labwc
Dual graphic card
Is it possible to chose a graphic card as main render output? i have a laptop with an intel and nvidia graphic card i need use intel one to increase battery life
I have a laptop with an Nvidia secondary GPU and, for three years, kept it fully disabled using the acpi_call kernel module to power down the hardware than then a sysfs operation to remove it from the bus. This worked well but is a heavy-handed solution.
Yesterday, I happened to spend some time figuring out PRIME dual-GPU graphics. With the Nvidia hardware powered and on the bus, labwc always seems to prefer the Intel graphics. Even prime-run labwc doesn't make it use the Nvidia chip. Getting some clients to work properly on the secondary GPU (qutebrowser and mpv, for example) required that I configure the Nvidia driver to attach to the DRM subsystem.
You can confirm that labwc is not using the Nvidia hardware by launching labwc and confirming that it does not appear in the output of nvidia-smi. I suspect your problem is really that the driver isn't configured to allow the hardware to be powered down on idle. The Arch wiki entry on PRIME outlines the necessary steps for power control. On my installation of Void Linux, the udev rules described on that page don't take effect; I have to manually enable automatic power control at boot using, e.g., a line in /etc/rc.local.
i have a laptop with an intel and nvidia graphic card
That's what I have in my both old and current laptops. I use only Intel+modesettings, never nvidia, although I've installed nvidia+prime (from Manjaro).
So, if you want to choose a specific one for just labwc, I've got at least some idea as I had to do something similar to avoid using the ASPEED built-in graphics on one of my machines.
Here's the script I came up with to solve it for me. (It runs before labwc is started.)
It notably doesn't play nice with Intel Xe graphics (I need to figure out a way to differentiate that in the libva section) and it doesn't have nvidia bits yet, but those ought to be pretty straightforward to add, if you wanted to lift it wholesale.
Otherwise, should you choose to take inspiration from it, you just need to create an exclusion (like the 'ast' one) for nvidia (if you want to exclude it) or a preference for Intel.
If @ahesford is correct, and the issue is that the device isn't being powered down, then nothing in my script would help you fix that piece.
It's also possible to mix and match, if you wanted, setting labwc to use Intel and then vdpau to use nvidia, or some such, though I've not tested that thoroughly, so YMMV.
