I have a HP Elite book 840G3 laptop with Windows installed in the primary drive and Ubuntu installed in the second drive. What is to be done to get to pick the operating system option on starting up.
Right now I press Esc on startup and pick the needed drive from the BIOS Boot Menu screen.
You need to install Ubuntu in UEFI mode (basically creating an EFI parition during installation.)/
Legacy vs UEFI
Legacy (x86 bit) - if you install Ubuntu with
Root
Swap
then the Ubuntu OS will be installed in Legacy Mode (meaning it won't support UEFI like Windows (x64bit).
UEFI - If you install Ubuntu with following paritions
Root
Swap
EFI
on your PC/Laptop then the Os is installed in UEFI Mode. Usually devices that came into market post 2010 are UEFI Supported meaning x64bit.
Once you've installed Ubuntu in UEFI mode then during boot you will see Grub which also lists Windows bootloader.
Please visit - https://help.ubuntu.com/community/UEFI to learn and install Ubuntu in UEFI mode.
I've installed Windows 7 Ultimate - Ubuntu 16.04 LTS (x64) in dual-boot. While installing Ubuntu, the installer recommended Legacy mode instead of UEFI, because of something with Win7. At the first reboot, the Windows 7 option was missing from the GRUB Menu. All I had to do was running "sudo update-grub" command from a terminal in Ubuntu. At the next reboot, the Windows 7 option appeared in the GRUB Menu, and I was able to boot Win7 without any problem. That's why I love Ubuntu! Hope this helps others!
