[codex] misc: Fix Python runtime detection

[jensen-yan]

Motivation

Some builds can fail during SCons configure with Checking Python version... no even after Python.h is found. This is not necessarily a Python version problem: the configure probe links an embedded Python test and then runs it, so non-system Python installations such as conda also need their libpython directory to be visible to the runtime loader.

The README and quick-start docs also still recommended installing a Python 3.8 conda environment for high Python versions, which is misleading now that Ubuntu 24.04's default Python 3.12 works.

Approach

• Parse python*-config output with shlex.split().
• Reuse absolute -L paths from python*-config as runtime library paths for embedded Python configure probes and resulting binaries.
• Remove the old Python 3.8/miniconda guidance from README and quick start.
• Update the documented recommended environment to Ubuntu 24.04 with system Python 3.12.

Validation

• python3 -m py_compile SConstruct
• Forced SCons configure reached and passed Checking Python version... 3.12.3; the bounded build command later timed out during generated-header work, not during Python detection.
• The generated Python configure probe includes RUNPATH entries derived from python3-config -L paths and runs successfully, printing 3.12.3.

Summary by CodeRabbit

• Documentation

  • Updated build/setup instructions to target Ubuntu 24.04 and recommend the default system Python 3.12
  • Improved troubleshooting guidance for configuration-stage errors with clearer diagnostics
  • Removed legacy alternative Python-version setup instructions for a simpler environment

• Improvements

  • Better handling of embedded-Python library locations so runtime dependencies are found more reliably

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

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📥 Commits

Reviewing files that changed from the base of the PR and between 3c85ed2 and 39fdfc2.

📒 Files selected for processing (3)

• README.md
• SConstruct
• docs/quick_start.md

✅ Files skipped from review due to trivial changes (2)

• docs/quick_start.md
• README.md

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📝 Walkthrough

Walkthrough

This PR standardizes build/docs on Ubuntu 24.04 with system Python 3.12, updates SConstruct to parse embedded-Python flags with shlex and add absolute -L paths to RPATH, and refactors FAQ troubleshooting to point users to scons_config.log for configure-stage errors.

Changes

Ubuntu 24.04 and Python 3.12 Standardization

Layer / File(s)	Summary
Embedded Python library path configuration SConstruct	Adds shlex import and updates flag_filter helper to robustly parse embedded-Python flags using shlex.split, extracts absolute -L library paths, and propagates them to build RPATH and runtime LD_LIBRARY_PATH to ensure non-system libpython discoveries.
Build environment setup documentation README.md, docs/quick_start.md	Both files update dependency setup guidance from Ubuntu 22.04 to Ubuntu 24.04, document that system Python 3.12 works without miniconda or version downgrade, remove legacy Python environment setup sections, and clarify Docker usage preference.
FAQ and diagnostic troubleshooting guidance README.md, docs/quick_start.md	FAQ "Python not found" entries now direct users to inspect build/RISCV/gem5.build/scons_config.log for configure-stage errors, clarify GCC vs clang warning flag issues, and remove outdated Python environment troubleshooting steps in favor of build log inspection.

🎯 2 (Simple) | ⏱️ ~12 minutes

A rabbit hops through build logs with glee,
Ubuntu twenty-four-oh-four, Python three-twelve, all working free!
No miniconda, no downgrade pains—just system tools at hand,
Library paths now travel right through RPATH-land. 🐰✨

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 inconclusive)

Check name	Status	Explanation	Resolution
Title check	❓ Inconclusive	The title 'Fix Python runtime detection' partially addresses the main technical change (RPATH derivation from python-config), but obscures it with a generic '[codex] misc:' prefix and does not clearly convey the primary objective of updating documentation to recommend Ubuntu 24.04 with Python 3.12.	Consider using a more specific title like 'Update Python environment docs to Ubuntu 24.04 and fix embedded Python runtime detection' to clarify the main changes.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix-python

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[coderabbitai]

Actionable comments posted: 2

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@docs/quick_start.md`:
- Line 170: Replace the ambiguous phrase "参考关于在 Docker 中运行的 README" in
docs/quick_start.md (the sentence at Line 170) with a direct Markdown link to
the repository's Docker README so readers can jump directly; update the text to
something like "参考关于在 Docker 中运行的 README（链接）" where the link points to the
project’s Docker README file, ensuring the markdown uses a relative path and the
link text clearly says "Docker README".

In `@README.md`:
- Around line 443-448: Replace the typo "apply this path" with "apply this
patch" in the README where the remediation instruction appears (the sentence
that precedes the command `git apply ext/xs_env/clang-warning-suppress.patch`
and currently reads "apply this path") so the wording matches the command and
removes confusion.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

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Configuration used: defaults

Review profile: CHILL

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Run ID: 68428504-fbce-42f9-98f3-d441f26b42a5

📥 Commits

Reviewing files that changed from the base of the PR and between 7cc32ed and 3c85ed2.

📒 Files selected for processing (3)

• README.md
• SConstruct
• docs/quick_start.md

[chatgpt-codex-connector]

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[jensen-yan]

Addressed in 39fdfc2efa: removed the global ENV['LD_LIBRARY_PATH'] mutation and now rely on the RPATH derived from python*-config -L paths. This keeps the runtime path scoped to the linked Python probe/binary and avoids contaminating later SCons child processes.

[github-actions]

🚀 Coremark Smoke Test Results

Branch	IPC	Change
Base (xs-dev)	2.3130	-
This PR	2.3130	➡️ 0.0000 (0.00%)

✅ Difftest smoke test passed!

[github-actions]

🚀 Coremark Smoke Test Results

Branch	IPC	Change
Base (xs-dev)	2.3130	-
This PR	2.3130	➡️ 0.0000 (0.00%)

✅ Difftest smoke test passed!