Skip to content

codex.md

Latest commit

 

History

History
34 lines (24 loc) · 1.49 KB

codex.md

File metadata and controls

34 lines (24 loc) · 1.49 KB
Raw

Codex Notes

This repo has a persistent on-disk preset layout. Treat changes in kernel/include/preset.h and tools/preset.h as ABI changes, not normal refactors.

Rules

  • Do not change MAP_SYMBOL_NUM casually.
  • map_symbol_t sits before header_backup inside setup_preset_t, so changing MAP_SYMBOL_NUM moves header_backup and every field after it.
  • That offset drift is what broke upgrade parsing across 0.13.1, 0.13.2, and newer builds.
  • tools/preset.h is the tools-side mirror of kernel/include/preset.h; keep them in sync when layout changes.

Known Header Backup Offsets

  • Official upstream 0.13.0 / 0.13.1: current_header_backup_offset - 16
  • Official upstream 0.13.2 and current main: current_header_backup_offset
  • current_header_backup_offset - 8 is kept only as a fallback for non-official intermediate/local images

tools/patch.c resolves this through preset_header_backup() and validates candidates with the saved primary-entry header.

Safe Future Changes

  • Prefer fixed-capacity storage for persistent structs.
  • Prefer using reserved space like __[] for small new metadata.
  • If a serialized struct must change, add explicit versioned parsing instead of relying on current offsetof(...).

Validation

  • Rebuild tools with wsl -d Ubuntu bash -lc "cd /mnt/e/Project/self/KernelPatch/tools && make".
  • Re-test upgrade flow with:
    • old patched boot -> unpack
    • repatch extracted kernel
    • repack boot
    • unpack repacked boot
    • repatch again