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Old 07-28-2022, 06:01 AM   #1
stoorky
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Can BIOS changes be applied without having to reboot?


I was looking for a way to disable my webcam. I'm using Debian 11 / Gnome 3.38. I looked into Gnome's privacy settings, but they only apply to snaps, flatpaks, and so on (see https://gitlab.gnome.org/GNOME/gnome...e_requests/851)

My BIOS has an option to enable/disable the webcam, so I managed to do it with # smbios-token-ctl. It works just fine, but I have to reboot my laptop each time I change this setting (e.g., my webcam keeps working even though I just disabled it with # smbios-token-ctl, until the next reboot).

Having to reboot defeats my purpose, I wanted a quick way to easily enable/disable the webcam.

Is there any way to force Linux to take the BIOS change into consideration without having to reboot ?

Last edited by stoorky; 07-29-2022 at 08:40 AM.
 
Old 07-28-2022, 06:53 AM   #2
syg00
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Must have been the best part of a decade ago, but I went to a LCA conference that had, amongst its schwag, a little stick-on webcam slide cover. Simple but effective.
Maybe something like that might suffice.
 
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Old 07-28-2022, 11:16 AM   #3
boughtonp
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A physical cover only handles video, not audio - though presumably muting/disabling microphone can be done via volume control.


In any case, the thread title should be updated to mention the actual aim - disabling webcam without reboot - because it's entirely possible people can answer that without having a clue what smbios-token-ctl is, but are not bothering to look at the thread due to not having a clue what that is.

 
Old 07-29-2022, 08:46 AM   #4
stoorky
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Quote:
Originally Posted by boughtonp View Post
In any case, the thread title should be updated to mention the actual aim - disabling webcam without reboot - because it's entirely possible people can answer that without having a clue what smbios-token-ctl is, but are not bothering to look at the thread due to not having a clue what that is.
I changed the title, but not about the webcam. I am actually more interested if someone knows if BIOS changes can be applied without having to reboot. For the sake of knowledge.
 
Old 07-29-2022, 11:59 AM   #5
lvm_
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No, it doesn't work this way. But you can disable the camera device - google for 'disable /dev/video0'.
 
Old 07-29-2022, 12:25 PM   #6
!!!
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Googling found this interesting piece of Hardware: https://www.tomshardware.com/news/li...out-rebooting-

Without that, it seems pretty certain that you would have to reboot, based on the concepts of how a BIOS works with an OS.

But after reading this, I would not bet a lot on it being impossible:
https://superuser.com/questions/1148...from-linux-cli

An interesting experimentation Journey, the results of which would likely vary depending on the particular BIOS/UEFI model.

Last edited by !!!; 07-29-2022 at 12:42 PM.
 
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Old 07-29-2022, 03:25 PM   #7
sundialsvcs
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I've got a little adhesive star-shaped sticker on my laptop which neatly covers up the camera.
 
Old 08-01-2022, 10:07 AM   #8
David Roesch
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Quote:
Originally Posted by stoorky View Post
Is there any way to force Linux to take the BIOS change into consideration without having to reboot ?
Most if not all of the BIOS' instructions are read by the computer at initial boot time, before the computer is even aware of what OS it will boot in to.
Given that, I doubt that there is a way to "backfeed" permanent instructions to the BIOS from any OS once that OS has booted.
 
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Old 08-01-2022, 03:30 PM   #9
jefro
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I don't think your command is changing bios. It is blacklisting. You can reboot once to change bios settings and they should maintain.

Otherwise blacklist on boot by OS.
 
