autobot
The environment variable LIBGL_ALWAYS_SOFTWARE=1 switches Mesa to use CPU for calculations. The graphics card continues to function normally and is managed by its driver. When I enable software rendering, the image quality seems a bit nicer. Previously, I noticed that colors change between CPU and GPU rendering, which might trigger the FRC module on my monitor. So, I'm currently using only software rendering, but I can still manage the graphics card through the driver (I have it set to 6-bit). I think for cards where the driver enables dithering, software rendering won't fix the issue.
Below is the system information for the software rendering mode:
$ inxi -G
Graphics:
Device-1: Intel DG2 [Arc A770] driver: i915 v: kernel
Display: x11 server: X.Org v: 21.1.11 with: Xwayland v: 23.2.6 driver: X:
loaded: modesetting unloaded: fbdev,vesa dri: swrast gpu: i915
resolution: 1920x1080~60Hz
API: EGL v: 1.5 drivers: iris,swrast platforms: gbm,x11,surfaceless,device
API: OpenGL v: 4.6 compat-v: 4.5 vendor: mesa v: N/A renderer: llvmpipe (LLVM 18.1.3 256 bits)
API: Vulkan v: 1.3.275 drivers: N/A surfaces: xcb,xlib
$ lsmod | grep i915
i915 4329472 5
drm_buddy 20480 2 xe,i915
ttm 106496 3 drm_ttm_helper,xe,i915
drm_display_helper 253952 2 xe,i915
cec 94208 2 xe,i915
i2c_algo_bit 16384 2 xe,i915
video 73728 2 xe,i915
llvmpipe (LLVM 18.1.3 256 bits)is the CPU (software) render.
The lsmod command indicates that the video driver is loaded.
To “disable” the video card, you need to blacklist its driver. In this case, Mesa will also switch to software rendering, but the video card driver won't be loaded.
