that checks at boot to see if grub itself was
loaded via UEFI or BIOS, and shows only the appropriate menu entry (this
is currently possible, and not even difficult, to do with grub-script).

I don't know what to do though if we have for instance Windows installed
in such a way that it can only be booted via BIOS, but Ubuntu's grub is
being loaded via UEFI. In such a case there is nothing that grub can do
to boot Windows, but just not showing the Windows entry is clearly not
ideal. Possibly showing the Windows entry but giving a *clear* error
message about why it can't be loaded is the solution there.

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https://bugs.launchpad.net/bugs/1024383

Title:
  update-grub generates only BIOS based menu entries for Windows, even
  on UEFI systems

Status in “grub2” package in Ubuntu:
  Confirmed
Status in “os-prober” package in Ubuntu:
  Confirmed
Status in “grub2” package in Debian:
  New

Bug description:
  64bits computer with pre-installed EFI Windows 7. (remark: same bug if
  Windows8)

  Installed Ubuntu 64bits in dual-boot. GRUB (grub-efi) is correctly
  installed and allows to boot Ubuntu, but it does not allow to boot
  Windows.

  Its menu shows 2 INVALID Windows entries. When selecting these
  entries, it displays "Invalid EFI file path" error, and returns to
  GRUB menu.

  It appears that GRUB creates BIOS/mbr entries when it should be
  UEFI/gpt type entries.

  *********************** WORKAROUND **************************

  either boot Windows from the (EFI) BIOS menu, or add valid Windows entries via Boot-Repair.
  ***************************************************************

  (original thread in French: http://forum.ubuntu-
  fr.org/viewtopic.php?pid=10010231#p10010231 )

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