95 votes
Accepted

Is there a way to get the BIOS version from inside Linux?

Without superuser privileges It is as simple as reading the following file: $ cat /sys/class/dmi/id/bios_version 1.1.3 With superuser privileges Use dmidecode: $ sudo dmidecode -s bios-version 1....
cuonglm's user avatar
  • 154k
48 votes
Accepted

How to create a bootable Debian USB drive using Windows

To create a bootable USB, you can follow the steps below: STEP 1 Go to the website of the OS you wish to install, and find an iso image to download. In your case, since you want to run a Debian OS, ...
assefamaru's user avatar
26 votes

Unmount /boot after booting

In theory neither /boot/ nor /boot/efi are commonly used after boot. The two form a bridge between the BIOS (or similar) and the operating system. They are not generally used at runtime. They are ...
Philip Couling's user avatar
23 votes

Laptop boots directly to Ubuntu, can't access BIOS or Boot menu anymore

It sounds like you enabled the "fast boot" option in your BIOS setup which disables the F2 setup and F12 boot menu prompts. Power-off your laptop and hold down the F2 key, then power it on for the ...
Toushin Taishi's user avatar
22 votes
Accepted

Is /dev/nvram dangerous to write to?

I'm curious as to exactly why you'd want to run such a command if you think it might damage your computer... /dev/nvram provides access to the non-volatile memory in the real-time clock on PCs and ...
Stephen Kitt's user avatar
17 votes

How does the grub efi loader find the correct grub.cfg and boot directory?

After using ghex to examine my "BOOTX64.EFI" file in the efi partition I found this line. search.fs_uuid a43d1f11-6ebe-477d-8be3-321a33bc37f9 root hd2,gpt4 set prefix=($root)'/boot/grub' This shows ...
Joe's user avatar
  • 1,316
16 votes

Laptop boots directly to Ubuntu, can't access BIOS or Boot menu anymore

If your OS uses systemctl, you can bypass "fast boot" via the command line: sudo systemctl reboot --firmware-setup This should reboot you directly into the BIOS setup menu.
Lord Elrond's user avatar
16 votes

Unable to shutdown Windows after installing GRUB

This issue is faced by many users using dual boot win10/linux. GRUB seems to have some incompatibility with windows 10 fast boot process. Win 10 default shutdown does not actually shut down the whole ...
danish's user avatar
  • 261
16 votes

Unmount /boot after booting

Side effects : None that I have ever noticed myself. Apart of course from the burden brought by the necessity to be certain to have it mounted prior to installing a new kernel. (be certain because in ...
MC68020's user avatar
  • 7,981
15 votes

Is /dev/nvram dangerous to write to?

It probably could but it depends on your BIOS. See this related problem with EFI configuration where a laptop was bricked by clearing EFI variables. If some BIOS can't handle cleared variables, it's ...
Olivier's user avatar
  • 615
15 votes
Accepted

Is there an open source software to simulate and virtually program a computer BIOS?

There are several virtual machine emulators that can emulate an x86 processor and peripherals. Each comes with a BIOS, several of them with an open-source BIOS. You should look at QEMU, which operates ...
Gilles 'SO- stop being evil''s user avatar
13 votes

BIOS / GPT: do we need a 'boot' flag?

grub itself does not care about boot flags. An EFI System partition is distinguished by its GUID type C12A7328-F81F-11D2-BA4B-00A0C93EC93B, not by a boot flag. Yes, this partition needs to be ...
AlexP's user avatar
  • 10.5k
11 votes

Is /dev/nvram dangerous to write to?

It would probably be fixable either because the firmware will notice it fails checksum and reset it (on the next boot), or alternatively by pulling the CMOS battery and/or using a CMOS clear jumper. ...
derobert's user avatar
  • 110k
11 votes

Can't boot to windows after installing Ubuntu in UEFI

Depending on exactly what the warnings said, and what exact choices you made when installing Ubuntu, the installation process may have done one of a few things: It may have converted the partitioning ...
telcoM's user avatar
  • 96.9k
10 votes
Accepted

Total runtime of machine

This isn’t something the firmware tracks, as far as I’m aware. Even BMCs don’t measure total uptime. This won’t help with past uptime from previous boots, but you can start recording uptimes now, by ...
Stephen Kitt's user avatar
10 votes

kworker thread kacpid_notify/kacpid hogging 60-70% of CPU

The information provided by others is largely correct, but the solutions are not. The tricky bit will be finding the rogue interrupt, as it will vary depending the hardware you have, and may also ...
ladar's user avatar
  • 226
10 votes
Accepted

What is the point of the kernel reserving CONFIG_X86_RESERVE_LOW memory for the BIOS?

