Linux boot uefi bios

Official Ubuntu Server compressed image boots in UEFI and BIOS mode

When you have installed these systems from a compressed image file, and you reboot, you log in with the following user and password:

user: ubuntu

password: ubuntu (and you are prompted to change it directly after the first login)

Preparation

It might help to prepare by reading the following link

The following link gives more background information about partitioning

Original attempt

Not stable enough to survive certain updates

I expected that it could be installed into a USB pendrive as a good alternative to a persistent live system, possible to update and upgrade without limits. But unfortunately a current update involving a new kernel and updating grub will make it fail to boot. So this system is not stable enough to survive certain updates. It is good only as an illustration of a method to make a bootable drive in UEFI as well as BIOS mode.

Stable alternatives

If you want a stable portable system, that boots in UEFI mode as well as BIOS/CSM mode, and in 64-bit as well as 32-bit computers, you can try One pendrive for all PC (Intel/AMD) computers. If you want a pendrive with a live and an installed system, you can try A new and so far successful attempt to create a stable portable system, that works in UEFI and BIOS mode.

Detailed instructions

Stable alternative 1

There are links to instructions how to make an installed system (typically in a USB pendrive) that works with UEFI and BIOS, and is small enough to work in an undersized 16 GB pendrive. This system is created from Ubuntu 16.04 LTS ‘Xenial’ amd64 (‘gamma’ because it is beyond beta), and was simplified compared to the previous methods to make a stable installed system for UEFI and BIOS mode.

This link shows the post in an Ubuntu Forums tutorial, where the method was published:

with a description how to make it ‘from scratch’ plus a link to uploaded compressed image files plus a small script to fix the GPT after cloning.

Stable alternative 2

See this link to the sub-page: /stable-alternative-18.04.1

Installation from a compressed image file

• if you want to learn how to do it, or
• if you want to be sure of the content (and don’t rely on me), or
• if you want hibernation, or
• if you want an encrypted disk (LVM with LUKS encryption),

then you must do it yourself. (In the encrypted disk case, you must create the passphrase yourself during the installation.)

Compressed image file

It is straight-forward to install from a compressed image file using mkusb or mkusb-nox. Some tools may not work with compressed images of such large files. I tried in Lubuntu Xenial 32-bit daily to restore disk image with gnome-disks alias Disks, but it considered the size to be 3.5 GB, when it was 12 GB, so the image was truncated, Bug #1571255

After this cloning operation you should run gpt-fix in order to match the gpt data to the current drive size.

Description of the short-cut to make an installed system (typically in a USB pendrive) that works with UEFI and BIOS from a compressed image file:

Download source 1

Download the following compressed image files from

where you also find a gpg-signed file with md5sums, md5sum.txt.asc.

Remember to check with md5sum, that the download of the compressed image file was successful.

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How do I enter the BIOS/UEFI from Ubuntu?

Windows 10 has a feature to enter BIOS/UEFI directly from the OS, which is handy for machines that do not allow you to enter them during startup. I would like to install Ubuntu on an OEM device and obviously I will be using the Windows feature to do this, but I will still require BIOS access in the future. How can I access the BIOS from Ubuntu?

Related: askubuntu.com/questions/318796/… Also can we get make and model # of this machine that doesn’t allow BIOS access at boot time?

sudo systemctl reboot —firmware-setup but this is not available on all systems. I hope I understood your question right.

2 Answers 2

The BIOS/UEFI can be accessed by pressing the appropriate key at boot time. A table of BIOS/UEFI access keys for different motherboard manufacturers is in this answer.

You can also enter the BIOS/UEFI directly from Ubuntu the way you can do sometimes from Windows by running sudo systemctl reboot —firmware-setup but I strongly recommend that Ubuntu users shouldn’t use this method except for when all other methods of accessing the UEFI settings have failed. When I tried this command it reset the CMOS and all my UEFI settings got reset back to their default values including the clock. When I exited from the UEFI settings to reboot, the screen froze and I had to manually power off the computer and cold start it. Fortunately I knew my previous UEFI settings, so I could immediately restore them before exiting from the UEFI settings.

This is what man systemctl has to say about the —firmware-setup option.

--firmware-setup When used with the reboot command, indicate to the system's firmware to reboot into the firmware setup interface. Note that this functionality is not available on all systems. 

man systemctl didn’t say anything about resetting the CMOS. It only said «this functionality is not available on all systems».

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