2.3 KiB
NixGLHost
Running OpenGL Nix-built binaries on a foreign Linux distro is quite often a challenge. NixGLHost glues a nix-built program to your host system graphics drivers.
Current status: experimental.
How to Use
First of all, build your Opengl program with our custom libglvnd. You can use this project's flake default overlay as a convenience. Let's build glxgears, living in the glxinfo derivation:
nix build .#glxinfo
Let say that your host graphics drivers are stored in /lib/x86_64-linux-gnu/. TODO: explain how to figure out where are the host graphic drivers.
You can run glxgear with your host graphics driver using:
PATH=$(nix build --print-out-paths)/bin:$PATH
nixglhost /lib/x86_64-linux-gnu $(nix build --print-out-paths .#glxinfo)/bin/glxgears
NixGLHost Approach
Re-using the host graphics dynamic libraries turned out being quite challenging.
NixGLHost relies on a patched libGLvnd to inject the host DSOs without polluting the LD_LIBRARY_PATH. You can use the ./overlays/nixpkgs.nix nixpkgs overlay (exposed via flake.nix for external projects) to build a binary with this custom libglvnd.
Here's how everything works:
- Detect the host vendor graphic DSOs via some heuristics.
- Copy the host vendor DSOs to a cache location.
- Modify the cached DSOs runpath to point to the cache. The graphics DSOs depend on each other and won't be able to find each other using the default Nix
LD_LIBRARY_PATH. - Inject the libGLVnd-specific env variables to point to the patched vendor lib.
- Execute the wrapped binary.
This approach won't affect the Nix hermiticity: the only "external" DSOs loaded to the Nix-built program are the host-specific graphics drivers.
Support
- [-] Proprietary Nvidia
- GLX
- EGL
- Cuda
- OpenCL
- Mesa
- GLX
- EGL
- OpenCL
Alternative Approaches
- NixGL: tries to auto detect the host vendor driver, download it again, store it in the nix-store then wraps the nix-built binary and inject the downloaded vendor driver through
LD_LIBRARY_PATH.