[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 10:38 AM, Joseph Emenaker wrote:
> Phillip Susi wrote:
>> You don't run update-grub from a live session; you have to chroot
>> into the install and run it from there, where you are running the
>> correct version, regardless of how you booted the livecd. ...
> 
> No, I think Yann is absolutely correct about this. My laptop can
> boot in UEFI, BIOS, or a "mixed" mode (where it looks for a UEFI
> partition and then, if not found, looks for a MBR boot record). The
> point, however, is that I can boot SuperGRUB or a live-CD via
> BIOS/MBR booting off of a CD or USB drive, and then mount the linux
> partition on my hard-drive, and then run update-grub from there.
> That would be a case where my computer booted via BIOS/MBR *just*
> for that recovery session, when "normal" booting is going to be
> done via UEFI.

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.  Thus, if you installed the system
originally in efi mode and it has grub-efi installed, and you boot the
cd in bios mode, you are still running the efi version of update-grub
when you chroot into the hd, so the fact that you booted the livecd in
bios mode does not matter.

> But it seems that the more-critical part of the solution would be
> for there to be grub.conf directives specific to MBR and UEFI
> booting. Imagine, for example:
> 
> menuentry "Windows 8" { set root-efi=(hd0,gpt2) set
> root-mbr=(hd0,2) chainloader-efi
> /EFI/microsoft/BOOT/bootmgfw.efi chainloader-mbr +1 }

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.


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-- 
You received this bug notification because you are a member of Ubuntu
Foundations Bugs, which is subscribed to grub2 in Ubuntu.
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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