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

[Phillip Susi]

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On 5/17/2013 12:32 PM, Joseph Emenaker wrote:
> 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

Nothing, just like nothing prevents you from dd'ing /dev/zero all over
your drive.  Don't do that.  If you are trying to get a correct
grub.cfg, then you have to chroot since grub-mkconfig generates a
config to boot the system it finds in the current root.

> 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.

Whether it is useful or not, it isn't related to the subject of this
bug, which is booting windows.


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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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