Let me preface this by saying that I have no Linux experience at all; I really want to learn, but this is my first exposure.

Trying to dual boot Ubuntu 14.04 on my Asus K55a laptop. The laptop came preinstalled with Windows 8. I did a clean install of Win7. This install was in legacy bios, not UEFI. I tried to install Ubuntu 12.04 off a flash drive but the installation did not detect an existing OS, just one huge unallocated partition. When I checked the flash drive from the bios settings it was identified a UEFI drive. I assumed that the trouble I was having was because Win7 was a legacy bios install and Ubuntu was trying to install as UEFI.

I tried to start from scratch. I made a UEFI Win7 flash drive, installed from that. Tried to install Ubuntu 14.04 from a UEFI flash drive, encountered the same problem. I did some searching and found a thread with a similar problem on the Ubuntu forums with the following instructions for making the Windows system visible:

Open Terminal and type the following:

sudo dd if=/dev/sda of=sda.mbr bs=512 count=1

To clear the GPT signatures you'll need gdisk by typing: sudo apt-get install gdisk

sudo gdisk /dev/sda

Switch to expert mode: x

To "Zap" GPT enter: z

The selection for the first question Y and answer N for MBR!!

I followed these instructions and I think it erased my Win7 install/partition, because if the Ubuntu flash drive wasn't in when I tried to boot up it would only boot into the bios menu. It gave me some warning about "No bootable device."

1) What is the problem with Ubuntu not recognizing the existing OS? 2) Did I erase my Win7 installation/partition when I followed those instructions above? 3) Can I resolve this issue if I've already reinstalled Win7, or will it require starting from scratch? 4) How do I fix this?

  • When you installed Windows in BIOS mode, that is when you have to clear the left over backup gpt partition table. Windows does not correctly convert from gpt to MBR. Better to use fixparts. And if Windows is in UEFI boot mode you must have gpt partitioning. Best which ever boot mode you really want that both are installed in either UEFI or both in BIOS. And with UEFI you need gpt or with BIOS you must have MBR(msdos) partitioning. You may be able to restore gpt with fixparts or gdisk. rodsbooks.com/fixparts And: rodsbooks.com/gdisk/repairing.html
    – oldfred
    May 23 '14 at 17:02


There is a wealth of information in this forum. Also there no one set of instructions that will help guilde you through the installation process.

Here are few good links that I followed that helped me in the process.

  1. Dual-boot Windows 8 and Ubuntu 12.10 in UEFI mode
  2. Install Ubuntu Linux Alongside Windows 8 in 10 easy steps
  3. Installing Ubuntu on a Pre-Installed Windows 8 (64-bit) System (UEFI Supported)

BTW after significant effort I was able to dual boot Ubuntu 12.04 along side Window 8.1 thank to this community. Also I almost never boot to the Window 8 partition.

Welcome and good luck

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