Recently installed Ubuntu 14.04 along with windows 8.1 in my dell inspiron 15 5547 (Legacy Mode, windows 8.1 in uefi mode), while restarting OS selection window is not displayed. Every time I need to login to BOOT Manager to login to Ubuntu. Help me, TIA

  • What options does this boot manager give you? – s3lph May 17 '15 at 19:25

You wrote:

Recently installed Ubuntu 14.04 along with windows 8.1 in my dell inspiron 15 5547 (Legacy Mode, windows 8.1 in uefi mode)

Your parenthetical comment reveals the cause of the problem. Mixing BIOS/CSM/legacy mode and EFI/UEFI mode is a Bad Idea. On most computers, doing so makes it difficult to switch boot modes.

Fortunately, the solution is not too difficult: Install an EFI boot loader for Linux. Several are available (see the preceding link), but two are likely to be easiest to install and maintain:

  • rEFInd -- Download and prepare a USB or CD-R image of my rEFInd and boot with it. It should detect both Windows and Ubuntu. Test booting both OSes. If both work, boot to Ubuntu and install the PPA or Debian package version of rEFInd. It will then take over as your default boot manager, and you'll be set.
  • EFI-mode GRUB -- GRUB is Ubuntu's default boot manager, but you've got the BIOS/CSM/legacy version installed. You must replace this with the EFI-mode version. This is most easily done by booting an emergency disc to EFI mode and running Boot Repair (in the boot-repair package, IIRC). The trick is booting to EFI mode. You may need to use rEFInd (as above), or you can disable BIOS/CSM/legacy support in your firmware and boot your Ubuntu installation disc to its "try before installing" mode, or you might be able to use your built-in boot manager to boot the installer to EFI mode.

The biggest problem you face is variability from one EFI to another. This variability means that there is no standardized way to get to the firmware's built-in boot manager, force an EFI-mode boot, and so on. There are also bugs that can interfere with one or both of these solutions. You'll just have to take these issues one at a time as you work toward a solution.

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