Once upon a time I maintained a so-called "Solaris Drivers Resource". I pulled together different tidbits of information which were difficult to find by common means. When I started to work at Sun I had to stop these activities due to a possible conflict of interests.
BTW, my advice for developers: Get a source license. With SCSL program in place this is easier now than it was in my time. Or switch to Linux, which is what I did.
I keep some historic tarballs for a reference below.
Good Solaris drivers are written in C because C++ sucks. However on February 26, 1998 cluster guys filed a bug 4115715, "kadb input line length too small for C++". The pressure to write in C++ is high due to large number of incompetent developers.