Wiki: Create Spoke Page for Core - Object-Layout

[LSantha]

Goal

Document the internal representation of Java objects in memory (Object Layout) within JNode.

Agent Execution Checklist

• 1. Research: Analyze core/src/core/org/jnode/vm/classmgr/ObjectLayout.java. Understand the role of the TIB (Type Information Block) slot, Flags slot, and object alignment. Check how headers are structured in both 32-bit and 64-bit modes.
• 2. Create Spoke Page: Create .wiki/Object-Layout.md following the Hub/Spoke model in WIKI_SCHEMA.md (200-500 lines).
  • Include a diagram (Mermaid or ASCII) showing the memory layout of an object.
  • Explain the TIB, Flags, and where instance fields begin.
• 3. Link from Hub: Add a link to [[Object-Layout]] in the relevant section of .wiki/Architecture.md.
• 4. Update Index: Add a new row to all four tables in .wiki/index.md and maintain alphabetical order.
• 5. COMMIT & PUSH (CRITICAL): You MUST manually run git push inside the .wiki directory.

  WARNING: The OpenCode Action infrastructure WILL NOT auto-push changes in the .wiki folder. If you do not run git push explicitly, your work will be permanently lost when the runner shuts down.

• 6. VERIFY: Run git ls-remote origin master after pushing to verify the commit reached the remote repository.
• 7. REPORT: Comment on this issue with the direct URL to the new wiki page (e.g., https://github.com/LSantha/jnode_ai/wiki/Object-Layout) to allow immediate verification.

[LSantha]

/oc fix this

[LSantha]

/oc fix this

[opencode-agent]

Done! I've completed all the required tasks:

1. Research: Analyzed ObjectLayout.java and TIBLayout.java to understand header structure (TIB at slot -1, Flags at slot -2), header size (2 slots = 8/16 bytes in 32/64-bit), and object alignment (8 bytes)

2. Created Spoke Page: Created .wiki/Object-Layout.md with:

   • Mermaid/ASCII diagram showing object memory layout
   • Explanation of TIB, Flags, and instance field layout
   • 32-bit vs 64-bit differences
   • TIB array contents from TIBLayout
   • Alignment rules

3. Linked from Hub: Added link in .wiki/Architecture.md (Related Pages section)

4. Updated Index: Added to all four tables in .wiki/index.md:

   • Pages table: Object-Layout entry
   • Concepts → Pages: TIB concept
   • Source Path → Pages: classmgr/ → Object-Layout
   • Task Routing: Added Object-Layout to "Debugging memory issues"

5. Committed & Pushed: Successfully pushed to the wiki repository

6. Verified: git ls-remote origin master shows commit 8e508eb

7. Reported: Commented on issue with wiki URL: https://github.com/LSantha/jnode_ai/wiki/Object-Layout

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