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?
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.
On the other hand after I tried everything to enter the UEFI setup utility on a different computer and failed, sudo systemctl reboot --firmware-setup rebooted me straight into UEFI and the "Exit without saving" option exited without making any changes to my UEFI settings. Otherwise I would have been unable to enter the UEFI, select the Boot tab, select the "Boot priority" option, and select the USB flash drive that contains my Ubuntu installation media as my first boot device on this computer.
Booting from a live USB environment and choosing to install Ubuntu is a standard method for reinstalling your system. Reinstalling Ubuntu is considered a last resort if other troubleshooting steps for issues like black screens do not work. The process typically involves booting from the Ubuntu installer USB.
Before reinstalling Ubuntu it is always recommended to back up your important data using the live USB environment option of the Ubuntu installer USB.
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".
On Ubuntu 20.04 opening a terminal and running
sudo systemctl reboot --firmware-setup
worked for me and rebooted me into the UEFI/BIOS.
