In March 2006, the complete design of Sun Microsystems’ UltraSPARC T1 microprocessor was released in open source form, named OpenSPARC T1. In early 2008, its successor, OpenSPARC T2, was also released in open source form. These were the first (and still only) 64-bit microprocessors ever open sourced. They were also the first (and still only) CMT (chip multithreaded) microprocessors ever open sourced. Both designs are freely available from the OpenSPARC.
The OpenSPARC project’s intent is to allow FPGA implementation experts to take what was provided with the latest OpenSPARC T1 release and to further develop the FPGA implementation including work to optimize area and timing of this design and contribute their changes back to this project and to be shared with the community. These downloads include not only the processor design source code but also simulation tools, design verification suites, Hypervisor source code, and other helpful tools. Variants that easily synthesize for FPGA targets are also available.
This is an advanced project, but beginners should examine the docs to get acquainted with the basic concepts. Get your own copy of the OpenSPARC Internals book in free PDF form.