Convert legacy/BIOS Windows to UEFI Windows for dualbooting

If you machine supports UEFI, but your current install of Windows is in legacy mode (you can check by following our dualboot notes in the directions) you may not need to reinstall Windows in order to dualboot.


CREDIT WHERE IT'S DUE: Two users combined their brains to discovery this works. Read the original thread here.


 This article talks about converting a legacy set up to UEFI. Your machine still needs to support UEFI booting for this to work, and even then there *could* be complications so be careful trying this. However, at least 1 case confirmed this working, so we think it could help users avoid reinstalling Windows in order to dualboot.
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  • Avatar
    Trương Bá Việt Nhân

    Are there any help? Could Cloudready get installation on PC with BIOS (none-UEFI) system based?

  • Avatar
    Dinh Hoang

    Same question with Truong Ba Viet Nhan. I have an old laptop with legacy mode, windows 7 and want to dual boot Cloudready. Are there any guides for manual steps?

  • Avatar
    Forrest Smith

    There is no way to use our pre-built dualboot installer if your machine only supports legacy BIOS. You have to have a machine that at least is *capable* of UEFI booting.

    If you want to dualboot on a Legacy-only machine, it is definitely possible but will require you to manage the process of installing and configuring grub or Windows boot manager to let you choose between the two at boot. You'd probably need to install CloudReady first, and then resize the storage and install Windows second.

    Unfortunately, we don't have a way to help or guide you through this.

  • Avatar
    Chas Belfield

    That's a shame, I have a Lenovo S10-3 that I have Lubuntu 16.04 installed on and would have loved to dual boot with cloud ready, but unfortunately it is not UEFI capable.

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    Below how i did it:
    1) Create USB drive with cloudready
    2) Install on the second usb drive Gparted live
    3) Boot from second drive (Gparted live).
    4) Create two partition with gparted: first ext4 (min 4GB) and second ext2 (min 2 GB)
    5) Copy partition ROOT-A from CloudReady usb drive to created ext2 partiton
    6) Copy partition STATS from CloudReady usb drive to created ext4 partiton
    7) Mount new ext2 partiotion with gparted live.
    8) Edit file /sbin/chromeos_startup. You need find where set variable STATE_DEV. And change it to you new ext4 partiton. (for example STATE_DEV=/dev/sda7)
    9) Install GRUB4DOS in Windows and add record for chromeOS:
    title ChromiumOS
    insmod ext2
    set root=(hd0,5)
    kernel (hd0,5)/boot/vmlinuz root=/dev/sda6 rw noresume noswap i915.modeset=1 loglevel=1 cros_debug quiet

    Change (hd0,5) to you created ext2 partition number.

  • Avatar
    Forrest Smith

    Hi Anton!

    Very cool! I haven't seen any approach like this before.

    Note that updates won't work in this configuration, since CloudReady uses a double-buffered update system and relies on both ROOT/KERNEL-A and ROOT/KERNEL-B (alternately) to allow for background install of updates.

    I'm not certain as to how that switch back and forth is specified so I don't think I can coach you through recreating that, but hopefully this tip can give you a starting point.

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