Dromajo - Esperanto Technology's RISC-V Reference Model

Functional verification is key to have a strong RISC-V ecosystem. Esperanto is releasing Dromajo to help the RISC-V community. Dromajo is the Esperanto translation for an emu bird. It is a RISC-V RV64GC emulator designed for RTL co-simulation. This is the emulator used for cosimulation inside Esperanto, but it is designed with a simple API that can be leveraged to other RTL RISC-V cores.

Dromajo enables executing application (such as benchmarks running on Linux) under fast software simulation, generating checkpoints after a given number of cycles, and resuming such checkpoints for HW/SW co-simulation. This has proven to be a very powerful way to capture bugs, especially in combination with randomized tests.

Dromajo's semantic model is based on Fabrice Bellard's RISCVEMU (later renamed TinyEMU), but extensively verified, bug-fixed, and enhanced to take it to ISA 2.3/priv 1.11.

Building

mkdir build
cd build
# Debug build
cmake ..
# Release build Ofast compile option
cmake -DCMAKE_BUILD_TYPE=Release ..
make

The resulting artifacts are the dromajo simulator and the libdromajo_cosim.a library with associated dromajo_cosim.h header file.

Check the setup.md for instructions how to compile tests like booting Linux and baremetal for dromajo.

Usage

The co-simulation environment will link with the libraries and usage will depend on that, but the src/dromajo.c utility allows for standalone simulation of RISC-V ELF binaries.

./dromajo
error: missing config file
usage: ./dromajo [--load snapshot_name] [--save snapshot_name] [--maxinsns N] [--memory_size MB] config
       --load resumes a previously saved snapshot
       --save saves a snapshot upon exit
       --maxinsns terminates execution after a number of instructions
       --terminate-event name of the validate event to terminate execution
       --trace start trace dump after a number of instructions
       --memory_size sets the memory size in MiB (default 256 MiB)

./dromajo path/to/your/coremark.riscv
...