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ifazral

Member

Registered: 2026-06-21

Posts: 3

[SOLVED] KWin Wayland defaults to NVIDIA (card0) instead of Intel

Hello everyone,

I am running a fully up-to-date, vanilla Arch Linux system on an ASUS Optimus laptop (Intel i7-13650HX & NVIDIA RTX 4060). I am using KDE Plasma 6 (Wayland) inside a systemd-boot environment with Unified Kernel Images (UKI). (ASUS ROG Strix G16 G614JV (2023))

The issue: At boot, the NVIDIA dGPU always gets assigned to `card0`, while the Intel iGPU gets assigned to `card1`. Because of this hardware/driver initialization order, `kwin_wayland` automatically hooks into the NVIDIA card (occupying ~7MiB of VRAM and keeping the dGPU awake at 1W-4W during idle desktop usage).

What I have tried:
1. I checked my kernel command line; I do not have `nvidia_drm.fbdev=1` active anymore (it was removed from the UKI profile).
2. I tried rearranging the `MODULES=(...)` array inside `/etc/mkinitcpio.conf` to force load `i915` and `xe` before `nvidia`, but the dGPU still wins the race and becomes `card0`.
3. Trying to force KWin via `KWIN_DRM_DEVICES` to use `card1` causes the Plasma session to crash into a Core Dump during login.

It seems like the UEFI/BIOS initializes the PCIe lanes for the dGPU slightly faster than the iGPU, forcing the kernel to register NVIDIA first. Is there a reliable way to solve this layout issue under Wayland without breaking the session?

Here are my system logs:
- DRI by-path output: https://paste.rs/eBIJ9
- bootctl list output: https://paste.rs/TTTUf
- nvidia-smi output: https://paste.rs/GdngY
- Full journalctl -b 0: https://paste.rs/0xu9a

Thank you in advance for your time and help!

"Edit:
Answer: Use method member "seth" mentioned https://wiki.archlinux.org/title/KDE#Me … -specific) then after reboot see if gpu can suspend itself
cat /sys/bus/pci/devices/0000:01:00.0/power/control
cat /sys/bus/pci/devices/0000:01:00.0/power/runtime_status

or you can see the wiki it probably knows better than me https://wiki.archlinux.org/title/PRIME# … Management
or
https://download.nvidia.com/XFree86/Lin … ement.html

if it doesn't say auto and suspended then you should do:
sudo nano /etc/modprobe.d/nvidia-power.conf
options nvidia NVreg_DynamicPowerManagement=0x03

sudo nano /etc/udev/rules.d/80-nvidia-pm.rules
# Enable runtime PM for NVIDIA VGA/3D controller devices on driver bind
ACTION=="bind", SUBSYSTEM=="pci", ATTR{vendor}=="0x10de", ATTR{class}=="0x030000", TEST=="power/control", ATTR{power/control}="auto"
ACTION=="bind", SUBSYSTEM=="pci", ATTR{vendor}=="0x10de", ATTR{class}=="0x030200", TEST=="power/control", ATTR{power/control}="auto"

# Disable runtime PM for NVIDIA VGA/3D controller devices on driver unbind
ACTION=="unbind", SUBSYSTEM=="pci", ATTR{vendor}=="0x10de", ATTR{class}=="0x030000", TEST=="power/control", ATTR{power/control}="on"
ACTION=="unbind", SUBSYSTEM=="pci", ATTR{vendor}=="0x10de", ATTR{class}=="0x030200", TEST=="power/control", ATTR{power/control}="on"

# Enable runtime PM for NVIDIA VGA/3D controller devices on adding device
ACTION=="add", SUBSYSTEM=="pci", ATTR{vendor}=="0x10de", ATTR{class}=="0x030000", TEST=="power/control", ATTR{power/control}="auto"
ACTION=="add", SUBSYSTEM=="pci", ATTR{vendor}=="0x10de", ATTR{class}=="0x030200", TEST=="power/control", ATTR{power/control}="auto"

then reboot it."

