This is mostly ifdefs, but as you can see, Solaris is actually a lot like Linux. They're both more SysV than BSD at core, and most of the differences have more to do with Solaris not using glibc than anything else.
I still need to audit a lot of these changes and understand why they're needed and what the alternative approaches are. After this patch, most of the core functionality needed to build Solaris is here.
athenian200