docs: add Goban multi-core documentation and sync recent GemminiBall updates

content/.order.json

@@ -3,5 +3,9 @@
   "Overview.md",
   "Tutorial",
   "Building Your Own Hardware Designs.md",
-  "Buckyball ISA.md"
+  "Buckyball ISA.md",
+  "Guide",
+  "GemminiBall Architecture.md",
+  "Verilator Simulation and CI.md",
+  "Development Workflow and Build System.md"
 ]

content/en/Guide/Development Workflow and Build System.md

@@ -0,0 +1,278 @@
+# Development Workflow and Build System
+
+## Overview
+
+Buckyball provides a streamlined development environment using Nix Flakes, with tools like `bbdev` for managing hardware simulation, compilation, and testing. This guide covers the build system, common workflows, and troubleshooting.
+
+## Initial Setup
+
+### Using Nix Flakes
+
+Nix Flakes provides reproducible development environments with all required tools:
+
+```bash
+# Install Nix (if not already installed)
+curl --proto '=https' --tlsv1.2 -sSf -L https://install.determinate.systems/nix | sh
+
+# Enable Flakes (if not enabled by default)
+nix flake update
+```
+
+### Entering the Development Environment
+
+```bash
+nix develop
+```
+
+This command sets up:
+- Scala/Chisel RTL development tools
+- Verilator for hardware simulation
+- C/C++ compiler for software
+- Test frameworks and dependencies
+- Pre-commit hooks
+
+### Full Repository Initialization
+
+The `build-all.sh` script automates the complete setup process:
+
+```bash
+cd buckyball
+./scripts/nix/build-all.sh
+```
+
+**Setup Steps** (can be skipped with `--skip N`):
+
+1. Install bbdev
+2. Compile the compiler toolchain
+3. Pre-compile RTL sources
+4. Install bebop (simulation framework)
+5. Pre-compile test workloads
+6. Build waveform-mcp module
+7. Install pre-commit hooks
+
+**Options:**
+
+```bash
+# Skip specific steps
+./scripts/nix/build-all.sh --skip 2 --skip 5
+
+# Verbose output
+./scripts/nix/build-all.sh --verbose
+
+# Install dependencies in Nix store (default)
+./scripts/nix/build-all.sh --install-in-nix
+```
+
+## bbdev Tool
+
+`bbdev` is the primary interface for hardware simulation and build management in Buckyball.
+
+### Basic Usage
+
+```bash
+bbdev <command> [options]
+```
+
+### Verilator Simulation
+
+Run RTL simulations using the Verilator backend:
+
+```bash
+# Basic simulation run
+bbdev verilator --run '<simulation-options>'
+
+# Common simulation options
+bbdev verilator --run \
+  '--jobs 16 \
+    --binary <workload-name> \
+    --config sims.verilator.BuckyballToyVerilatorConfig \
+    --batch'
+```
+
+**Workload Examples:**
+
+- `ctest_vecunit_matmul_ones_singlecore-baremetal`: Single-core matrix multiplication test
+- `ctest_toy_add-baremetal`: Toy vector add test
+- Model tests: `ModelTest-<model>` (e.g., `ModelTest-LeNet`)
+
+### Simulation Configuration
+
+Available configurations in `sims/verilator/`:
+
+- `BuckyballToyVerilatorConfig`: Single-core configuration for unit testing
+- `BuckyballGobanVerilatorConfig`: Multi-core configuration (1 tile, 4 cores) with shared accelerators
+- `BuckyballGoban2TileVerilatorConfig`: Multi-tile configuration (2 tiles, 8 cores) for SPMD workloads
+- Custom configs: Define in Scala configuration files
+
+**Multi-core Simulation:**
+
+For Goban-based configurations, workloads must implement SPMD patterns with hardware barrier synchronization:
+
+```bash
+# Run Goban multi-core test
+bbdev verilator --run \
+  '--binary barrier_test-baremetal \
+    --config sims.verilator.BuckyballGobanVerilatorConfig \
+    --batch'
+```
+
+See [Goban Multi-Core Architecture](Goban%20Multi-Core%20Architecture.md) for detailed multi-core programming guidance.
+
+## Code Organization
+
+### Directory Structure
+
+```
+buckyball/
+├── arch/                    # RTL design (Chisel/Scala)
+│   ├── src/main/scala/
+│   │   ├── examples/        # Reference designs
