Kristy Vu: LEON3 Emulator for SCOORE

Kristy Vu is a senior student majoring in Electrical Engineering and Computer Engineering at UC Davis. During the summer of 2005, she had an opportunity to participate in Summer Undergraduate Research Fellowship - Information Technology (SURF-IT) Program, supported by National Science Foundation (NSF), at University of California, Santa Cruz. She joined Santa Cruz Out-of-Order RISC Engine (SCOORE) research team, leaded by Jose Renau, a professor from University of California, Santa Cruz.

SCOORE is an out-of-order SPARC V8 processor synthesizable on FPGAs and ASIC. In her immediate project, an emulator that is binary compatible with SCOORE was to be designed in order to test SCOORE. The research team made use of the available open source code from QEMU to emulate LEON3 architecture. LEON is a new architecture based on SPARC created in 1997 when Giri Gaisler bought a SPARC license from Sun Microsystems. Leon is very similar to SPARC even though its hardware access and memory management are different from SPARC. In the project, the UART (Universal Asynchronous Receiver/Transmitter) controller is the main component of the serial communications subsystem. The UART transmits the individual bits in a sequential fashion after taking bytes of data. At the destination, a second UART re-assembles the bits into complete bytes. When receiving data from a peripheral device or a modem, the UART performs serial-to-parallel conversion on data. Meanwhile, when receiving data from the CPU, it performs parallel-to-serial conversion.

The project was be success in creating a CPU/System emulator that runs on a variety of platforms (Unix, Linux, Windows, Mac) and is able to emulate many different architectures. However, the fast input / output problem still remained at the end of the program, and there was a need of making sure that the outputs are consistent. After fixing these problems, the emulator should be good to be used in testing SCOORE system.