Windows 8 preinstall downgrade to Win 7: UEFI problems :/

28
2014-03
  • Tim Flemming

    I have a friend who has a HP Laptop with UEFI booting. Due to some unfortunate human error resulting in an unbootable system, I suggested and he agreed to installing Win7 ("I hate the big tile thingys"). So I attacked with Gparted. Wiped the whole drive. Set flags to boot. Set part table as MBR.

    However upon trying to install win7, it still claimed I had a GPT style disk. Unable to install. The only thing i can think of I'm doing wrong is not changing the BIOS/UEFI to legacy.

    My question is, if I enable legacy, somehow get the drive to actually be MBR, and use my X86 DVD, should I be good? Is there some common glitches people miss when dealing with GPT/UEFI? I need some help because he now has a blank laptop which I am responsible for.

    Another question. windows 8 came installed on a GPT disk. So why does it say it can't install to a GPT-style disk, when I boot the install DVD?

    Backstory : He locked himself out of windows 8 (forgot his password)... so he called me. Well, after trying to use the latest version of chntpw in UBCD5.2.6, i came to the conclusion i needed to wipe the drive and install windows 7. A little googling suggested using certain versions of chntpw, but i decided to not waste the time burning endless CDs.

    • Answers
  • Milind R
    1. Windows 7 can use UEFI and GPT-style disks. Why bother going back to MBR? For this, you need a 64-bit version of windows. If you really do want to use MBR, then nothing much to take care of, except the 4 partition rule (primary/extended/logical partitions issue).
    2. The reason Windows is saying it can't install to GPT is because it has been booted in BIOS mode. To boot a DVD in UEFI mode, you'll have to choose to boot from the DVD from an entry prefixed as 'UEFI: SlimType Optiarc ... '. NOT the 'CDROM: ...' or 'P3: ...'. Windows cannot install to GPT in BIOS mode.

    • Related Question

    Is there any way to boot Windows 7/8 using BIOS on GPT?
  • John Chadwick

    I'd like to know if there's a method to get Windows 7 or Windows 8 Developer Preview to install to a GPT disk on my traditional IBM PC BIOS setup. Windows 7, of course, rejects my GPT partition, because I don't have UEFI. Well, Debian and Grub 2 seem to work fine... So I want to know if there's a way to force Windows to work as well.

    I'd seriously prefer avoiding hybrid MBR/GPT, because it's quite fragile and feels hackish, but it does work. I would assume the main blocker is that Microsoft is simply not adding support in their BIOS bootloader for GPT, which is understandable, I suppose. Is there any recourse?

    The way I see it, there are a few potential solutions:

    1. Having an alternate bootloader for the Windows kernel. NOT a chainloader. As far as I know, none exist. That's a shame.
    2. Storing as little as possible on an alternate MBR-based disk. Not liking this idea, but it's doable. I'm not sure I'd call this a solution to the problem as much as a workaround.
    3. Emulating EFI enough to get the EFI bootloader to work... I remember hearing a bit about a UEFI-on-BIOS emulator, but I can't find anything about it now. I assume this is doable, but there's probably not much demand for it yet, and it's probably no fun at all to setup. GRUB 2 seems to be able to boot a hackintosh with necessary EFI emulation, but I guess there's no interest/UEFI 2 is harder to approach (and I would assume other EFI emulators used for hackintosh are on the same boat.)
    4. Coreboot with TainoCore. Coreboot does not work on my motherboard (as far as I know,) and I'm quite sure the last effort to do this during GSoC was a failure. I'd absolutely love this solution, if it did work, though.

    Am I missing anything?


    • Related Answers
  • John Chadwick

    Well, things have changed since I first asked this question. For one, my PC is now UEFI based, so I don't have this problem anymore. Well, sort of. I had interest on pulling a similar setup on my laptop (GPT partitions, etc.) I finally managed to get a working Tianocore UEFI DUET setup, and it was about as painfully simple as it gets!

    This assumes you want all shiny, new setups. If you want to actually convert your old setup, good luck. Actually, good luck either way, as this is a spotty operation in any situation.

    A word of warning: If you're a fan of quick boot times, you may want to rethink this decision. Not that UEFI DUET is slow, but it adds another stage to your boot process, so if your BIOS/POST isn't fast, you may not like this.

    Without further adieu;

    1. You'll want a Linux setup. I used Fedora 16 off of a USB stick (with UNetBootin) and I'd highly recommend that because it practically works out of the box. You need a USB drive anyway, so don't plan on continuing without one.

    2. Grab some UEFI DUET builds. Without question, the best place to get this is here. The actual build tarballs are under the master branch of the first repository, here. Give it the old tar -xf.

    3. Setup your partitions. You should reserve 200 MB somewhere on the disk (very much preferably the beginning, and first partition.) You can format it with FAT32, but we're reformatting it later. Just make sure it shows up as a partition. You should use GPT here.

    4. Now install any additional software you may need. On the Fedora Live distribution, I found I needed yum install gdisk. I think that was it.

    5. Now go into the extracted builds directory. chmod +x ./duet-install and ./duet-install -64 -F -m /dev/sda1 (where /dev/sda1 is your desired EFI system partition.)

    6. Cross your fingers and reboot. With any luck, you'll see the TianoCore logo in just a few moments. If so, you are probably good! You'll need to setup your OS installation files on a USB drive - Tianocore does not support CD-ROM/DVD-ROM drives out of the box (and I don't know of any drivers for it.)

    You may also desire some UEFI shell binaries to play with. I found some here. Didn't test with Tianocore yet, though.

    Anyway, thanks for everyone who tried to help.

  • harrymc

    The article A BIOS to UEFI Transformation describes in detail how to use TainoCore UEFI DUET.

    I understand that you have had problems using TainoCore, but perhaps this article will work for you.

    The article does say :

    Some computers don't work with UEFI DUET. Most importantly, it's really only useful on 64-bit x86-64 computers, especially in binary form. In fact, it doesn't start up properly even on some x86-64 computers. In tests on five x86-64 systems, I managed to get one or both versions working on just three computers—a pretty dismal success rate, really. It may just be coincidence, but the two computers that worked best for me used Intel CPUs, whereas the two that worked worst and the one that worked with version 2.1 but not version 2.3 all had AMD CPUs.

    This seems to imply that one should try several versions of UEFI DUET before giving up.

    It would help to know the model of your computer.

  • Milind R

    If you even have a small spare drive, you can boot Windows(either 32 or 64 bit) from GPT on BIOS. A floppy will do.

    Boot into the Windows install/repair disc.

    Create the system drive on the small disk/floppy, and use bcdboot to put your boot files on the the newly created drive on the small disk. Add a bootsector with bootsect. Change the {bootmgr} device to boot. Boot from small disk.

    Steps are detailed here.