[Feature] Idle power-off (RTD3 / GC6) for laptop RTX in Hybrid mode
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Nobody has claimed this yet.
Assessment
- Difficulty
- 5/5
- Estimated time
- Over a week
- Newbie friendliness
- 25/100
- Issue type
- Feature
- Clarity
- Mostly clear
- Activity status
- Active
- Tech stack
- macos, rust
- Domain
- backend, operating-systems
Research direction
Start by tracing the driver’s power state handling from the setPowerState log message and investigate how the NVIDIA Resource Manager standby path relates to the ACPI PEG1 PG01 _OFF method. The report says that calling _OFF after RM standby powers down the GPU and resumes without a crash, while idle macOS leaves the GPU at power state 2. Done means the GPU can enter runtime idle power-off and resume reliably when it is needed; the issue names no source files or tests.
Written by the indexing model from the issue text.
Description
What should it do, and why does it matter to you?
Is runtime idle power-off (RTD3/GC6) something you plan to support, at least when no app is using the GPU?
My setup is unusual
First of all, to be clear, my scenario is not the standard one: the internal panel is driven by the integrated Intel UHD via NootedGreen (with some tweaks of ours), while NullMoth runs in parallel handling only Metal acceleration on the RTX 4050 (and HDMI when connected).
From what I noticed, NullMoth expects the NVIDIA GPU to drive the display directly, so what I’m asking may be outside the scope of your project. Still, idle power management for the dGPU would be a big gain, including for people who only use an external display occasionally.
Machine and environment
Laptop: Dell G15 5530 (BIOS 1.35.0, MUX in Hybrid mode)
Hardware: i5-13450HX + RTX 4050 Laptop (AD107, 10de:28e1)
System: macOS 26.7.1, OpenCore 1.0.8 (SMBIOS MacBookPro16,2)
NullMoth: 2.6.0 (nvfb=1 nvaccel=1 nvfbheads=4 -nvkmsnosmooth, ResizeAppleGpuBars=-1)
Linux comparison: Fedora 44 (kernel 7.2.13, open driver 615.78.08)
The problem: the RTX never powers off when idle
On Linux, this same machine puts the dGPU into D3 without issues (Runtime D3 status: Enabled (fine-grained) with Video Memory Off). Dell’s ACPI has the path ready on the PCIe bridge (_SB.PC00.PEG1 with PG01 in _PR0/_PR3, where _OFF cuts power to the slot).
On macOS with NullMoth, however:
The RTX stays stuck at CurrentPowerState = 2 (of 3) all the time, idle or after a Metal test. The PEG1 bridge also stays at 2.
The idle card sits between 50 and 59 °C. AGCInfo shows poweredOffByAGC = No.
The battery impact is high: package C-state residency drops from ~88% to ~0.3%, and idle package power jumps from ~8 W to 13–18 W.
When macOS requests a power state change, dmesg only shows:
NVRM-xnu: power: setPowerState %lu (gpu %s, adapter %s) - nothing to do
Looking at the strings in the binary, the RTD3/GC6 logic seems to be there in the Resource Manager (references to JT revision, GC6 entry, RTD3 ACPI support, etc.). It looks like the RM would know how to handle it, but the macOS layer doesn’t trigger the transition when the GPU goes idle.
Relation to sleep (S0 Deep Idle)
In tests we did here, we saw that calling PG01._OFF via ACPI right after RM standby works smoothly, and resume brings the GPU back without crash or panic.
- Dominant language
- Rust
- Stars
- 2.5k
- Forks
- 233
- Avg merge
- 3d 14h
- Merged PRs (30d)
- 14
Getting set up
This project ships no dev container, Dockerfile or contributing guide, so setting up is up to you: start from its README, and see our first-contribution guide for the general steps.
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
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