[bug #31979] Possibility to load UEFI x64 Windows Boot Manager

[Rajko Stojadinovic]

URL:
  <http://savannah.gnu.org/bugs/?31979>

                 Summary: Possibility to load UEFI x64 Windows Boot Manager
                 Project: GNU GRUB
            Submitted by: rajkosto
            Submitted on: Sat 25 Dec 2010 10:51:31 PM GMT
                Category: Booting
                Severity: Major
                Priority: 5 - Normal
              Item Group: Feature Request
                  Status: None
                 Privacy: Public
             Assigned to: None
         Originator Name: Rajko Stojadinovic
        Originator Email: address@hidden
             Open/Closed: Open
         Discussion Lock: Any
                 Release: 
                 Release: Bazaar - trunk
         Reproducibility: Every Time
         Planned Release: None

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Details:

I have installed uefi GRUB from latest bzr trunk compiled from source and
it's working good to boot linux and the EFI shell. However, it will not boot
the Windows Boot Manager (bootmgfw.efi) by using the chainloader directive.
All i get then is 2 hdd accesses, and then a black screen. I can press
ctrl-alt-del at this point to restart the computer. The bootmgfw.efi runs fine
when i boot it directly from the firmware boot manager, or if i boot the efi
shell from the firmware boot manager, and then run bootmgfw.fw. However, if
GRUB has been loaded in any step between those (like
GRUB->Shell->Bootmgfw.efi), it will only display a black screen. phcoder
suspects this is because GRUB is holding on to allocated memory, in order to
support EFI return on exit feature. Is it possible to implement a command like
chainloader for .efi files, but one that frees as much memory as possible
before transferring execution to the .efi file ? This should make booting
Windows Boot Manager work properly.




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