Here lives the TEM VHDL library.
This is about a soft core 32bits CPU with MMU, cache and FPU. It is based on the 32bits SPARCv8 standard.
It comes with enough peripherals to implement a computer in a FPGA, something that behaves as a SPARCstation5 and can run many OSes for these computers : Linux, NetBSD, OpenBSD, SunOS, Solaris and NextSTEP.
Just try it !
Questions, support :