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Thread: UEFI and additional partitions

  1. #1
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    UEFI and additional partitions

    As I understand it, UEFI (which I have on my machine) enables you to have more than four primary partitions. Are there any Ubuntu partitioning tools that enable one to take advantage of that? gparted doesn't seem to be able to do it.

  2. #2
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    Re: UEFI and additional partitions

    No, UEFI has nothing to do with the number of partitions, as far as I know.

    It's the partition table type on the disk that controls that. The older type MBR (or MSDOS) table has the limitation of 4 primary partitions, or 3 primary and 1 extended holding more logical partitions.

    The GPT table allows many partitions, there is no difference between primary and logical.

    Windows 7 can use UEFI only with gpt table so someone might think the option to have more than 4 partitions is because UEFI, when in reality it's because of gpt.

    Ubuntu does support gpt long time ago and you can have your disk with gpt table. But if you dual boot on the same disk, you have to use UEFI and win7 because of the mentioned limitation that it needs the combination of gpt+uefi to work.
    Darko.
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  3. #3
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    Re: UEFI and additional partitions

    Quote Originally Posted by pwabrahams View Post
    gparted doesn't seem to be able to do it.
    darkod has clarified the difference between UEFI and GPT. Gparted can both create a GUID partition table (GPT) and can create more than 4 partitions in a GPT drive.
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  4. #4
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    Converting MBR to GPT?

    Well, right now my system is dual-booting into Windows 7 and Kubuntu 12.04. It has MBR-type partitioning,and the BIOS tells me that it's UEFI-capable. Is there a way to convert it from MBR to GPT? Or do I have to throw everything out (or copy it all to an external drive) and start over?

    I suppose that if I do manage to do the conversion, I then have to figure out how to inform Windows 7 and Kubuntu where everything is, since the partition IDs will probably change.

    I wish I had known about all this when I still had a factory-fresh machine.

  5. #5
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    Re: UEFI and additional partitions

    I don't think you can convert it. You need to make a full backup of all your personal data from both OSs, and do clean installs.

    Before starting the install, make sure you change to UEFI mode in bios, and to make a gpt table on the disk. Then install win7.

    When installing ubuntu, make sure to boot the cd in UEFI mode (there will be an option for that in boot devices) so that it installs in UEFI mode. If you don't do that, the dual boot won't work.
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  6. #6
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    Reinstalling Windows 7?

    Switching to gpt sounds like a hopeless task, because I have no way of reinstalling Windows 7. I'm afraid that if I tinker with it at all, it will fail the genuineness tests.

    If anyone comes up with a way of converting a system with Windows 7 preinstalled (like most computers sold these days) to gpt with Linux in one partition, I'd love to hear about it.
    Last edited by pwabrahams; October 8th, 2012 at 03:29 AM.

  7. #7
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    Re: UEFI and additional partitions

    I have not idea if this works or not. First you have to have some space between MBR sectors for gdisk to let you convert from MBR to GPT. And you have to create the extra efi partition at the beginning of the drive and the Windows MSR near the start of the drive. Usually moving partitions around to allow for all that is not easy. And I do not know for sure where the Windows efi boot files are to copy, should be somewhere on a Windows install DVD set, but most Windows are pre-installed and will not have those files.

    Of course full backups are absolutely required before even attempting something like this.

    Windows Recommended UEFI-Based Disk-Partition Configurations
    http://technet.microsoft.com/en-us/l...8WS.10%29.aspx
    Change the booting style of Windows Vista or 7 x86_64 versions from BIOS-MBR mode to UEFI-GPT mode without formatting or reinstalling
    https://gitorious.org/tianocore_uefi...4_BIOS_to_UEFI
    Windows installs the efi bootloader to (ESP)/EFI/Microsoft/Boot/ which is identical to (WINDOWS_SYSTEM_PART)/boot/microsoft/ incase of BIOS systems.
    The dir mainly consists of bootmgfw.efi, bootmgr.efi, memtest.efi and 'bcd'.
    Post #76
    http://ubuntuforums.org/showthread.php?t=1719851&page=8
    efi\Microsoft\Boot\bootmgfw.efi
    For more info on UEFI boot install & repair - Updated Oct 2015:
    http://ubuntuforums.org/showthread.php?t=2147295
    Please use Thread Tools above first post to change to [Solved] when/if answered completely.







  8. #8
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    Preinstalled Windows 7

    The fact that I have Windows 7 preinstalled makes disruptions risky. For instance, I could move the boot partition (sda1) with gparted, but that might cause the machine not to boot, or at least not to boot into Win7. Those Microsoft articles seem oriented towards the case where you're starting with an empty disk.

  9. #9
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    Re: UEFI and additional partitions

    I strongly advise against moving any existing partitions.

  10. #10
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    Partitions moved successfully

    The machine came with four primary partitions -- a difficult situation for installing Linux. I ended up preserving #1 and #4, with #2 still a Windows primary and #3 an extended partition that in turn contained the original #3 (as a logical) and 3 logicals for Kubuntu. And that has seemed to work. But if Lenovo had taken full advantage of UEFI, things would have been easier and cleaner.

    I figured I should leave #1 and #4 alone since #1 is the boot partition and #4 is the recovery partition. Of course, there's now no way I can recover Windows without going back to the factory configuration, and even that might not possible any more. So preserving #4 might actually be pointless.

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