Old 08-01-2022, 03:42 PM   #10
rtmistler
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Quote:
Originally Posted by stoorky View Post
Having to reboot defeats my purpose, I wanted a quick way to easily enable/disable the webcam.
I realize you've moved towards the BIOS question, but personally I use electrical tape. It is jet black to make it completely opaque, and it's not Gorilla tape where it leaves residue on the PC. Of course this area has somewhat been considered. My built in webcam is at the bottom of the screen near my laptop's keyboard, so if I use it and type, my knuckles appear like giant spider legs taking over the screen. So I taped that over and bought a USB one which (a) can be unplugged and (b) came with a privacy door to cover it.
Quote:
Originally Posted by stoorky View Post
Is there any way to force Linux to take the BIOS change into consideration without having to reboot ?
This is not about Linux, it's your computer. And "no" I've never seen this practice allowed.
 
Old 08-02-2022, 01:52 PM   #11
stoorky
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Quote:
Originally Posted by jefro View Post
I don't think your command is changing bios. It is blacklisting. You can reboot once to change bios settings and they should maintain.
.
NOPE !
smbios-token-ctl is a command to modify the BIOS's settings. It has nothing to do with blacklisting.

My BIOS has a setting to enable or disable the camera. I definitely can do it from within Linux, then reboot, go into the BIOS, and check that indeed it has been changed.

Code:
# smbios-token-ctl | grep Camera
  Token: 0x0285 - Camera (Enable)
   Desc: To enable Camera
  Token: 0x0286 - Camera (Disable)
   Desc: To disable Camera

# smbios-token-ctl -i 0x0285
================================================================================
  Token: 0x0285 - Camera (Enable)
  value: bool = true
   Desc: To enable Camera

# smbios-token-ctl -i 0x0286 --activate
Original Value
       token: 0x0286
        type: bool
       value: false
Activating token...
New value
        type: bool
       value: true

# smbios-token-ctl -i 0x0285
================================================================================
  Token: 0x0285 - Camera (Enable)
  value: bool = false
   Desc: To enable Camera

Last edited by stoorky; 08-02-2022 at 01:59 PM.
 
Old 08-02-2022, 01:59 PM   #12
stoorky
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Quote:
Originally Posted by rtmistler View Post
This is not about Linux, it's your computer.
Yes, at second thought I think so too, see my next post

Last edited by stoorky; 08-02-2022 at 02:18 PM.
 
Old 08-02-2022, 02:10 PM   #13
stoorky
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Quote:
Originally Posted by David Roesch View Post
Most if not all of the BIOS' instructions are read by the computer at initial boot time, before the computer is even aware of what OS it will boot in to.
Given that, I doubt that there is a way to "backfeed" permanent instructions to the BIOS from any OS once that OS has booted.
Your answer helped me to understand. At boot time the BIOS gives or denies access to the camera, depending on that particular BIOS setting. So modifying that BIOS setting from within the OS won't change the given access right until the next reboot.

So, basically, the answer to my question " Can BIOS changes be applied without having to reboot?" is NO, unless the manufacturer provides a specific tool for this. It seems for example that Dell provides such a tool for some of its systems :
Quote:
Dell Client Configuration Toolkit (CCTK) is a packaged software that provides BIOS configuration capability to Dell Optiplex, Latitude, and Precision systems. You can configure the systems in two ways: using Graphical User Interface (GUI) or using Command Line Interface (CLI).
The tool allows a user to make BIOS configuration changes from within the operating system and does not require a reboot.

As a sidenote :
As for disabling the camera, no need for taping or other physical covers, you can just unload the module :
Code:
# modprobe -r uvcvideo
To re-enable the camera :
Code:
# modprobe uvcvideo

Last edited by stoorky; 08-02-2022 at 03:06 PM.
 
Old 08-03-2022, 02:24 AM   #14
David Roesch
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Quote:
Originally Posted by stoorky View Post
Your answer helped me to understand. At boot time the BIOS gives or denies access to the camera, depending on that particular BIOS setting. So modifying that BIOS setting from within the OS won't change the given access right until the next reboot.
Without going in to a heck of a lot technical details, yes, stoorky- you've got the basic idea.
 
Old 08-13-2022, 09:09 AM   #15
flipper8827
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The reason a reboot is required when ever a BIOS setting is changed is so that the complementary medal oxide system storage chips can be flashed with your desired new settings.
 
  


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