WelcomeWelcome | FAQFAQ | DownloadsDownloads | WikiWiki

Author Topic: [SOLVED] Backlight level: kernel parameter to set it  (Read 1052 times)

Offline paskali

  • Jr. Member
  • **
  • Posts: 71
[SOLVED] Backlight level: kernel parameter to set it
« on: December 10, 2011, 06:32:55 AM »
Hi all, i am new on this forum and i am new about TinyCore Linux. Just in these days i am trying it;
however i have a problem which the solution may be good usefull for a lot of you.
OK:
i start TinyCore linux from my dos partition with linld or loadlin. I have an old pentium 3 laptop but that does work very fine for me. Usually i set backilght level at 50/60% and not to 100%, this increase battery life by making screen readable the same; however i make this setting in battery and ac adapter mode, no any difference between them. Anytime Windows XP does start, set backlight to 100% by it self, i had to change the values of two registry keys and now it does not change any more backlight level to 100%. My problem is simple:
what kernel parameter must i use to set backlight level or to not change it? I do not know very well kernel 3 but i think there is an acpi parameter good for my problem.
Therefore i want to make Linux start as well as Windows XP, it have not to change backlight level to 100% but either set it to 50/60% or to keep it at the level setted on BIOS.
Do you understand?
Thanks!
« Last Edit: December 10, 2011, 09:15:48 AM by zemir »

Offline Rich

  • TinyCore Moderator
  • Hero Member
  • *****
  • Posts: 5319
Re: Backlight level: kernel parameter to set it
« Reply #1 on: December 10, 2011, 06:42:42 AM »
Hi zemir
Try xbacklight, it's in Xorg-7.5-bin.tcz.

Offline paskali

  • Jr. Member
  • **
  • Posts: 71
Re: Backlight level: kernel parameter to set it
« Reply #2 on: December 10, 2011, 08:13:22 AM »
Yes, may be a solution but if i use microcore that start console mode (no X) the problem does not resolve in this way. It is indipendent from Xserver, it is a acpi isue, kernel load laptop module and set backlight at 100% because the laptop works with ac adapter. I do not want this, i want that kernel leaves backilght as well as i have setted it.

Offline paskali

  • Jr. Member
  • **
  • Posts: 71
Re: Backlight level: kernel parameter to set it
« Reply #3 on: December 10, 2011, 09:14:24 AM »
Hi all, i have solved by starting kernel with this parameter:
laptop acpi_backlight=vendor

Offline HansJoachmi1

  • WikiUser
  • *
  • Posts: 1
Re: [SOLVED] Backlight level: kernel parameter to set it
« Reply #4 on: March 08, 2017, 06:23:33 AM »
Hi,
i've tried to start tcl over PXE with Syslinux and the following configuration:

Code: newbielink:javascript:void(0); [nonactive]
LABELTCL
 kernel /kernels/tcl/vmlinuz
 APPEND  laptop acpi_backlight=vendor initrd=/kernels/tcl/core.gz

but it seems it has no effect.
Do I have to recomplile the kernel with the parameters or isnt the Syslinux configuration correct?

best Regards
Joachim

Offline polikuo

  • Full Member
  • ***
  • Posts: 157
Re: [SOLVED] Backlight level: kernel parameter to set it
« Reply #5 on: March 08, 2017, 06:40:59 PM »
LABELTCL
 kernel /kernels/tcl/vmlinuz
 APPEND  laptop acpi_backlight=vendor initrd=/kernels/tcl/core.gz

Hi, HansJoachmi1.
You forgot the space between LABEL and TCL:
Quote
LABEL TCL   ### with space ###
 kernel /kernels/tcl/vmlinuz
 APPEND  laptop acpi_backlight=vendor initrd=/kernels/tcl/core.gz
I'm not sure if "acpi_backlight=vendor" will work thought.
« Last Edit: March 08, 2017, 06:43:43 PM by polikuo »

Offline Scampada

  • Full Member
  • ***
  • Posts: 164
Re: [SOLVED] Backlight level: kernel parameter to set it
« Reply #6 on: March 15, 2017, 12:51:34 PM »
Is your question answered yet? I see the [SOLVED] marker above but no corresponding posts below.

If you want to control your backlight brightness level from within console mode try echoing and catting /sys/class/backlight/acpi_video0/brightness.
You can tune brightness level very precisely doing so, and even make it much more dark then any X widget allows.
There are even Fx buttons working for changing brightness level. You only have to have the relevant module loaded.
IIRC it's in graphics-KERNEL-tinycore.tcz.

You can see how I utilized it in my own installation.
https://pp.userapi.com/c626516/v626516354/4fa09/x_UNzNwgJo4.jpg
https://pp.userapi.com/c626516/v626516354/4fa00/T_F5RLxwPIQ.jpg
The winning entries in UNIX users' hymns competition were 'What's the buzz, tell me what's happening' and 'Strange Thing Mystifying' songs from A.L.Webber's musical.

Tiny Core Linux. Like Gentoo, except Gentoo is easier.