RSIM simulates applications compiled and linked for SPARC V9/Solaris using ordinary SPARC compilers and linkers, with the following exceptions.
First, although RSIM supports most important user-mode SPARC V9 instructions, there are a few unsupported instructions. More specifically, all instructions generated by current C compilers for the UltraSPARC-I or UltraSPARC-II with Solaris 2.5 or 2.6 are supported. Unsupported instructions that may be most important on other SPARC systems include 64-bit integer register instructions and quadruple-precision floating-point instructions.
Second, the system trap convention supported by RSIM differs from that of Solaris or any other operating system. Therefore, standard libraries and functions that rely on such traps cannot be directly used. We provide an RSIM applications library to support such commonly used libraries and functions; all applications must be linked with this library. Nevertheless, there are some unsupported traps and related functions (e.g., strftime), and our library has only been tested for application programs written in C. More details are given in Chapter 5.
For faster processing and portability, the RSIM simulator actually interprets applications in an expanded, loosely encoded instruction set format. A predecoder is provided to convert SPARC application executables into this internal format, which is then fed into the simulator.