ZLUDA/zluda_preload

This crate is a last resort Linux-specific solution. Most of the time we can inject ourselves into a process by having users set LD_LIBRARY_PATH. Unfortunately, there is software out there which dynamically links to CUDA and CUDA performance libraries using RPATH. On Linux, dynamic linker operates using approximately this algorithm:

• If path contains / treat the name as a (possibly relative) path and just use it
• Otherwise return the first that succeeds:
  • Library with this name already loaded into the process
  • Try paths in DT_RPATH (if DT_RUNPATH is not present)
  • Try paths in LD_LIBRARY_PATH
  • Try paths in DT_RUNPATH
  • Try system paths

In order to defeat DT_RPATH this library needs to be preloaded with LD_PRELOAD. On initialization we also preload all the performance libraries. We also hijack dlopen and on every call to dlopen that tries to open a CUDA library we redirect it to our libraries

We also expose zluda_dlopen_noredirect for the purpose of tracing libraries so they can load real underlying library and not just get redirected to themselves