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dual boot with pre-installed windows 7 and UEFI? [Solved]
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helio
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PostPosted: Wed Aug 01, 2012 1:19 pm    Post subject: dual boot with pre-installed windows 7 and UEFI? [Solved] Reply with quote

I have a new desktop that has a windows 7 pre-installed on hard drive A (/dev/sda). There is a second hard drive B (/dev/sdb) where I tried to install a gentoo linux. The goal is to dual boot the machine into either OS. However, each time after I partitioned /dev/sdb using fdisk from a liveCD or a liveUSB, the machine could no longer boot into the pre-installed windows 7 any more. The boot manager came with the new machine is UEFI. If I deleted the partitions in /dev/sdb, the machine would boot into a recovery mode of window 7 and go through the entire recovery process.

So what was happening here? How would I install gentoo linux to this machine while keeping the pre-installed windows 7? How do I set up the dual boot under UEFI?


Last edited by helio on Mon Aug 27, 2012 1:46 pm; edited 1 time in total
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fakeCreazy
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PostPosted: Sat Aug 04, 2012 3:29 am    Post subject: Reply with quote

Have you installed gentoo on your second drive? Or you just partitioned it?
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helio
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PostPosted: Sat Aug 04, 2012 8:14 am    Post subject: Reply with quote

fakeCreazy wrote:
Have you installed gentoo on your second drive? Or you just partitioned it?


No I haven't installed gentoo on the second hard drive. It was only fdisked into 3 primary (boot, swap, extended) and 7 logical partitions (root, opt, var, usr, tmp, ......) when the aforementioned problem occurred.

Then I used gparted to re-do the partition of the 2nd HD. Now it has only 3 primary partitions (boot, swap, root). And the booting problem seems to have gone. Now the system can boot into windows 7 through UEFI by default, even with the presence of the 3 linux (msdos) partitions on the 2nd HD.

I don't understand on what has happened. But I am going to install gentoo linux on the 3 primary partitions on the 2nd HD now.
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LiamOS
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PostPosted: Sat Aug 04, 2012 10:51 am    Post subject: Reply with quote

Is Windows using /dev/sdb at all? If not, you should be able to follow the handbook up to the bootloader stage without changing how windows boots.
If you want your original partition scheme, there shouldn't really be a problem.

An alternate solution is make /boot, swap and / as small as you made them in your original scheme, do the installation and then mount and copy everything appropriately, remembering to edit /etc/fstab and such.


Also, did you set the bootable flag on /dev/sdb1 with fdisk? This may have interfered with Windows, but I have next to no experience dual booting.
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fakeCreazy
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PostPosted: Sat Aug 04, 2012 12:35 pm    Post subject: Reply with quote

helio wrote:
Now the system can boot into windows 7 through UEFI by default, even with the presence of the 3 linux (msdos) partitions on the 2nd HD.

Here you could find some tips. UEFI partitioning recommendations
Check this things:
  1. EFI does not support booting from disks with MSDOS partition table!
  2. Create new partition table and check GPT (which is required for UEFI boot).

And read your UEFI manual for the case if it has some limitations for partitioning.
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helio
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PostPosted: Sat Aug 04, 2012 3:26 pm    Post subject: Reply with quote

LiamOS wrote:
Is Windows using /dev/sdb at all?


No, /dev/sdb was initially unallocated. From Windows "my computer" the 2nd hard drive does not show up.

LiamOS wrote:
Also, did you set the bootable flag on /dev/sdb1 with fdisk? This may have interfered with Windows, but I have next to no experience dual booting.


No, I didn't set the bootable flag on /dev/sdb1 with fdisk. But the UEFI firmware seems to be able to tell any changes made to the 2nd hard drive.


Last edited by helio on Sat Aug 04, 2012 3:38 pm; edited 1 time in total
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helio
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PostPosted: Sat Aug 04, 2012 3:30 pm    Post subject: Reply with quote

fakeCreazy wrote:

Here you could find some tips. UEFI partitioning recommendations


Thanks for the link. The bios on my desktop allows me to switch between booting from UEFI and the "legacy bios" booting from disks, so I would probably choose the second option when booting from the 2nd hard drive for linux.
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helio
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PostPosted: Mon Aug 27, 2012 1:45 pm    Post subject: Reply with quote

I have been able to install gentoo linux on the second hard drive while keeping the window 7 on the first hard drive. I use the "legacy bios boot" to select which hard drive/OS to boot into without setting up a dual boot.
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nehaljwani
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PostPosted: Tue Oct 09, 2012 3:39 pm    Post subject: Reply with quote

You don't necessarily need to dual boot Windows and Linux on UEFI. Follow the guide http://www.youtube.com/watch?v=PEou2dIcMSE to convert your UEFI to MBR-BIOS without loss of data.

This guide has been made by me. Also, the referred blog will never be taken down. Although I have used it like 10 times without any loss of data, I would recommend you to backup your data before using my procedure.
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