[Linux] Missing .sog files?


Sometimes on Linux you may get “unable to load dynamic library” errors for .sog files. Like this:

00:00:00     0MB WARNING |  unable to load dynamic library: /home/stephen/solidangle/mtoa/2014/xgen_procedural.sog: cannot open shared object file: No such file or directory 

or this:

00:00:00     0MB WARNING |  unable to load dynamic library: /usr/apps/houdini/houdini-13.0.343/htoa/arnold_plugins/driver_houdini.sog: cannot open shared object file: No such file or directory 

Don’t worry about the “.sog” part. In most cases, Arnold isn’t actually looking for a .sog file. Arnold is trying to load a .so file, and either the .so itself or a dependency is missing. The “.sog” is printed by mistake in the log message (and this is fixed in the next Arnold version).

So (heh) focus your investigation on why Arnold couldn’t load the .so file (try running ldd on it).

In the two examples above:

  • xgen_procedural.so couldn’t be loaded because LD_LIBRARY_PATH didn’t include the Maya lib folder, so all the tbb-related libraries were missing.
  • driver_houdini.so was missing some Houdini dependencies, but in this case it was being loaded into MtoA, so driver_houdini wasn’t needed and the warning could be safely ignored.

What’s a .sog?
If a plugin has a .sog extension, AiLoadPlugins() will load the plugin with RTLD_GLOBAL, which means the symbols from the plugin will be globally exposed and available to other plugins.

.sog is a Maya naming convention for an .so to be dlopen’ed with RLD_GLOBAL

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