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I have got a new Lenovo y510p with 8.1, When I tried to install Ubuntu, It did not detect the USB. So I changed the boot mode to legacy and selected priority to legacy first. Before that I had also disabled the secure boot option.

Everything went well. But booting windows from grub wont' work and I had to change the boot every time whenever I want to use windows. So I installed boot repair and did recommended repair. It screwed everything and Ubuntu won't boot now.

So I decided to remove windows totally and start afresh

I installed Ubuntu removing windows completely creating some 10 partitions. Now When I try to install windows 8.1 it says windows can't be installed in GPT style partition. Some forums suggested that it is due to booting in legacy mode. So I changed the boot mode to UEFI. After this The BIOS won't detect my hard disk or USB stick. But the BIOS information page shows the hard disk is present. But booting won't work. It's trying to boot from network.

Please help me

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2 Answers 2

You need to install both your OSes in one mode -- either BIOS or EFI. Decide which to use and stick to it. Unfortunately, this can be tricky, since it's sometimes hard to control the boot mode. You can at least check this detail in Linux by looking for a directory called /sys/firmware/efi -- if it's present, you've booted in EFI mode, and if it's absent you've probably booted in BIOS mode. Trying to mix boot modes (BIOS for one OS, EFI for the other) can be done, but is almost always more trouble than it's worth.

Windows ties boot mode to partition table type: To install to a GPT disk, you must install in EFI mode, and to install to an MBR disk, you must install in BIOS mode.

Thus:

  1. Decide whether you want to use BIOS or EFI.
  2. Partition your disk appropriately.
  3. Install Windows, being sure to boot your installation medium in the correct boot mode.
  4. Install Ubuntu, being sure to boot your installation medium in the correct boot mode.

Do not do a cross-mode installation except as a last resort.

For more on EFI-mode Linux installations, see the following sites:

Once you know the rules and pitfalls, this isn't too hard. Unfortunately, there's a lot of flexibility, insufficient warnings in the Ubuntu installer to prevent you from making mistakes, and lots of bugs in EFI implementations that provoke making mistakes.

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Hello as a generic type answer here we go...!
Win 8 is (I believe) exclusively uefi boot and it is Windows which causes the problems. One of these problems is that it always requires the first partions on the first disk to run/load. The second problem is that it does not recognise Linux partitions and may not see extended partitions at all [that's by the by].
So you will need to load Win again, mainly if not exclusively to your first partitions. Then you will have to reload Ubuntu, possibly after reading the notes about uefi dual booting.
Feel free to completely delete this answer if my lack of actual Win 8 knowledge is too awful to view!

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Windows 8 can boot in either BIOS or EFI mode; however, computers that come with Windows 8 pre-installed almost always use EFI mode. Windows' capabilities are irrelevant for booting Linux; it's the firmware that's important for that. Windows is fine being installed to late partitions, although it can't handle being installed exclusively to logical partitions on MBR disks -- but a new computer will use GPT, not MBR, so MBR limitations are likely to be irrelevant. –  Rod Smith Apr 25 at 20:48
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