WARNING! This is an old post and I wrote it when Ubuntu didn’t support UEFI modes very well. Please follow the steps in this post only after you exhausted all other solutions online. MAKE BACKUPS of everything, including your Windows partition. You will lose all your data !
Most newer laptops these days have UEFI enabled by default. Even though UEFI is an improvement over traditional BIOS booting methods it is still a very recent technology and has it’s own quirks and bugs. Support for UEFI on Linux is at an early stage. Installing Linux on a such a system along with Windows might not work out smoothly for everybody. This guide assumes that using UEFI and GPT is not very important to you and your only concern is to dual boot both Linux (Ubuntu) and Windows on your newly bought system. It also assumes that you are ready to delete all your partitions. Hence creating a complete backup of your data is absolutely important before proceeding. I tried these steps on an Asus laptop but it should work on most laptops with an option to disable UEFI in their BIOS settings.
- Go into BIOS and disable UEFI. Save settings and restart and go into BIOS again
- If somewhere there is a setting to delete boot options then delete all the boot options. Else skip this step. Even though I am pretty sure that you cannot delete CD/DVD from boot option but if you can then don’t do it. Save all settings and restart and go into BIOS again.
- Put your windows DVD in the optical drive.
- Somewhere (mostly on the last tab of your BIOS if it’s an Asus laptop) you will find an option for boot override. Select your DVD drive and press enter. Remember that this boot over ride option should NOT contain UEFI in it’s name.
- You will now boot from windows DVD non-UEFI mode.
- During windows installation select “custom install” and then delete all existing partitions on your harddisk. Create partition for windows. When creating this partition windows will automatically make another small partition of about 100MB size as system reserved. Leave the rest of the unallocated space for now. We will take care of that space while installing Ubuntu.
- Once windows installation is done put your Ubuntu CD in the drive and boot from it again
- During installation of Ubuntu select the option “do something else” and create a primary partition for Ubuntu.
- Now after creating partition for Ubuntu click on the rest of the unallocated space and click on create new partition again. But this time slected extended partition
- Once you create extended partition you should be able to see all your unallocated space in a sub menu under this newly created extended partition. In this unallocated space you make rest of your partitions like linux-swap (necessary for linux to work efficiently and for hibernate to work correctly) and other partitions for your data.
- Make sure that the bootloader device is sda without any partition number after it.
- Proceed with installation. If everything goes well you should be able to dual boot to both Ubuntu and Windows.
Note : If using UEFI is important to you then this guide might help - https://help.ubuntu.com/community/UEFIBooting