You should see a longer help text for this config option. It offers two reasons. config X86_RESERVE_LOW int "Amount of low memory, in kilobytes, to reserve for the BIOS" default 64 range 4 ...
sourcejedi's user avatar
  • 50.3k
9 votes

Is there a way to get the BIOS version from inside Linux?

You can use lshw , hwinfo , inxi and hardinfo (DMI): # lshw -class memory # hwinfo --bios $ inxi -M $ hardinfo The above command should work after installing them through your package manager. Only ...
GAD3R's user avatar
  • 66.8k
9 votes

Unmount /boot after booting

Now that I think about it, you are asking this from the specific point of view of a bastion virtual machine. These typically are stateless with very little installed. If you are remotely concerned ...
Philip Couling's user avatar
6 votes
Accepted

[Firmware Bug]: the BIOS has corrupted hw-PMU resources and CentOS 7 not initializing

Something caused a memory corruption, which was propagated to the root filesystem (to its journal, to be precise). So XFS shutdown itself down. To correct the issue, boot from a live CentOS disk and ...
shodanshok's user avatar
6 votes

Automatic start-up when electricity goes on?

This is usually done in the BIOS under power settings. It may be under South Bridge / Chipset. in AMI it says 'Restore AC power loss' and you can choose "power Off" which is default, or "Power On" or ...
Daniel Near's user avatar
6 votes
Accepted

Does the Linux Kernel access HW through BIOS, or does it directly interface with the HW?

It depends. In most cases, the kernel drives hardware directly, without going through the system firmware; but it does rely on firmware-provided functions in some cases (e.g. through ACPI). The ...
Stephen Kitt's user avatar
6 votes
Accepted

Unmount /boot after booting

Testing this, no problems seem to appear; can it have any side effects I'm missing? No, not really, except that some tools may actually need it mounted that you may have not thought of (for example, ...
Austin Hemmelgarn's user avatar
5 votes
Accepted

how to create a bootable flash that can boot as both BIOS and UEFI?

After a lot of research, I found https://debian-administration.org/users/dkg/weblog/112: Copy/pasting here for longevity, all credit goes to the original author. (I modifed the steps a little so the ...
OneOfOne's user avatar
  • 1,394
5 votes

Hyperthreading: is there a way to know from the command line if it is enabled in BIOS?

util-linux's lscpu shows whether hyper-threading is enabled (or anything similar): $ lscpu [...] Thread(s) per core: 2 [...] 2 or more in the "Thread(s) per core" line means hyper-threading is ...
Stephen Kitt's user avatar
5 votes
Accepted

How does the Linux kernel retrieve ACPI tables from the system firmware?

Please see: http://wiki.osdev.org/RSDP The first step in retrieving the ACPI tables is finding the Root System Description Pointer, or RSDP. On UEFI systems, it is conveniently given within the ...
telcoM's user avatar
  • 96.9k
5 votes

Is there a way to get the BIOS version from inside Linux?

I was wandering in /sys folder then I went into /sys/firmware/dmi/tables then got two files DMI and smbios_entry_point. If you read DMI file then in my case first word was LENOVO and second word was ...
Prvt_Yadav's user avatar
  • 5,872
5 votes
Accepted

GRUB disappeared from Boot Menu after UEFI (BIOS) upgrade on Thinkpad X1 Carbon gen5

Your UEFI upgrade has probably reset the NVRAM settings, which on UEFI systems also include the boot configuration for installed operating systems. Not all the boot menu items are detected on-the-fly ...
telcoM's user avatar
  • 96.9k
5 votes
Accepted

Multiple Linux distros break BIOS fan control?

Please check the BIOS setting before installing Linux. The common BIOS optiona for Linux installation is to enable CSM support and select UEFI and legacy support option in the boot device control. ...
Sivamani V's user avatar
5 votes
Accepted

kworker thread kacpid_notify/kacpid hogging 60-70% of CPU

I've been researching on this problem also. I've tried changing the BIOS settings and all kinds of tweaks. I finally came across this link (https://forum.manjaro.org/t/kworker-kacpid-cpu-100/131532) ...
Jim C's user avatar
  • 74

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