Boot managers and boot devices on a PC with UEFI firmware

UEFI firmware technology may have its positive aspects, but it also comes, like everything else, with its not-so positive aspects. It is not-so positive because it was a pain to figure out exactly how it works with OS boot managers and boot devices, especially when attempting to dual-boot multiple OSs on one hard drive, or even on multiple hard drives.

Instead of installing the boot files in the Master Boot Record (MBR), an entry for each OS in created in /boot/efi/EFI directory, which should be in an EFI partition. That results in a corresponding entry for each OS in the boot menu.

For example, take the entries in this screenshot, which was taken from the boot menu of a test PC, a custom-built box with an ASRock motherboard. Each OS entry represents a different installation of the OS, and not necessarily on the same hard drive. You can tell that I’ve installed Fedora a lot more times on the PC than other OSs. The AHCI P2: WDC WD5000… entry is for a 500 GB hard drive, while the ASUS… entries are for an external CD/DVD drive.
UEFI boot managers

In this screenshot, the Ut165… entries are for a 4 GB Flash stick used for installing the Linux distributions. The AHCI P3: WDC WD3200… entry is for a 320 GB hard drive.
Windows UEFI boot managers

One thing that I’ve learned about installing an OS on a PC with UEFI firmware is this. The system will not boot if the entry for the hard drive is chosen as the boot device. And that is true whether it is selected as the boot device from the boot menu, or is made the default boot device in the UEFI setup utility. In this screenshot, for example, Ubuntu 14.10 and Windows 7 are installed in dual-boot fashion on a 500 GB hard drive, which is represented by the AHCI P3: WDC WD5000… entry. The system will not boot if the AHCI P3: WDC WD5000… entry is chosen as the boot device. To boot, an entry for any of the installed OSs must be selected from the boot menu or made the default boot device.
UEFI boot managers

Knowing that UEFI is handled differently by each PC vendor, the foregoing might not even be true if your PC is not built using an ASRock motherboard, like a reader indicated in this forum post.

Related Posts

Want to stop creepy online tracking? Help the EFF test Privacy Badger Privacy Badger is a new tool from the Electronic Frontier Foundation designed to stop creepy online tracking. It's an extension for Firefox and Ch...
FXPAL open source’s DisplayCast DisplayCast is a screencast and sharing application designed for intranets. It is developed by FXPAL (FX Palo Alto Laboratory). DisplayCast include...
Scaling Jenkins using DCOS and Marathon Today, we’re excited to share some of the work we’ve done to reliably deploy Jenkins masters using Mesosphere’s Datacenter Operating System (DCOS) and...
The latest on GNOME Software from Fedora Rawhide GNOME Software is the built-in software management application on GNOME 3. It is a beautiful application. In the future, it might be all you need t...
Plasma Media Center 1.1 and digiKam 3.3 Plasma Media Center 1.1 was released today August 20, while digiKam 3.3 was released on August 6. Plasma Media Center is a promising media center appl...
Flatcar: A tool for creating Docker-ready Rails projects One of the most compelling reasons to use Ruby on Rails is the ease in which you can get a web project up and running. And one of Docker's key benefit...

We Recommend These Vendors and Free Offers

ContainerizeThis 2016 is a free, 2-day conference for all things containers and big data. Featured, will be presentations and free, hands-on workshops. Learn more at

Launch an SSD VPS in Europe, USA, Asia & Australia on Vultr's KVM-based Cloud platform starting at $5:00/month (15 GB SSD, 768 MB of RAM).

Deploy an SSD Cloud server in 55 seconds on DigitalOcean. Built for developers and starting at $5:00/month (20 GB SSD, 512 MB of RAM).

Want to become an expert ethical hacker and penetration tester? Request your free video training course of Online Penetration Testing and Ethical Hacking

Whether you're new to Linux or are a Linux guru, you can learn a lot more about the Linux kernel by requesting your free ebook of Linux Kernel In A Nutshell.

Leave a Comment

Your email address will not be published. Required fields are marked *