Hi all, I experienced similar problem on an ASUS X20E1 with pre-installed Windows 8 image and UEFI.
I used Wheezy RC1 netinst image fetched from the site and dd-ed to the USB stick. In order to install Debian I had to turn off Secure Boot in ASUS UEFI menu. After I checked if Windows 8 still boots with Secure Boot turned off and it was OK, so I proceeded with Debian installation. Once installed, Debian could boot, but Windows 8 no, because Grub menu entries produced by `od-prober` were wrong. Here are the entries : ### BEGIN /etc/grub.d/30_os-prober ### menuentry "Windows Recovery Environment (loader) (on /dev/sda2)" --class windows --class os { insmod part_gpt insmod ntfs set root='(hd0,gpt2)' search --no-floppy --fs-uuid --set=root F0A837FBA837BF42 drivemap -s (hd0) ${root} chainloader +1 } menuentry "Windows 8 (loader) (on /dev/sda4)" --class windows --class os { insmod part_gpt insmod ntfs set root='(hd0,gpt4)' search --no-floppy --fs-uuid --set=root 86B23B6FB23B633B drivemap -s (hd0) ${root} chainloader +1 } ### END /etc/grub.d/30_os-prober ### Trying to boot these will fail, as bootloader will complain that it does not recognize "drivemap" directive. I tried replacing the entries by : menuentry "Windows (UEFI)" { search --set=root --file /EFI/Microsoft/Boot/bootmgfw.efi chainloader /EFI/Microsoft/Boot/bootmgfw.efi } That helped find `bootmgfw.efi` but went directly into Windows Recovery blue screen, saying that device is not connected and gving an error 0xc000000f. At least this confirms that Windows 8 bootloader was found, but the way it was executed was wrong. To confirm that Windows 8 still boots fine after Debian installation, I changed ASUS UEFI boot menu (i.e. BIOS menu), to boot Windows 8 bootloader directly, and this worked fine, so I deducted that only Grub path to the Windows 8 bootloader is wrong in the grub.cfg. Here is a list of my partitions : root@Mali:/home/drasko# lsblk NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT sda 8:0 0 465.8G 0 disk ├─sda1 8:1 0 300M 0 part /boot/efi ├─sda2 8:2 0 900M 0 part ├─sda3 8:3 0 128M 0 part ├─sda4 8:4 0 97.5G 0 part ├─sda5 8:5 0 93.1G 0 part / ├─sda6 8:6 0 7.5G 0 part [SWAP] └─sda7 8:7 0 266.4G 0 part /home Windows 8 resides on /dev/sda4. I then tried to mount bot Windows partitions : OS and Recovery and look for "bootmgfw.efi" file. On Rrcovery partition it is located in EFI/Microsoft/Boot/bootmgfw.efi, but on OS partition it is located in Windows/EFI/Boot/bootmgfw.efi (or similar), so I tried replacing entries by this path, hoping that it will boot Windows in normal mode, and not give me Recovery screen. The boot starts but immediately fails, with similar message (only that Recovery screen is not showed this time). This potentially might work, maybe some modules were not probed (see below). Finally, I found that solution escribed here worked fine : http://falstaff.agner.ch/2012/12/18/ubuntu-12-10-and-windows-8-with-secure-boot-mode/ This script : https://gist.github.com/falstaff84/4330598/raw/adaf598a78d568dbfada596441bdfad3b4dd3f97/25_windows_uefi seem to be doing a job of broken `os-prober` and creates correct grub.cfg entry : ### BEGIN /etc/grub.d/25_windows_uefi ### menuentry "Windows 8 (loader)" { insmod search_fs_uuid insmod chain insmod part_gpt insmod fat set root='(hd0,gpt1)' search --no-floppy --fs-uuid --set=root BA44-790F chainloader /EFI/Microsoft/Boot/bootmgfw.efi } ### END /etc/grub.d/25_windows_uefi ### It is similar as the workaround proposed in this bug earlier, but I can notice two things here : UUID dieffers and adequate modules are inserted (like `fat` for example). I hope that this helps bug discovery and elimination. Best regards, Drasko -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org