Comment by sumtechguy

Having done a multi targeted project in the 2005 range. I can tell you. The APIs that both systems provide are quite expansive and do quite a bit. However there is a mismatch on details and gaps. In this case the NT mutex system is 'there' in linux however the way it works is subtly different. You have to basically emulate waitforxxxxxxobject set of windows calls. Getting that right and performant can be quite a challenge.

My particular challenge was similar in around how threads were created destroyed and signals between them (such as mutex). We ended up making our own wrappers to insure the different platforms acted the same. Even something simple as just moving between two supposedly 'same' linux distros could be different depending on what the ODM did to their packages and supported libs. Having a dedicated linux object that acts exactly like the windows one would have made that code much simpler to do.

Another place where there is a huge impedance mismatch is in the permission system. In many ways the VMS/NT way is wildly detailed. Linux can do that but you have to emulate it or use it directly and hope you get it right on both sides. There are several places where windows/linux have the same functionality but the APIs are different enough that multi platform support is kinda awful to do.