+│   │   ├── framework/       # Core framework
+│   │   └── sims/            # Simulation harness
+│   └── tests/               # RTL unit tests
+├── bb-tests/                # Software workloads and tests
+│   ├── workloads/src/       # Test applications
+│   │   ├── ModelTest/       # ML model inference tests
+│   │   ├── OpTest/          # Operation tests
+│   │   └── custom/          # User-defined workloads
+│   └── sardine/             # Test framework
+├── compiler/                # MLIR-based compiler
+├── frontend/                # Software framework
+├── backend/                 # System support libraries
+└── scripts/                 # Build and utility scripts
+```
+
+### Key Subsystems
+
+| Subsystem | Purpose |
+|-----------|---------|
+| `framework.balldomain` | Accelerator module (Ball) framework |
+| `framework.top.GlobalConfig` | System-wide configuration |
+| `sims.verilator` | Verilator simulation harness |
+| `bb-tests.sardine` | Test orchestration |
+| `bbAgent` | Software agent/orchestration |
+
+## Common Development Tasks
+
+### Modifying RTL
+
+1. Edit Chisel files in `arch/src/main/scala/`
+2. Rebuild simulations:
+   ```bash
+   cd arch
+   mill arch.test  # Run unit tests
+   ```
+3. Verify with Verilator simulation
+
+### Adding Custom Test Workload
+
+1. Create source files in `bb-tests/workloads/src/<category>/`
+2. Add CMakeLists.txt if needed
+3. Update test configuration in `sardine/` if using test framework
+4. Run with `bbdev verilator --run '--binary <workload-name> ...'`
+
+### Debugging Simulations
+
+**Enable waveform capture:**
+
+```bash
+bbdev verilator --run '--vcd out.vcd --binary <workload> --batch'
+```
+
+**Open waveforms:**
+
+```bash
+gtkwave out.vcd &
+```
+
+**Trace specific signals:**
+- Add `dontTouch` or `debug` annotations in Chisel
+- Verify signal names in generated RTL
+
+## Testing and Validation
+
+### Unit Tests
+
+RTL unit tests:
+
+```bash
+cd arch
+mill arch.test
+```
+
+### Integration Tests
+
+Full system tests using Verilator:
+
+```bash
+./scripts/nix/test-suite.sh  # Run full test suite (if available)
+```
+
+### Coverage-Driven Testing
+
+Enable coverage tracking (if supported):
+
+```bash
+bbdev verilator --run '--coverage --binary <test> --batch'
+```
+
+## Continuous Integration
+
+### Pre-commit Hooks
+
+Installed hooks validate:
+- Code formatting
+- Lint checks (Scala, C++)
+- CMake syntax
+
+```bash
+# Manual pre-commit check
+pre-commit run --all-files
+```
+
+### CI Workflows
+
+GitHub Actions workflows (`.github/workflows/`):
+- `test.yml`: Runs Verilator tests on push
+- `lint.yml`: Code quality checks
+- `build.yml`: Compiler and RTL builds
+
+## Troubleshooting
+
+### Build Issues
+
+| Problem | Solution |
+|---------|----------|
+| `nix develop` fails | Update flake: `nix flake update` |
+| Scala compilation errors | Ensure `mill` is up-to-date: `mill --version` |
+| Missing dependencies | Run `./scripts/nix/build-all.sh` again |
+
+### Simulation Issues
+
+| Problem | Solution |
+|---------|----------|
+| Test timeout | Reduce workload size or increase timeout |
+| Out-of-memory | Check workload data size, reduce test scale |
+| Incorrect results | Enable waveform capture for debugging |
+
+### Environment Issues
+
+```bash
+# Reset environment
+rm -rf .mill-cache
+nix flake update
+nix develop --impure
+```
+
+## Recent Changes
+
+- **bbdev updates**: Improved tool performance and added new simulation options
+- **Build system**: Enhanced CMake support for workload compilation
+- **Nix setup**: Added Yosys and OpenSTA for optional synthesis flows
+- **Test framework**: Updated sardine framework for new simulation semantics
+
+## See Also
+
+- [Verilator Simulation and CI](Verilator%20Simulation%20and%20CI.md)
+- [GemminiBall Architecture](GemminiBall%20Architecture.md)
+- [Buckyball ISA Documentation](../Overview/Buckyball%20ISA.md)