On my laptop manufacturer’s website there are instructions (see https://www.tuxedocomputers.com/en/Infos/Help-Support/Instructions/Brightness-for-120-Hz-and-144-Hz-displays_1.tuxedo) to fix brightness control failures in a system using grub, but I do not know how to apply this to the different booting architecture of Qubes OS, since the file /etc/default/grub does not exist in Qubes OS and I am not familiar with the Qubes OS boot architecture.
The instructions on the website are the following:
sudo nano /etc/default/grub
add the parameters acpi_osi= acpi_os_name=Linux i915.enable_dpcd_backlight to the variable GRUB_CMDLINE_LINUX_DEFAULT,
update grub and reboot.
Does anyone know where these parameters and/or their values or adapted parameters/values can be placed in the Qubes OS system to have the same effect?
For 4.0, the difference depends on whether it is installed with legacy mode or UEFI mode. In the former mode, grub is will be used but not in the latter, so that that file is not exists but there is another one called xen.cfg instead.
Thank you for this input. Indeed my laptop is installed with UEFI mode and this is the place where to put kernel parameters, so I will mark this as solved.
As far as the brightness control goes: I appended the parameters as kernel parameters in the /boot/efi/EFI/qubes/xen.cfg file, but a reboot did not reveal any changes to brightness control. I will contact my manufacturer and see if I can get another hint from them, since these command line parameters from the instructions might be not be applicable to my laptop.
Hi @chrfre ,
with the cat /proc/cmdline command, you see the kernel options of your current kernel. So the first check is to verify if your wanted backlight options are present in this output.
Hi @devnull, you are right. The original issue has not been resolved up to date. However a working solution to the main question of this post has been provided which is why it is marked as solved.
Apologies for the late reaction. I’m encountering exactly the same problem you did, and the solution isn’t working for me either. Could you please enlighten me to the working solution you have found?
?
As my introduction refers to another issue I am wondering if you mean the broader issue of backlight control or the issue of passing on backlight kernel parameters to the dom0 kernel correctly in UEFI mode. The latter has been answered by @kommuni in the marked answer, but if you have further questions about it, feel free to ask, also about the other issue.
I am very busy at the moment. I will answer as quickly as possible, but it might take a few days.
@ryuu, you are right. The title suggests what you seem to be hoping to find. I need to change it to better reflect what was actually achieved in this thread, but I do not see a button to do it at the moment. This thread is actually about finding the right place to pass on brightness control parameters to the kernel. What the kernel does with them once they correctly appear in its command line call is another issue.
It appears to me that even if the parameters are passed on to the kernel correctly, they have no effect. I thought that it might be a missing driver issue, which is why I opened another thread: