3.3. Berkeley Out-of-Order Machine (BOOM)


The Berkeley Out-of-Order Machine (BOOM) is a synthesizable and parameterizable open source RV64GC RISC-V core written in the Chisel hardware construction language. It serves as a drop-in replacement to the Rocket core given by Rocket Chip (replaces the RocketTile with a BoomTile). BOOM is heavily inspired by the MIPS R10k and the Alpha 21264 out-of-order processors. Like the R10k and the 21264, BOOM is a unified physical register file design (also known as “explicit register renaming”). Conceptually, BOOM is broken up into 10 stages: Fetch, Decode, Register Rename, Dispatch, Issue, Register Read, Execute, Memory, Writeback and Commit. However, many of those stages are combined in the current implementation, yielding seven stages: Fetch, Decode/Rename, Rename/Dispatch, Issue/RegisterRead, Execute, Memory and Writeback (Commit occurs asynchronously, so it is not counted as part of the “pipeline”).

Additional information about the BOOM micro-architecture can be found in the BOOM documentation pages.