Last edited by ifazral (2026-06-22 05:35:46)

ifazral

Member

Registered: 2026-06-21

Posts: 3

Re: [SOLVED] KWin Wayland defaults to NVIDIA (card0) instead of Intel

System Context: ASUS ROG/TUF (or similar Intel + NVIDIA hybrid laptops), KDE Plasma, KWin Wayland, Linux-Zen Kernel (7.x+).

The Problem:

When running on battery, the discrete NVIDIA GPU (RTX 40xx/30xx) refuses to stay in its deep sleep state (`D3cold` / 0 Watts). Instead, background processes or `kwin_wayland` constantly poll the GPU every 5 seconds, causing a devastating active <-> suspended ping-pong loop. This results in high idle power draw (20W+), overheating, and poor battery life. Legacy tools like `supergfxctl` are now deprecated or highly unstable on modern kernels.

The Permanent Solution

This fix utilizes next-gen eBPF LSM hooks to intercept and block hardware access syscalls at the kernel level, combined with forced PCI runtime power management.

1. Install the eBPF-based GPU Manager (`cardwire`)

`cardwire` tricks misbehaving applications into thinking the NVIDIA card doesn't even exist by returning an immediate `-ENOENT` (File/Device not found) error. Install it from the AUR:

yay -S cardwire

2. Configure Cardwire for NVIDIA

Create the missing configuration directory and file:

sudo mkdir -p /etc/cardwire
sudo nano /etc/cardwire/cardwire.toml

Paste the following configuration (enabling the experimental NVIDIA block is mandatory):

auto_apply_gpu_state = true
experimental_nvidia_block = true
battery_auto_switch = false
battery_auto_switch_mode = "hybrid"

3. Enable NVIDIA Dynamic Power Management

Tell the NVIDIA driver that it is allowed to power down when idle:

sudo nano /etc/modprobe.d/nvidia-power.conf

Add this line:

options nvidia NVreg_DynamicPowerManagement=0x02

4. Force the PCI Power Switch to Auto (udev Rule)

By default, the Linux kernel keeps the NVIDIA PCIe slot's master power switch set to `on`. We need to force it to `auto` so it can actually cut the power:

sudo nano /etc/udev/rules.d/80-nvidia-pm.rules

Paste these 3 exact rules to cover the GPU and its sub-components (Audio/USB):

ACTION=="add", SUBSYSTEM=="pci", ATTR{vendor}=="0x10de", ATTR{class}=="0x030000", ATTR{power/control}="auto"
ACTION=="add", SUBSYSTEM=="pci", ATTR{vendor}=="0x10de", ATTR{class}=="0x030200", ATTR{power/control}="auto"
ACTION=="add", SUBSYSTEM=="pci", ATTR{vendor}=="0x10de", ATTR{class}="0x040300", ATTR{power/control}="auto"

5. Fire Up the Service and Reboot

Enable the backend daemon, set your initial mode, and restart your machine to apply the kernel parameters:

sudo systemctl enable --now cardwired.service
cardwire set integrated
sudo reboot

Upon reboot, running `cat /sys/bus/pci/devices/0000:01:00.0/power/runtime_status` should finally report `suspended`

CRITICAL LIMITATION / THE UNRESOLVED CAVEAT

While this setup provides a massive battery life extension, it is not 100% automated if you choose to boot into Hybrid mode, due to the architectural design of Wayland.

The KWin DRM Binding Issue: If you boot your system while Cardwire is set to Hybrid, `kwin_wayland` initializes at the login screen and immediately binds to the NVIDIA card (`card0`).
Once KWin grabs a hold of the NVIDIA DRM node, it refuses to let go. If you try to run `cardwire set integrated` later on, KWin will block the GPU from entering its deep sleep state, and the card will stay `active`.

