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The Berkeley Out-of-Order RISC-V Processor

This is the source repository for the RV64G RISC-V superscalar Berkeley Out-of-Order Machine (BOOM), written in the Chisel hardware construction language. BOOM is a synthesizable core that targets ASIC processes. It can run on an FPGA (50 MHz on a zc706), but optimizing it to be an FPGA soft-core is a non-goal.

Feature BOOM
ISA RISC-V (RV64G)
Synthesizable √
FPGA √
Parameterized √
Floating Point (IEEE 754-2008) √
Atomic Memory Op Support √
Caches √
Viritual Memory √
Boots Linux √

Google group: (https://groups.google.com/forum/#!forum/riscv-boom)

For documentation on BOOM visit (https://ccelio.github.io/riscv-boom-doc).

The wiki may also have more information.

Important!

This repository is NOT A SELF-RUNNING repository. To instantiate a BOOM core, please use the Rocket chip generator found in the rocket-chip git repository (https://github.com/ucb-bar/rocket-chip).

BOOM depends on the Chisel project. It also depends on Rocket, uncore, and junction source codes.

Requirements

These instructions assume you have already installed the riscv-tools toolchain.

If you have not, follow additional instructions below.

Directions

To build a BOOM C++ emulator and run BOOM through a couple of simple tests:

   $ git clone https://github.com/ucb-bar/rocket-chip.git
   $ cd rocket-chip
   $ git checkout boom
   $ git submodule update --init
   $ cd riscv-tools
   $ git submodule update --init --recursive riscv-tests
   $ cd ../emulator; make run CONFIG=BOOMCPPConfig

Installing the RISC-V Toolchain

The following (modified) instructions will also build the RISC-V toolchain (if you have not already do so). You will need to set the $RISCV environment variable (where the toolchain will be installed) and you will need to add $RISCV/bin to your $PATH.

   $ export RISCV=/path/to/install/riscv/toolchain
   $ export PATH="${PATH}:$RISCV/bin"
   $ export ROCKETCHIP_ADDONS="boom"
   $ git clone https://github.com/ucb-bar/rocket-chip.git
   $ cd rocket-chip
   $ git checkout boom
   $ git submodule update --init
   $ cd riscv-tools
   $ git submodule update --init --recursive
   $ ./build.sh
   $ cd ../emulator; make run CONFIG=BOOMCPPConfig

For more detailed information on the toolchain, visit the riscv-tools repository.

Using the gem5 O3 Pipeline Viewer with BOOM

The O3 Pipeline Viewer is an out-of-order pipeline viewer included in the gem5 suite. BOOM is capable of generating traces compatible with the pipeline viewer, which is useful for understanding what causes pipeline stalls and flushes.

To generate gem5 compatible traces, first set O3PIPEVIEW_PRINTF in boom/src/main/scala/consts.scala to true:

   val O3PIPEVIEW_PRINTF   = true  // dump trace for O3PipeView from gem5

It is important that all other logging functionality is turned off in src/main/scala/consts.scala:

   val DEBUG_PRINTF        = false // use the Chisel printf functionality
   val DEBUG_ENABLE_COLOR  = false // provide color to print outs. Requires a VIM plugin to work properly :(
   val COMMIT_LOG_PRINTF   = false // dump commit state, for comparision against ISA sim
   val O3PIPEVIEW_PRINTF   = true  // dump trace for O3PipeView from gem5
   val O3_CYCLE_TIME       = UInt(500) // cycle time for O3PipeView

Rebuild and rerun BOOM. You should find the traces (*.out) in emulator/output/. Next, go to your gem5 directory. To generate the visualization run:

   ./util/o3-pipeview.py -c 500 -o pipeview.out --color <TRACE_FILE>

You can view the visualization by running:

   less -r pipeview.out

For more details, visit the gem5 wiki.

More Info

Disclaimer!

The RISC-V privileged ISA and platform specs are still in flux. BOOM will do its best to stay up-to-date with it!

BOOM is a work-in-progress and remains in active development.

FAQ

To be filled in as questions are asked...