Re: Empty /sys/class/backlight

[Detlef Vollmann <dv@vollmann.ch>]

On 10/5/25 18:07, Dan Ritter wrote:
> Detlef Vollmann wrote:
> > Hello,
> >
> > on my laptop (Lenovo X250) I run Debian testing.
> > On a recent upgrade the kernel was updated from 6.12.38+deb13-rt-amd64
> > to 6.16.3+deb14-rt-amd64 (and now to 6.16.9+deb14-rt-amd64).
> >
> > With kernel 6.16 I lost /sys/class/backlight/intel_backlight.
> > I also don't have the i915 module anymore, which I suspect might
> > be related.
>
> Very likely. Does it exist in /lib/modules/6.16.9+deb14-rt or
> similar? If so, can you modprobe it?

No, it doesn't exist anymore:
modprobe: FATAL: Module i915 not found in directory 
/lib/modules/6.16.9+deb14-rt-amd64

> Also: why are you using the RT build?

I'm using it on all my machines for a very long time now
as I sometimes need some realtime guarantees.

It might not make a big difference these days.

  Detlef