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

[Joseph Emenaker]

On 5/17/2013 8:17 AM, Phillip Susi wrote:
> You don't seem to have understood the passage you quoted. Let me try 
> rephrasing it: when you boot from the livecd and update grub, you 
> first chroot into the hard drive, so you are running the update-grub 
> version on the hd, not the cd.

True, looking back through it, I think I misinterpreted it. I took the 
original idea to be "use the mode (UEFI vs BIOS) which was used for this 
current boot session". You can generate a grub.cfg for another system 
without needing to chroot. grub-mkconfig lets you redirect the output to 
any file you want. So, what's to prevent a user from booting a recovery 
CD and, without using chroot, using:

grub-mkconfig -o /media/MyRealUbuntuPartition/boot/grub/grub.cfg

> We're not going to support having both installed at the same time and
> using the same config.  You need to pick which mode you want to use
> and stick with it, not flip flop every other boot.  In addition,
> Windows can not be booted in bios mode on a GPT disk, so you have to
> use grub-efi anyhow.

But other OS's *can*. I can boot my linux partitions in UEFI or BIOS 
mode. Furthermore, linux is what I turn to when I have trouble booting 
any of my partitions. If I can just get to a linux prompt, with 
fdisk/parted/grub/etc, then I can usually fix any other booting 
problems. So, it would be helpful to be able to boot a linux partition 
from BIOS mode if the EFI SP gets hosed. You can choose not to support 
that; that's your choice, but I think there are scenarios wherein it 
would be useful.

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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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