Pros of riscv-gnu-toolchain

• More actively maintained with frequent updates
• Focused specifically on GNU toolchain for RISC-V
• Better documentation and build instructions

Cons of riscv-gnu-toolchain

• Limited to GNU toolchain, less comprehensive than riscv-tools
• May require more manual configuration for specific use cases
• Potentially steeper learning curve for beginners

Code Comparison

riscv-gnu-toolchain:

./configure --prefix=/opt/riscv
make linux

riscv-tools:

git submodule update --init --recursive
export RISCV=/path/to/install/riscv/toolchain
./build.sh

The riscv-gnu-toolchain repository focuses on building the GNU toolchain for RISC-V, while riscv-tools is a more comprehensive collection of RISC-V software development tools. riscv-gnu-toolchain offers a more streamlined approach for those specifically interested in the GNU toolchain, while riscv-tools provides a broader set of tools but may require more setup and configuration.

Both repositories serve different purposes and cater to different user needs within the RISC-V ecosystem. The choice between them depends on the specific requirements of the project and the developer's familiarity with RISC-V tools.

Pros of riscv-isa-sim

• Focused specifically on RISC-V instruction set simulation
• Lighter weight and more modular
• Easier to integrate into other projects

Cons of riscv-isa-sim

• Less comprehensive toolchain compared to riscv-tools
• May require additional components for a complete development environment
• Limited to simulation, lacking some real hardware debugging features

Code Comparison

riscv-isa-sim (Spike):

void processor_t::step(size_t n)
{
  for (size_t i = 0; i < n; i++)
    step(1);
  update_histogram(n);
}

riscv-tools (GDB):

static void
riscv_software_single_step (struct regcache *regcache)
{
  struct gdbarch *gdbarch = regcache->arch ();
  CORE_ADDR pc = regcache_read_pc (regcache);
  CORE_ADDR next_pc = riscv_next_pc (regcache, pc);
  regcache_write_pc (regcache, next_pc);
}

The riscv-isa-sim code shows a simple stepping mechanism for the simulator, while the riscv-tools code demonstrates a more complex single-step implementation for debugging purposes.

Pros of riscv-boom

• Focuses on a specific RISC-V out-of-order core implementation
• More actively maintained with frequent updates
• Provides a complete SoC design for FPGA prototyping

Cons of riscv-boom

• Narrower scope, limited to BOOM core and related components
• Steeper learning curve for newcomers to out-of-order architectures
• Requires more computational resources for simulation and synthesis

Code Comparison

riscv-boom:

class BoomCore(implicit p: Parameters) extends BoomModule()(p)
  with HasBoomCoreParameters
  with HasL1ICacheBankedParameters
{
  val io = IO(new BoomCoreIO)
  // Core implementation...
}

riscv-tools:

#define MSTATUS_UIE         0x00000001
#define MSTATUS_SIE         0x00000002
#define MSTATUS_HIE         0x00000004
#define MSTATUS_MIE         0x00000008
#define MSTATUS_UPIE        0x00000010

The riscv-boom code snippet shows a Scala class definition for the BOOM core, while the riscv-tools example displays C preprocessor definitions for RISC-V status register bits. This highlights the different focus areas of the two projects: riscv-boom on core implementation and riscv-tools on software development support.

Pros of e203_hbirdv2

• Specifically designed for MCU applications, offering a more focused and optimized solution
• Includes a complete SoC design with peripherals, making it easier to implement in embedded systems
• Provides FPGA bitstreams and demo projects, enabling quick prototyping and testing

Cons of e203_hbirdv2

• Less comprehensive toolchain support compared to riscv-tools
• Limited to a specific core implementation, reducing flexibility for different RISC-V configurations
• Smaller community and potentially less frequent updates

Code Comparison

e203_hbirdv2:

module e203_cpu_top (
  input  clk,
  input  rst_n,
  // Other ports...
);
  // CPU implementation
endmodule

riscv-tools:

#define REGBYTES 8
#define STORE sd
#define LOAD ld

.macro SAVE_GP
  addi sp, sp, -32*REGBYTES
  STORE x1, 1*REGBYTES(sp)
  // More register saves...
.endm

The e203_hbirdv2 code snippet shows the top-level module of the CPU implementation in Verilog, while the riscv-tools example demonstrates assembly macros for context saving, highlighting the different focus areas of these projects.