When setting up my new work laptop (replacing the more than eight years old X270 that I used before), I found that the freshly installed Debian unstable was unable to produce any kind of graphics output. X11 complained about not finding any screens, and the text console also broke as soon as the kernel tried configuring it. Long story short: Turns out that Linux 6.12, as shipped with Debian unstable, is simply too old for Intel Arc 130V/140V graphics and/or Intel Lunar Lake / Core 258V CPUs. With Linux 6.14, everything works right out of the box.

Luckily, you can just install Ubuntu kernels on Debian. So, solving this issue was as simple as issuing the following commands:

wget \
  https://kernel.ubuntu.com/mainline/v6.14/amd64/linux-headers-6.14.0-061400-generic_6.14.0-061400.202503241442_amd64.deb \
  https://kernel.ubuntu.com/mainline/v6.14/amd64/linux-headers-6.14.0-061400_6.14.0-061400.202503241442_all.deb \
  https://kernel.ubuntu.com/mainline/v6.14/amd64/linux-image-unsigned-6.14.0-061400-generic_6.14.0-061400.202503241442_amd64.deb \
  https://kernel.ubuntu.com/mainline/v6.14/amd64/linux-modules-6.14.0-061400-generic_6.14.0-061400.202503241442_amd64.deb
sudo apt install \
  ./linux-headers-6.14.0-061400_6.14.0-061400.202503241442_all.deb \
  ./linux-headers-6.14.0-061400-generic_6.14.0-061400.202503241442_amd64.deb \
  ./linux-modules-6.14.0-061400-generic_6.14.0-061400.202503241442_amd64.deb \
  ./linux-image-unsigned-6.14.0-061400-generic_6.14.0-061400.202503241442_amd64.deb

The new kernel version is automatically picked up by GRUB, so one reboot later everything worked as intended.