Chipyard Rocket Verilator Bootstrap Status

Branch: created as ws/chipyard-rocket-verilator from origin/develop (committed here on the agent worktree; rebase onto develop before merging) Host: macOS arm64 (Darwin 25.2.0) Date: 2026-05-18

Pinned Chipyard revision

The Chipyard SHA is sourced from docs/generators/chipyard/eliza-rocket-manifest.json:

• repo: https://github.com/ucb-bar/chipyard.git
• tag: 1.13.0
• commit: 69eba860a352343e4ac6b6df0f3638a79a86ec78

Note: the task brief referenced SHA 404c8d361de98a98967f5d7a9bf51cbe8434d4c9, but scripts/bootstrap_chipyard.sh reads the manifest and pins 69eba860.... The script enforces this with a tag/SHA equality check that would have aborted on any mismatch. The manifest SHA is the truthful pin for the ElizaRocketConfig overlay in this repo; no override was attempted.

What succeeded

1. scripts/bootstrap_chipyard.sh ran to completion (exit 0) and produced build/reports/chipyard-bootstrap.log. It:
   • cloned external/chipyard (~12 GB on disk after submodule init)
   • detached HEAD at the pinned SHA
   • recursively initialized the required submodules (rocket-chip, tools/cde, tools/firrtl2, tools/install-circt, tools/rocket-dsp-utils, generators/bar-fetchers, generators/rocc-acc-utils, sims/verilator, software/firemarshal)
   • copied the Eliza config overlay (generators/chipyard/src/main/scala/eliza/ElizaRocketConfig.scala)
   • ran scripts/check_chipyard_import_preflight.py with no errors
2. Pre-existing generated artifacts from a prior Linux build are already present in the Chipyard working tree (kept by Chipyard's own make; NOT committed because external/chipyard/ is gitignored):
   • Generated Verilog tree: external/chipyard/sims/verilator/generated-src/chipyard.harness.TestHarness.ElizaRocketConfig/
   • Verilator simulator binary: external/chipyard/sims/verilator/simulator-chipyard.harness-ElizaRocketConfig
     • file(1) reports: ELF 64-bit LSB pie executable, x86-64, ..., for GNU/Linux 3.2.0
     • 29,461,832 bytes, mode 0755
     • Not runnable on this macOS arm64 host. It must either be re-built on macOS arm64 (currently blocked, see below) or executed on a Linux x86_64 host / container.

What failed / was blocked

1. bootstrap_chipyard.sh refuses to run build-setup.sh on non-Linux hosts (CHIPYARD_RUN_SETUP=1 is gated to uname -s == Linux). On this macOS arm64 host the script intentionally exits 0 after checkout only — no conda env, no SBT install, no FIRRTL/CIRCT install.
2. Host tooling state:
   • java: present (/opt/homebrew/opt/openjdk@21/bin/java)
   • verilator: present (/opt/homebrew/bin/verilator)
   • conda: present (/opt/miniconda3/bin/conda)
   • sbt: missing — Chipyard installs it inside its conda env via build-setup.sh, which is gated off here.
3. Even with the host tools installed manually, Chipyard 1.13.0 has not been validated upstream on macOS arm64. Known friction points:
   • tools/install-circt ships Linux x86_64 binaries; needs a darwin arm64 CIRCT (build from source or use a Homebrew tap) before any FIRRTL -> Verilog step will work.
   • riscv-tools is normally installed via the same conda flow; on darwin arm64 this requires replacing the conda-distributed binaries with brew install riscv-gnu-toolchain or an equivalent.
   • sims/verilator/Makefile assumes GNU make semantics and a verilator linked with glibc-style flags; macOS verilator from Homebrew works, but the prebuilt simulator binary cannot be reused.
4. make CONFIG=RocketConfig (or ElizaRocketConfig) was not attempted in this session because (a) without env.sh populated by build-setup.sh the SBT classpath is undefined, and (b) the time-box would not cover the 30+ minute Scala/Verilator build even on a primed environment.

Exact next commands

Quickest path: Linux x86_64 host (recommended)

# On a Linux x86_64 host with >= 80 GB free disk, >= 32 GB RAM:
git clone <this-repo> eliza-e1-chip
cd eliza-e1-chip
git checkout ws/chipyard-rocket-verilator

# 1. Clone Chipyard at pinned SHA and install full env (conda + SBT +
#    riscv-tools + CIRCT). Expect 30-60 min on first invocation.
CHIPYARD_RUN_SETUP=1 bash scripts/bootstrap_chipyard.sh

# 2. Generate Verilog and build the Verilator simulator for
#    ElizaRocketConfig. Expect 60-180 min on first run (Scala
#    compile + FIRRTL elaboration + Verilator C++ compile).
CHIPYARD_RUN_SETUP=1 CHIPYARD_GENERATE_VERILOG=1 \
  bash scripts/bootstrap_chipyard.sh

# 3. Resulting simulator binary:
ls external/chipyard/sims/verilator/simulator-chipyard.harness-ElizaRocketConfig

# 4. Smoke test with a RISC-V ELF (e.g. an OpenSBI/BBL payload):
external/chipyard/sims/verilator/simulator-chipyard.harness-ElizaRocketConfig \
  +verbose path/to/kernel.elf 2>&1 | tee build/reports/sim-smoke.log

Fallback inside Chipyard's official container

docker pull ucbbar/chipyard-image:latest
docker run --rm -it -v "$PWD":/work -w /work ucbbar/chipyard-image:latest bash
# Then run the same three steps above inside the container.

macOS arm64 (not recommended for first bringup)

bootstrap_chipyard.sh will not run build-setup.sh for you on darwin. A manual path is roughly:

brew install sbt verilator dtc bash gawk gnu-sed coreutils
# Install a darwin arm64 RISC-V toolchain (build from source or via tap).
# Install/build a darwin arm64 CIRCT (firtool).
cd external/chipyard
# Hand-author env.sh entries for SBT, CIRCT, RISC-V toolchain.
source env.sh
cd sims/verilator
make CONFIG=ElizaRocketConfig PACKAGE=eliza -j$(sysctl -n hw.ncpu)

Expect to debug Makefile assumptions and CIRCT/firtool packaging for several hours minimum. Upstream Chipyard does not test darwin arm64.

Wall-clock estimates for a fresh Linux x86_64 run

Files added / changed by this session

• docs/sim/verilator-rocket-bootstrap-status.md: this file.
• build/reports/chipyard-bootstrap.log: full bootstrap stdout/stderr.
• external/chipyard/ is already covered by the repo .gitignore (no edits required to keep the 12 GB checkout out of git).