Info on UEFI and BIOS
computer bootup systems

(with special attention to
handling the 'secure boot' feature
when doing installs of Linux distributions)

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This UEFI and BIOS Info page

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Some UEFI/BIOS Info Sources


Around 2009, I started installing and using Linux on a home desktop computer --- and eventually on a couple more desktop computers and some netbook computers.

I have documented my Linux installs on an Ubuntu Installs web page, which links to other pages on Linux Mint installs.

In the 2009 to 2015 timeframe, I was mainly using Ubuntu 9.10 (2009 October ; 'Karmic Koala') on my main desktop and netbook computers.

Around 2016, it is about time that I will finally be changing to a newer version of Linux --- probably a version of Linux that uses the MATE desktop environment --- such as Linux Mint MATE or Ubuntu MATE.

BIOS replaced by UEFI:

Up to about 2012, computers were being sold with firmware called BIOS that controls the initialization (bootup) of the computer, until the operating system (such as Linux or Microsoft Windows) takes over.

Some developer-vendors of BIOS software/firmware include AwardBIOS, AMIBIOS, InsydeSoftware, SeaBIOS. A BIOS software system was 'firmly' pre-installed on most personal computers that were sold before about 2013.

After about 2012, the new computers that were being sold were using a new firmware bootup system called UEFI (Unified Extensible Firmware Interface).

Some developer-vendors of UEFI software/firmware include AmericanMegatrendsInc (AMI), InsydeSoftware, and PhoenixTechnologies. So depending on the computer that you buy/use, there may be a different implementation of the UEFI 'standard' on the computer.

Issues for Linux installs:

The new UEFI system was designed to make it harder for computer viruses to use the bootup system to 'take over' a person's computer. The new UEFI system required use of a 'key' code that the operating system needed to use in order to start up.

This led to some issues with how Linux 'distros' would be able to acquire a key and use the key to boot up the Linux operating system.

Over a period of several years (circa 2013-2015), various Linux 'distros' came up with methods to be compatible with the UEFI system.

However, most UEFI implementations also included a 'fall-back' method of using the old BIOS technique of booting up. This typically involved 'bringing up' the UEFI menu system at bootup (using a key like the F2 or DEL or ESC key) and turning off 'Secure Boot' mode and requesting bootup in the old BIOS mode.

Various implementations of UEFI had different menu systems. Turning off the 'Secure Boot' mode in some menus involved requesting a 'classic mode' or 'legacy mode' of booting.

A specific example:   (UEFI and Linux on an Acer netbook)

In 2013, I did a 'live' install of LMDE (Linux Mint Debian Edition) on an Acer netbook computer. I documented that 'live' install at Linux UEFI Install Notes (Preliminary) (2013).

That web page is a description of a 'live' (in-memory ; not-to-disk) install of Linux Mint Debian Edition on an Acer netbook with Windows 8 pre-installed and with the UEFI bootup system with the 'secure boot' feature.

In the 2016 timeframe, I plan to install ('to disk') a Linux distro on at least one Acer netbook with the UEFI boot system. And I will eventually install a Linux distro on a desktop computer with a UEFI boot system.

The UEFI and BIOS info on this page is intended to be available as a reference in doing those installs.

Getting ready for a Linux install
on UEFI computers:

In the years around 2013-2014, there were many articles in Linux magazines and on the internet about how UEFI worked, especially in relation to installing a Linux 'distro'.

I started reading such articles to get 'up to speed' on what may be required to install a Linux distro on a couple of Acer netbook computers that I had bought, which had a UEFI bootup system installed (along with Microsoft Windows 8).

However, most of the articles on UEFI were more puzzling than edifying. And, around 2013-2014, there were not many step-by-step descriptions of installing a Linux distro on a UEFI computer. What few descriptions I found were very 'sketchy' --- i.e. not very clear.

When I install a Linux distro (probably a Linux Mint MATE or Ubuntu MATE distro) on an Acer netbook, I plan to document how I installed the distro ('to disk') --- with details of what settings I used in the UEFI menu.

In preparation for that future Linux install, I have collected some documentation of various UEFI (and BIOS) systems --- in particular, descriptions of the options within their menu systems.


The following sections are links to local PDF files (or 'external' web pages) with BIOS/UEFI info.

When I do a 'to disk' (beyond 'live') install of Linux on a UEFI computer, I plan to document the install on this web site. At that time, I may return to this page to update it.

UEFI info:

BIOS-only info:

The following Linux startup stages run,
after the BIOS or UEFI firmware runs.

Knoppix Boot Sequence

(On Linux systems after about 2007,
LILO was usually replaced by GRUB or GRUB 2.

After 2015, many Linuxes use systemd as the 'init' process.)

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Page was created 2015 Sep 11.

Page was changed 2015 Sep 22.
(Added a few more UEFI links.)

Page was changed 2015 Nov 02.
(Added 2 images.)

Page was changed 2019 Jan 07.
(Added css and javascript to try to handle text-size for smartphones, esp. in portrait orientation.)