Docker file issue about AVX-512 & Questions regarding Bazel

[jesse486]

I'm writing to summarize the environment setup challenges I encountered while building OpenROAD-flow-scripts (ORFS) locally, and
to ask about the current status of Bazel-based builds.

Environment

• OS: Ubuntu 22.04.4 LTS
• CPU: Intel Core i9-14900K (12th gen+ hybrid architecture with P-cores and E-cores)

1. Docker Image Failure — Illegal Instruction (AVX-512)

The pre-built Docker image (openroad/orfs) crashes at the CTS stage with:

Error: cts.tcl, 86 child killed: illegal instruction

Root cause: The Docker image binaries are compiled with AVX-512 instructions, but the i9-14900K has AVX-512 disabled by default due to its hybrid architecture (E-cores don't support AVX-512, so Intel fuses it off to allow thread migration between P-cores and E-cores). Since Docker runs binaries directly on the host CPU without instruction translation, any AVX-512 instruction causes a SIGILL.
Note: There is no alternative Docker image compiled without AVX-512 on Docker Hub.

2. SWIG / Tcl Version Incompatibility

The OpenROAD dependency installer installs SWIG 4.3.0, which is required to avoid linker errors (multiple definition of SwigString_FromString etc. with SWIG 4.0.2). However, SWIG 4.3.0 generates code using Tcl_Size, a type introduced in Tcl 9.x, while the system provides Tcl 8.6. This results in compilation errors across ~50 SWIG interface (.i) files:

error: 'Tcl_Size' was not declared in this scope

Some .i files (e.g., StaTclTypes.i, tclCmdInputWidget.h) already have compatibility typedefs, but the majority do not.
Fix: Added the following compatibility block to the %{ %} section of all affected .i files:

  #include <tcl.h>
  #if TCL_MAJOR_VERSION < 9 && !defined(Tcl_Size)
  typedef int Tcl_Size;
  #endif

This required patching approximately 50 files under tools/OpenROAD/src/. With this fix and SWIG 4.3.0, the build completes successfully.

Current Status

After all the above fixes, the full RTL-to-GDS flow runs successfully on the default gcd design with nangate45:

• Synthesis, Floorplan, Placement, CTS, Routing, Finishing, and GDS merge all complete without errors.
• OpenROAD version: 26Q1-2747-gb3a329795b
• Yosys version: 0.63

Questions regarding Bazel

I noticed that the README recommends Bazel as an option for building ORFS, while the BuildLocally.md documentation marks it as
"unsupported, for ORFS/OpenROAD developers".
Could you clarify:

1. What is the current maturity level of the Bazel-based build? Is it ready for general use?
2. Does Bazel handle the SWIG/Tcl compatibility issue automatically?
3. Are all designs and flow stages available through Bazel, or only a subset?

Bazel's hermetic build approach would be ideal for avoiding the dependency issues described above, so I'd like to understand whether it's a viable path forward.

Regarding a Dockerfile for non-AVX-512 environments

Since the official Docker image assumes AVX-512 support, which is unavailable on Intel 12th gen+ consumer CPUs, would it be helpful if I contributed a Dockerfile that builds from source without AVX-512 dependency? I can provide one based on my current working local build environment, which could serve as a reference for others with similar hardware. Please let me know if this would be a welcome contribution to the project.

[maliberty]

@vvbandeira please advise on the docker image
@hzeller please comment on the tcl issue

[hzeller]

The bazel build builds with tcl 8.6.16 currently (which already has the Tcl_Size change; about to switch to tcl 9 so that we can pack related files in a zipfs) and uses swig 4.3 (I also made an effort to make things compile with older than 8.6.13 versions of Tcl).
So yes, bazel comes with all batteries included to successfully compile tcl and won't rely on any local tcl version.

[jesse486]

That's really helpful to know — thank you for clarifying. Good to hear that the Bazel build is fully self-contained with its own Tcl 8.6.16 and SWIG 4.3.