To safely drop back down to `suspended` (0W) mode without dealing with a persistent wake-state, you must do one of the following:

1. Make sure to run `cardwire set integrated` before you reboot or shut down your system, ensuring the next boot forces KWin onto the Intel card exclusively.
2. Or you can use a script:

Automated Hybrid Mode for Cardwire on KWin Wayland (Fixing DRM Binding via KDE User-Space)

The Trick:

Shift the automation entirely into the KDE Plasma User-Space lifecycle:

1. On Shutdown: Use KDE Plasma's native logout hook to force Cardwire to `integrated` mode the exact millisecond you click the shutdown/reboot button. This guarantees that D-Bus and `cardwired` are still 100% alive.
2. On Boot: The system boots safely with the NVIDIA card hidden. Once you log in, a KDE Autostart script enforces a brute-force 30-second delay. This allows KWin and Xwayland to completely finish their hardware scanning and lock onto the iGPU before Cardwire safely flips the switch back to `hybrid` mode.

---

Implementation

1. Create the KDE Plasma Shutdown Hook

This script runs immediately when you trigger a shutdown, reboot, or logout sequence from the desktop UI.

mkdir -p ~/.config/plasma-workspace/shutdown/
nano ~/.config/plasma-workspace/shutdown/set-integrated-before-die.sh

Paste the following lines:

#!/bin/bash
/usr/bin/cardwire set integrated

Make it executable:

chmod +x ~/.config/plasma-workspace/shutdown/set-integrated-before-die.sh

2. Create the Delayed Hybrid Boot Script

This script acts as the background timer, waiting out KWin's initial hardware probe window.

sudo nano /usr/local/bin/cardwire-boot-hook.sh

Paste the following lines:

#!/bin/bash
sleep 30
/usr/bin/cardwire set hybrid

Make it executable:

sudo chmod +x /usr/local/bin/cardwire-boot-hook.sh

3. Create the Desktop Autostart Trigger

This desktop entry ensures the background timer starts right after your desktop panels load.

mkdir -p ~/.config/autostart/
nano ~/.config/autostart/cardwire-hybrid-trigger.desktop

Paste the following configuration:

[Desktop Entry]
Type=Application
Name=Cardwire Hybrid Trigger
Exec=/usr/local/bin/cardwire-boot-hook.sh
Hidden=false
NoDisplay=false
X-GNOME-Autostart-enabled=true
X-KDE-Autostart-after=panel

---

Result

Your system gracefully logs off in `integrated` mode every single time. On the next boot, KWin is forced to map entirely to your iGPU. 30 seconds after you log in, `hybrid` mode arms itself seamlessly.

Running `nvidia-smi` will show No running processes found, allowing your dGPU to sit completely powered down at 0 Watts (`suspended`) until you explicitly invoke it with `prime-run`.

seth

Member

From: Won't reply 2 private help req

Registered: 2012-09-03

Posts: 76,896

Re: [SOLVED] KWin Wayland defaults to NVIDIA (card0) instead of Intel

I'm not gonna read that WOT and just assume it's some AI nonsense but you were looking for https://wiki.archlinux.org/title/KDE#Me … -specific)

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ifazral

Member

Registered: 2026-06-21

Posts: 3

Re: [SOLVED] KWin Wayland defaults to NVIDIA (card0) instead of Intel

I tried this method today, and it seems to really work. My previous method worked too, but it didn't use 7 MB of locked VRAM. The current method does use it, but since the driver isn't rendering, it can enter a suspended state using d3cold.
But I still needed to change nvidia-power.conf and 80-nvidia-pm.rules without them card couldn't suspend itself.
Also wiki page for power management in nvidia: https://wiki.archlinux.org/title/PRIME# … Management

Last edited by ifazral (2026-06-22 05:24:21)

richardm

Member

Registered: 2023-02-19

Posts: 8

Re: [SOLVED] KWin Wayland defaults to NVIDIA (card0) instead of Intel

On my kernel command line:

initcall_blacklist=simpledrm_platform_driver_init

...stabilized my /dev/dri/cardx and /dev/dri/renderD1xx relationships and made them congruent with PCI address ordering.  It's been very helpful when steering kwin and others to specific cards.  Unfortunately you lose early boot text.